Things Visible in Two Classes

> I'm trying to call a method from

> "AnalysisCalc.class" using variables visible to both

> classes.

but in your code example the variables are not visible to each class

You need to learn about object references. Please see the java tutorials (link in left column). For AnalysisCalc to modify an instance variable of Analysis it would need a REFERENCE to an instance of Analysis.

> The intent of the program is to decrement a

> variable using a while loop.

Why not just assign the value after you're done counting down?

> The intent of using

> "AnalysisCalc.class" is to manage my code better

> rather than consolidate all the code in

> "Analysis.class".

In your example, I'd say there's no point in splitting the code into 2 classes. In fact, it violates encapsulation - why is AnalysisCalc modifying internal state of another class? Why not have analysis calc hold onto the values and have Analysis look at them when appropriate (if ever).

> How do I modify the following source

> code for these classes?

>

(Again, see my comments above about analysis calc 'owning' the data its modifying)

Pass a reference to AnalysisCalc like:

public class AnalysisCalc {

private Analysis analysis;

// AnalysisCalc constructor

public AnalysisCalc(Analysis analysis)

{

this.analysis = analysis;

rundata( );

}

public void rundata( )

{

if( analysis.variableA == true)

{

analysis.variableX = 100;

analysis.variableA = false;

}

analysis.variableX--;

}

}

> (NOTE: Don't worry about other aspects of program such

> as I/O since I know how to handle that )

I'm not worried; but I don't really believe you either... :\

larsonaa at 2007-7-15 2:30:22 >

OK, forget the code I posted previously.

The following code in files Trajectory.java and Calculate.java have a similar problem. I'm trying to get my method set up simple with a decrement logic because later the logic for the method will become more complex. I want to keep all this complex code out of the Trajectory.java file and manage it from the Calculate.java file. I would set up package and import design, but my ISP will not accept package design in building website since fully qualified names must be used to avoid naming conflicts.

key code segments in file trajectory.java, being analogous to Analysis.java, include>

Calculate Z = new Calculate();

while(sentinel){

Z.rundata();

if( altitude < 10 )

sentinel = false;

}

The file analogous to AnalysisCalc.java is Calculate.java

// Trajectory Analysis Program: Trajectory.java

import java.awt.*;

import java.awt.event.*;

import javax.swing.*;

public class Trajectory extends JApplet implements ActionListener {

final double MAX = 90.0;

final double MIN = -90.0;

final double MAX_ALTITUDE = 2000000.0;

final double MIN_ALTITUDE = 0.0;

private JTextArea introductionArea, resultsArea;

private JLabel spanLabel, chordLabel,

thicknessLabel, massLabel, altitudeLabel, velocityLabel,

trajectory_angleLabel, time_incrementLabel, rotation_factorLabel,

calculationLabel, resultsLabel;

private JTextField spanField, chordField, thicknessField,

massField, altitudeField, velocityField, trajectory_angleField,

time_incrementField, rotation_factorField;

private JButton startButton, resetButton, contButton, abortButton;

String introduction_string, span_string, chord_string, thickness_string, mass_string,

altitude_string, velocity_string, trajectory_angle_string,

time_increment_string, rotation_factor_string, results_string;

public double span, chord, thickness, mass, altitude, velocity, trajectory_angle, time_increment,

rotation_factor, distance, velocity_fps, elapsed_time;

boolean value, sentinel;

// create objects

public void init()

{

Calculate Z = new Calculate();

span = 0;

chord = 0;

thickness = 0;

mass = 0;

altitude = 0;

velocity = 0;

trajectory_angle = 0;

time_increment = 0;

rotation_factor = 0;

distance = 0;

velocity_fps = 0;

elapsed_time = 0;

velocity_fps = 0;

elapsed_time = 0;

value = true;

sentinel = true;

introduction_string =

"DEBRIS TRAJECTORY PROGRAM\n"

+ "designed by Weldon K. Chafin, Jr.\n\n"

+ "Inspired by the brave heroes of the Columbia Accident "

+ "of February 1, 2003.\n\n"

+ "This program determines trajectory for an object modeled "

+ "as a rectangular prism having given mass falling through "

+ "the atmosphere. The object is assumed to oscillate with same "

+ "frequency about all six possible permutations for axis "

+ "angular velocity vectors as the means to simulate "

+ "equally likely random events.\n\n"

+ "NOTE: This program is still under construction. "

+ "I predict this program will be fully functional by October 4, 2003. "

+ "Then it should have calculation capability comparable to the C++ program version I created "

+ "for the Columbia Accident Investigation Board (CAIB) to predict locations of Columbia debris. "

+ "In fact, the CAIB forwarded my program as an analytical tool to NASA "

+ "JSE Early Sightings Assessment Team tasked with finding high interest "

+ "Columbia debris items via radar imaging.";

span_string = "";

chord_string = "";

thickness_string = "";

mass_string = "";

altitude_string = "";

velocity_string = "";

trajectory_angle_string = "";

time_increment_string = "";

rotation_factor_string = "";

results_string = "";

// create container & panel

Container container = getContentPane();

Panel panel = new Panel( new FlowLayout( FlowLayout.LEFT));

container.add( panel );

// set up vertical boxlayout

Box box = Box.createVerticalBox();

Box inputbox1 = Box.createHorizontalBox();

Box inputbox2 = Box.createHorizontalBox();

Box inputbox2a = Box.createHorizontalBox();

Box inputbox2b = Box.createHorizontalBox();

Box inputbox2c = Box.createHorizontalBox();

Box inputbox2d = Box.createHorizontalBox();

Box inputbox3 = Box.createHorizontalBox();

Box buttonbox = Box.createHorizontalBox();

// set up introduction

introductionArea = new JTextArea( introduction_string, 10, 50 );

introductionArea.setEditable( false );

box.add( new JScrollPane( introductionArea ) );

box.add( Box.createVerticalStrut (10) );

box.add( inputbox1);

box.add(inputbox2a);

Dimension minSize = new Dimension(5, 15);

Dimension prefSize = new Dimension(5, 15);

Dimension maxSize = new Dimension(Short.MAX_VALUE, 15);

inputbox2a.add(new Box.Filler(minSize, prefSize, maxSize));

// set up span

spanLabel = new JLabel( "span (feet)" );

spanField = new JTextField(5 );

inputbox2a.add( spanLabel );

inputbox2a.add( spanField );

inputbox2a.add(new Box.Filler(minSize, prefSize, maxSize));

// set up chord

chordLabel = new JLabel( "chord (feet)" );

chordField = new JTextField(5 );

inputbox2a.add( chordLabel );

inputbox2a.add( chordField );

inputbox2a.add(new Box.Filler(minSize, prefSize, maxSize));

// set up thickness

thicknessLabel = new JLabel( "thickness (feet)" );

thicknessField = new JTextField(5 );

inputbox2a.add( thicknessLabel );

inputbox2a.add( thicknessField );

inputbox2a.add(new Box.Filler(minSize, prefSize, maxSize));

box.add( Box.createVerticalStrut (10) );

box.add(inputbox2b);

inputbox2b.add(new Box.Filler(minSize, prefSize, maxSize));

// set up mass

massLabel = new JLabel( "mass (slugs)" );

massField = new JTextField(5);

inputbox2b.add( massLabel );

inputbox2b.add( massField );

inputbox2b.add(new Box.Filler(minSize, prefSize, maxSize));

// set up altitude

altitudeLabel = new JLabel( "altitude (feet)");

altitudeField = new JTextField(5 );

inputbox2b.add( altitudeLabel );

inputbox2b.add( altitudeField );

inputbox2b.add(new Box.Filler(minSize, prefSize, maxSize));

// set up velocity

velocityLabel = new JLabel( "velocity (Mach Number)");

velocityField = new JTextField(5);

inputbox2b.add( velocityLabel );

inputbox2b.add( velocityField );

inputbox2b.add(new Box.Filler(minSize, prefSize, maxSize));

box.add( Box.createVerticalStrut (10) );

Dimension minSize2c = new Dimension(160, 15);

Dimension prefSize2c = new Dimension(160, 15);

Dimension maxSize2c = new Dimension(Short.MAX_VALUE, 15);

box.add(inputbox2c);

inputbox2c.add(new Box.Filler(minSize2c, prefSize2c, maxSize2c));

// set up trajectory_angle

trajectory_angleLabel = new JLabel( "trajectory angle (degrees)");

trajectory_angleField = new JTextField(5);

inputbox2c.add( trajectory_angleLabel );

inputbox2c.add( trajectory_angleField );

inputbox2c.add(new Box.Filler(minSize2c, prefSize2c, maxSize2c));

box.add( Box.createVerticalStrut (10) );

Dimension minSize2d = new Dimension(50, 15);

Dimension prefSize2d = new Dimension(50, 15);

Dimension maxSize2d = new Dimension(Short.MAX_VALUE, 15);

box.add(inputbox2d);

inputbox2d.add(new Box.Filler(minSize2d, prefSize2d, maxSize2d));

// set up time_increment

time_incrementLabel = new JLabel( "time increment (seconds)" );

time_incrementField = new JTextField(5);

inputbox2d.add( time_incrementLabel );

inputbox2d.add( time_incrementField );

inputbox2d.add(new Box.Filler(minSize2d, prefSize2d, maxSize2d));

// set up rotation_factor

rotation_factorLabel = new JLabel( "rotation factor (number)" );

rotation_factorField = new JTextField(5);

inputbox2d.add( rotation_factorLabel );

inputbox2d.add( rotation_factorField );

inputbox2d.add(new Box.Filler(minSize2d, prefSize2d, maxSize2d));

box.add( Box.createVerticalStrut (10) );

box.add( buttonbox);

Dimension minSizeB = new Dimension(10, 30);

Dimension prefSizeB = new Dimension(10, 30);

Dimension maxSizeB = new Dimension(Short.MAX_VALUE, 30);

buttonbox.add(new Box.Filler(minSizeB, prefSizeB, maxSizeB));

// set up start

startButton = new JButton( "START" );

buttonbox.add( startButton );

buttonbox.add(new Box.Filler(minSizeB, prefSizeB, maxSizeB));

// set up reset

resetButton = new JButton( "RESET" );

buttonbox.add( resetButton );

buttonbox.add(new Box.Filler(minSizeB, prefSizeB, maxSizeB));

// set up cont

contButton = new JButton( "CONTINUE" );

buttonbox.add( contButton );

buttonbox.add(new Box.Filler(minSizeB, prefSizeB, maxSizeB));

// set up abort

abortButton = new JButton( "ABORT" );

buttonbox.add( abortButton );

buttonbox.add(new Box.Filler(minSizeB, prefSizeB, maxSizeB));

box.add( Box.createVerticalStrut (10) );

// set up results

resultsArea = new JTextArea( results_string, 6, 50 );

resultsArea.setEditable( false );

box.add( new JScrollPane( resultsArea ) );

// add box to panel

panel.add( box );

// register event handlers

spanField.addActionListener( this );

chordField.addActionListener( this );

thicknessField.addActionListener( this );

massField.addActionListener( this );

altitudeField.addActionListener( this );

velocityField.addActionListener( this );

trajectory_angleField.addActionListener( this );

time_incrementField.addActionListener( this );

rotation_factorField.addActionListener( this );

startButton.addActionListener( this );

resetButton.addActionListener( this );

contButton.addActionListener( this );

abortButton.addActionListener( this );

reset();

} // end method init

public void t_r_a_test (double trajectory_angle) throws Tare {

if (trajectory_angle > MAX || trajectory_angle < MIN)

throw new Tare("\ntrajectory_angle "

+ trajectory_angle + " is outside of allowable range\n\n"

+ "Try another value for the trajectory angle\n"

+ "( " + MIN + " <= trajectory angle <= " + MAX + " )" );

} // end method t_r_a_test

public void a_r_e_test (double altitude) throws Are {

if ( altitude > MAX_ALTITUDE )

throw new Are("\naltitude "

+ altitude + " is outside of allowable range\n\n"

+ "Try value for altitude\n"

+ "( " + MIN_ALTITUDE + " <= altitude <= "

+ MAX_ALTITUDE + " )" );

} // end method a_r_e_test

public void n_v_test (boolean value) throws Nve {

if ( value == false ){

if( span < 0 ){

span = 0;

throw new Nve("\nValue for "

+ " span must not be negative\n\n"

+ "Try another value ");

}

if( chord < 0 ){

chord = 0;

throw new Nve("\nValue for "

+ " chord must not be negative\n\n"

+ "Try another value ");

}

if( thickness < 0 ){

thickness = 0;

throw new Nve("\nValue for "

+ " thickness must not be negative\n\n"

+ "Try another value ");

}

if( mass < 0 ){

mass = 0;

throw new Nve("\nValue for "

+ " mass must not be negative\n\n"

+ "Try another value ");

}

if( altitude < 0 ){

altitude = 0;

throw new Nve("\nValue for "

+ " altitude must not be negative\n\n"

+ "Try another value ");

}

if( velocity < 0 ){

velocity = 0;

throw new Nve("\nValue for "

+ " velocity must not be negative\n\n"

+ "Try another value ");

}

if( time_increment < 0 ){

time_increment = 0;

throw new Nve("\nValue for "

+ " time increment must not be negative\n\n"

+ "Try another value ");

}

if( rotation_factor < 0 ){

rotation_factor = 0;

throw new Nve("\nValue for "

+ " rotation factor must not be negative\n\n"

+ "Try another value ");

}

} //end if( value == false )

} // end method n_v_test

// process events

public void actionPerformed( ActionEvent event )

{

// process spanField

if( event.getSource() == spanField ) {

span_string = spanField.getText();

span = Double.parseDouble( span_string);

}

// process chordField

if( event.getSource() == chordField ) {

chord_string = chordField.getText();

chord = Double.parseDouble( chord_string);

}

// process thicknessField

if( event.getSource() == thicknessField ) {

thickness_string = thicknessField.getText();

thickness = Double.parseDouble( thickness_string);

}

// process massField

if( event.getSource() == massField ) {

mass_string = massField.getText();

mass = Double.parseDouble( mass_string);

}

// process altitudeField

if( event.getSource() == altitudeField ){

altitude_string = altitudeField.getText();

altitude = Double.parseDouble( altitude_string);

}

// process velocityField

if( event.getSource() == velocityField ){

velocity_string = velocityField.getText();

velocity = Double.parseDouble( velocity_string);

}

// process trajectory_angleField

if( event.getSource() == trajectory_angleField ){

trajectory_angle_string = trajectory_angleField.getText();

trajectory_angle = Double.parseDouble( trajectory_angle_string);

}

// process time_incrementField

if( event.getSource() == time_incrementField ){

time_increment_string = time_incrementField.getText();

time_increment = Double.parseDouble( time_increment_string);

}

// process rotation_factorField

if( event.getSource() == rotation_factorField ){

rotation_factor_string = rotation_factorField.getText();

rotation_factor = Double.parseDouble( rotation_factor_string);

}

// process startButton event

if ( event.getSource() == startButton )

strtb();

// process resetButton event

if ( event.getSource() == resetButton )

reset();

// process contButton event

if ( event.getSource() == contButton )

cont();

// process abortButton event

if ( event.getSource() == abortButton )

abort();

} // end method actionPerformed

public void strtb()

{

try{

span = Double.parseDouble( spanField.getText() );

chord = Double.parseDouble( chordField.getText() );

thickness = Double.parseDouble( thicknessField.getText() );

mass = Double.parseDouble( massField.getText() );

altitude = Double.parseDouble( altitudeField.getText());

velocity = Double.parseDouble( velocityField.getText());

trajectory_angle = Double.parseDouble( trajectory_angleField.getText());

time_increment = Double.parseDouble( time_incrementField.getText() );

rotation_factor = Double.parseDouble( rotation_factorField.getText() );

if( span < 0 || chord < 0 || thickness < 0 || mass < 0

|| altitude < 0 || velocity < 0

|| time_increment < 0 || rotation_factor < 0 )

value = false;

t_r_a_test( trajectory_angle );

n_v_test( value );

a_r_e_test( altitude );

while(sentinel){

Z.rundata();

if( altitude < 10 )

sentinel = false;

}

results();

resultsArea.setText( results() );

}//end try

// process improperly formatted input

catch ( NumberFormatException numberFormatException ) {

JOptionPane.showMessageDialog( this,

"You must enter numbers in decimal format or integers",

"Invalid Number Format" ,

JOptionPane.ERROR_MESSAGE );

} // end catch NumberFormatException

catch ( ArithmeticException arithmeticException ) {

JOptionPane.showMessageDialog( this,

arithmeticException.toString(), "Arithmetic Exception" ,

JOptionPane.ERROR_MESSAGE );

} // end catch ArithmeticException

catch ( Tare tare ) {

JOptionPane.showMessageDialog( this,

tare.toString(), "-90 <= range <= 90 " ,

JOptionPane.ERROR_MESSAGE );

} // end catch Tare

catch ( Nve nve ) {

JOptionPane.showMessageDialog( this,

nve.toString(), " value less than zero" ,

JOptionPane.ERROR_MESSAGE );

} // end catch Nve

catch ( Are are ) {

JOptionPane.showMessageDialog( this,

are.toString(), " value greater than maximum" ,

JOptionPane.ERROR_MESSAGE );

} // end catch Are

} // end method strtb

public void reset()

{

span_string = "";

chord_string = "";

thickness_string = "";

mass_string = "";

altitude_string = "";

velocity_string = "";

trajectory_angle_string = "";

time_increment_string = "";

rotation_factor_string = "";

results_string = "";

spanField.setText( span_string );

chordField.setText( chord_string );

thicknessField.setText( thickness_string );

massField.setText( mass_string );

altitudeField.setText( altitude_string );

velocityField.setText( velocity_string );

trajectory_angleField.setText( trajectory_angle_string );

time_incrementField.setText( time_increment_string );

rotation_factorField.setText( rotation_factor_string );

resultsArea.setEditable( true );

resultsArea.setText( results_string );

resultsArea.setEditable( false );

span = 0;

chord = 0;

thickness = 0;

mass = 0;

altitude = 0;

velocity = 0;

trajectory_angle = 0;

time_increment = 0;

rotation_factor = 0;

distance = 0;

velocity_fps = 0;

elapsed_time = 0;

value = true;

}// end method reset

public void cont()

{

//later

}

public void abort()

{

//later

}

public String results()

{

results_string =

"Distance =\t\t" + distance + " miles\n"

+ "Altitude =\t\t" + altitude + " feet\n"

+ "Trajectory Angle =\t" + trajectory_angle + " degrees\n"

+ "Velocity =\t\t" + velocity_fps + " feet per second\n"

+ "Elapsed Time =\t\t" + elapsed_time + " seconds\n";

return results_string;

}

} //end class Trajectory

[code]

// Trajectory Analysis Program: Calculate.java

public class Calculate {

Trajectory T = new Trajectory();

// Calculate constructor

public Calculate()

{

rundata( );

}

public void rundata( )

{

T.altitude--;

}

} // end class Calculate

[/code]

analysis_gurua at 2007-7-15 2:30:22 >

eriklindquist:

I tried your suggestion, but it doesn't work.

This is what I did in trajectory.java:

"Calculate Z = new Calculate();" was retained in the init method definition as before.

The while statement in strtb method definition was changed to:

while(sentinel){

Z.rundata(this);

if( altitude < 10 )

sentinel = false;

}

The following is Calculate.java file:

// Trajectory Analysis Program: Calculate.java

public class Calculate {

// Calculate constructor

public Calculate()

{

rundata( );

}

public void rundata( Trajectory T)

{

T.altitude--;

}

} // end class Calculate

These are the compile errors

C:\JAVATEMP>calculate.java

C:\JAVATEMP>javac trajectory.java

trajectory.java:12: class Trajectory is public, should be declared in a file na

ed Trajectory.java

public class Trajectory extends JApplet implements ActionListener {

^

trajectory.java:49: cannot resolve symbol

symbol : class Calculate

location: class Trajectory

Calculate Z = new Calculate();

^

trajectory.java:49: cannot resolve symbol

symbol : class Calculate

location: class Trajectory

Calculate Z = new Calculate();

^

trajectory.java:539: cannot resolve symbol

symbol : variable Z

location: class Trajectory

Z.rundata(this);

^

4 errors

C:\JAVATEMP>javac calculate.java

calculate.java:3: class Calculate is public, should be declared in a file named

Calculate.java

public class Calculate {

^

calculate.java:14: cannot resolve symbol

symbol : class Trajectory

location: class Calculate

public void rundata( Trajectory T)

^

calculate.java:10: rundata(Trajectory) in Calculate cannot be applied to ()

rundata( );

^

3 errors

analysis_gurua at 2007-7-15 2:30:22 >

OK, corrected file name... the new compile error messages are as follows:

C:\JAVATEMP>javac Trajectory.java

Trajectory.java:49: cannot resolve symbol

symbol : class Calculate

location: class Trajectory

Calculate Z = new Calculate();

^

Trajectory.java:49: cannot resolve symbol

symbol : class Calculate

location: class Trajectory

Calculate Z = new Calculate();

^

Trajectory.java:539: cannot resolve symbol

symbol : variable Z

location: class Trajectory

Z.rundata(this);

^

3 errors

C:\JAVATEMP>javac Calculate.java

Calculate.java:14: cannot resolve symbol

symbol : class Trajectory

location: class Calculate

public void rundata( Trajectory T)

^

Calculate.java:10: rundata(Trajectory) in Calculate cannot be applied to ()

rundata( );

^

2 errors

analysis_gurua at 2007-7-15 2:30:22 >

OK, Maybe it's a problem with HTML as well. I attempted the following( note that it still refers to lowercase name even though I deleted it!):

C:\JAVATEMP>javac -d Trajectory.java

C:\JAVATEMP>javac -d Calculate.java

C:\JAVATEMP>appletviewer Trajectory.html

java.lang.NoClassDefFoundError: Trajectory (wrong name: trajectory)

at java.lang.ClassLoader.defineClass0(Native Method)

at java.lang.ClassLoader.defineClass(ClassLoader.java:502)

at java.security.SecureClassLoader.defineClass(SecureClassLoader.java:12

3)

at sun.applet.AppletClassLoader.findClass(AppletClassLoader.java:148)

at java.lang.ClassLoader.loadClass(ClassLoader.java:299)

at sun.applet.AppletClassLoader.loadClass(AppletClassLoader.java:114)

at java.lang.ClassLoader.loadClass(ClassLoader.java:255)

at sun.applet.AppletClassLoader.loadCode(AppletClassLoader.java:501)

at sun.applet.AppletPanel.createApplet(AppletPanel.java:566)

at sun.applet.AppletPanel.runLoader(AppletPanel.java:495)

at sun.applet.AppletPanel.run(AppletPanel.java:292)

at java.lang.Thread.run(Thread.java:536)

The appletviewer states "Start: applet not initialized"

This is the HTML for file Trajectory.html:

<html>

<Head>

</Head>

<Body>

<applet code = "Trajectory.class"

width = "600" height = "480"

>

Your browser is completely ignoring the <APPLET> tag!

</APPLET>

</Body>

</html>

analysis_gurua at 2007-7-15 2:30:22 >

Im not sure why this is appearing in your stack trace

Caused by: java.io.FileNotFoundException: C:\JAVATEMP\Trajectory\class.class (Th

e system cannot find the path specified)

This says that the appletviewer is looking for a directory called

Trajectory.

Does this exist in JAVATEMP? it may have been created by your use of the

However the problem is most likely cause by some mis-spelling somewhere

run del *.class

in your JAVATEMP directory then check the spelling of class names

and their corresponding directorys. Then recompile using javac *.java

(I'm assuming you only have the .java files for this project in this

directory.

Thats all the advice I can give for the moment. Its late and I need to

sleep. If you still have problems, I'll look at this thread again

tomorrow. (If you are lucky someone else may help before then though)

matfud

matfuda at 2007-7-15 2:30:23 >

Two ways of doing this

Use "static" i.e Instead of

boolean variableA, variableB

do as:

public static boolean variableA, variableB

By default if you don't put private or public in start, the

default is private which means "no other class" can use these

variables. We put static to "share the values" among more than one class

To access from AnalysisCalc, simply do:

Analysis.variableA;

Analysis.variableB;

Another way of doing this, is use "inner classes" which is a class

inside another class. The inner class can access the variables on the

outside class without using static: Example below:

public class Analysis extends JApplet implements ActionListener {

double variableX;

boolean variableA, variableB;

public class AnalysisCalc {

public AnalysisCalc(){

rundata( );

}

public void rundata( ) {

if (variableA == true) {

variableX = 100;

variableA = false;

}

variableX--;

}

}

}

akhalil100a at 2007-7-19 6:16:05 >

The current status of my code as of Oct. 1 7:30 AM Central Time is as following:

Trajectory.html>

<html>

<Head>

</Head>

<Body>

<applet code = "Trajectory.class"

width = "600" height = "480"

>

Your browser is completely ignoring the <APPLET> tag!

</APPLET>

</Body>

</html>

Trajectory.java >

// Trajectory Analysis Program: Trajectory.java

import java.awt.*;

import java.awt.event.*;

import javax.swing.*;

public class Trajectory extends JApplet implements ActionListener {

final double MAX = 90.0;

final double MIN = -90.0;

final double MAX_ALTITUDE = 2000000.0;

final double MIN_ALTITUDE = 0.0;

private JTextArea introductionArea, resultsArea;

private JLabel spanLabel, chordLabel,

thicknessLabel, massLabel, altitudeLabel, velocityLabel,

trajectory_angleLabel, time_incrementLabel, rotation_factorLabel,

calculationLabel, resultsLabel;

private JTextField spanField, chordField, thicknessField,

massField, altitudeField, velocityField, trajectory_angleField,

time_incrementField, rotation_factorField;

private JButton startButton, resetButton, contButton, abortButton;

String introduction_string, span_string, chord_string, thickness_string, mass_string,

altitude_string, velocity_string, trajectory_angle_string,

time_increment_string, rotation_factor_string, results_string;

public static double span, chord, thickness, mass, altitude, velocity, trajectory_angle, time_increment,

rotation_factor, distance, velocity_fps, elapsed_time;

public static boolean value, sentinel;

// create objects

public void init()

{

Calculate Z = new Calculate();

span = 0;

chord = 0;

thickness = 0;

mass = 0;

altitude = 0;

velocity = 0;

trajectory_angle = 0;

time_increment = 0;

rotation_factor = 0;

distance = 0;

velocity_fps = 0;

elapsed_time = 0;

velocity_fps = 0;

elapsed_time = 0;

value = true;

sentinel = true;

introduction_string =

"DEBRIS TRAJECTORY PROGRAM\n"

+ "designed by Weldon K. Chafin, Jr.\n\n"

+ "Inspired by the brave heroes of the Columbia Accident "

+ "of February 1, 2003.\n\n"

+ "This program determines trajectory for an object modeled "

+ "as a rectangular prism having given mass falling through "

+ "the atmosphere. The object is assumed to oscillate with same "

+ "frequency about all six possible permutations for axis "

+ "angular velocity vectors as the means to simulate "

+ "equally likely random events.\n\n"

+ "NOTE: This program is still under construction. "

+ "I predict this program will be fully functional by October 4, 2003. "

+ "Then it should have calculation capability comparable to the C++ program version I created "

+ "for the Columbia Accident Investigation Board (CAIB) to predict locations of Columbia debris. "

+ "In fact, the CAIB forwarded my program as an analytical tool to NASA "

+ "JSE Early Sightings Assessment Team tasked with finding high interest "

+ "Columbia debris items via radar imaging.";

span_string = "";

chord_string = "";

thickness_string = "";

mass_string = "";

altitude_string = "";

velocity_string = "";

trajectory_angle_string = "";

time_increment_string = "";

rotation_factor_string = "";

results_string = "";

// create container & panel

Container container = getContentPane();

Panel panel = new Panel( new FlowLayout( FlowLayout.LEFT));

container.add( panel );

// set up vertical boxlayout

Box box = Box.createVerticalBox();

Box inputbox1 = Box.createHorizontalBox();

Box inputbox2 = Box.createHorizontalBox();

Box inputbox2a = Box.createHorizontalBox();

Box inputbox2b = Box.createHorizontalBox();

Box inputbox2c = Box.createHorizontalBox();

Box inputbox2d = Box.createHorizontalBox();

Box inputbox3 = Box.createHorizontalBox();

Box buttonbox = Box.createHorizontalBox();

// set up introduction

introductionArea = new JTextArea( introduction_string, 10, 50 );

introductionArea.setEditable( false );

box.add( new JScrollPane( introductionArea ) );

box.add( Box.createVerticalStrut (10) );

box.add( inputbox1);

box.add(inputbox2a);

Dimension minSize = new Dimension(5, 15);

Dimension prefSize = new Dimension(5, 15);

Dimension maxSize = new Dimension(Short.MAX_VALUE, 15);

inputbox2a.add(new Box.Filler(minSize, prefSize, maxSize));

// set up span

spanLabel = new JLabel( "span (feet)" );

spanField = new JTextField(5 );

inputbox2a.add( spanLabel );

inputbox2a.add( spanField );

inputbox2a.add(new Box.Filler(minSize, prefSize, maxSize));

// set up chord

chordLabel = new JLabel( "chord (feet)" );

chordField = new JTextField(5 );

inputbox2a.add( chordLabel );

inputbox2a.add( chordField );

inputbox2a.add(new Box.Filler(minSize, prefSize, maxSize));

// set up thickness

thicknessLabel = new JLabel( "thickness (feet)" );

thicknessField = new JTextField(5 );

inputbox2a.add( thicknessLabel );

inputbox2a.add( thicknessField );

inputbox2a.add(new Box.Filler(minSize, prefSize, maxSize));

box.add( Box.createVerticalStrut (10) );

box.add(inputbox2b);

inputbox2b.add(new Box.Filler(minSize, prefSize, maxSize));

// set up mass

massLabel = new JLabel( "mass (slugs)" );

massField = new JTextField(5);

inputbox2b.add( massLabel );

inputbox2b.add( massField );

inputbox2b.add(new Box.Filler(minSize, prefSize, maxSize));

// set up altitude

altitudeLabel = new JLabel( "altitude (feet)");

altitudeField = new JTextField(5 );

inputbox2b.add( altitudeLabel );

inputbox2b.add( altitudeField );

inputbox2b.add(new Box.Filler(minSize, prefSize, maxSize));

// set up velocity

velocityLabel = new JLabel( "velocity (Mach Number)");

velocityField = new JTextField(5);

inputbox2b.add( velocityLabel );

inputbox2b.add( velocityField );

inputbox2b.add(new Box.Filler(minSize, prefSize, maxSize));

box.add( Box.createVerticalStrut (10) );

Dimension minSize2c = new Dimension(160, 15);

Dimension prefSize2c = new Dimension(160, 15);

Dimension maxSize2c = new Dimension(Short.MAX_VALUE, 15);

box.add(inputbox2c);

inputbox2c.add(new Box.Filler(minSize2c, prefSize2c, maxSize2c));

// set up trajectory_angle

trajectory_angleLabel = new JLabel( "trajectory angle (degrees)");

trajectory_angleField = new JTextField(5);

inputbox2c.add( trajectory_angleLabel );

inputbox2c.add( trajectory_angleField );

inputbox2c.add(new Box.Filler(minSize2c, prefSize2c, maxSize2c));

box.add( Box.createVerticalStrut (10) );

Dimension minSize2d = new Dimension(50, 15);

Dimension prefSize2d = new Dimension(50, 15);

Dimension maxSize2d = new Dimension(Short.MAX_VALUE, 15);

box.add(inputbox2d);

inputbox2d.add(new Box.Filler(minSize2d, prefSize2d, maxSize2d));

// set up time_increment

time_incrementLabel = new JLabel( "time increment (seconds)" );

time_incrementField = new JTextField(5);

inputbox2d.add( time_incrementLabel );

inputbox2d.add( time_incrementField );

inputbox2d.add(new Box.Filler(minSize2d, prefSize2d, maxSize2d));

// set up rotation_factor

rotation_factorLabel = new JLabel( "rotation factor (number)" );

rotation_factorField = new JTextField(5);

inputbox2d.add( rotation_factorLabel );

inputbox2d.add( rotation_factorField );

inputbox2d.add(new Box.Filler(minSize2d, prefSize2d, maxSize2d));

box.add( Box.createVerticalStrut (10) );

box.add( buttonbox);

Dimension minSizeB = new Dimension(10, 30);

Dimension prefSizeB = new Dimension(10, 30);

Dimension maxSizeB = new Dimension(Short.MAX_VALUE, 30);

buttonbox.add(new Box.Filler(minSizeB, prefSizeB, maxSizeB));

// set up start

startButton = new JButton( "START" );

buttonbox.add( startButton );

buttonbox.add(new Box.Filler(minSizeB, prefSizeB, maxSizeB));

// set up reset

resetButton = new JButton( "RESET" );

buttonbox.add( resetButton );

buttonbox.add(new Box.Filler(minSizeB, prefSizeB, maxSizeB));

// set up cont

contButton = new JButton( "CONTINUE" );

buttonbox.add( contButton );

buttonbox.add(new Box.Filler(minSizeB, prefSizeB, maxSizeB));

// set up abort

abortButton = new JButton( "ABORT" );

buttonbox.add( abortButton );

buttonbox.add(new Box.Filler(minSizeB, prefSizeB, maxSizeB));

box.add( Box.createVerticalStrut (10) );

// set up results

resultsArea = new JTextArea( results_string, 6, 50 );

resultsArea.setEditable( false );

box.add( new JScrollPane( resultsArea ) );

// add box to panel

panel.add( box );

// register event handlers

spanField.addActionListener( this );

chordField.addActionListener( this );

thicknessField.addActionListener( this );

massField.addActionListener( this );

altitudeField.addActionListener( this );

velocityField.addActionListener( this );

trajectory_angleField.addActionListener( this );

time_incrementField.addActionListener( this );

rotation_factorField.addActionListener( this );

startButton.addActionListener( this );

resetButton.addActionListener( this );

contButton.addActionListener( this );

abortButton.addActionListener( this );

reset();

} // end method init

public void t_r_a_test (double trajectory_angle) throws Tare {

if (trajectory_angle > MAX || trajectory_angle < MIN)

throw new Tare("\ntrajectory_angle "

+ trajectory_angle + " is outside of allowable range\n\n"

+ "Try another value for the trajectory angle\n"

+ "( " + MIN + " <= trajectory angle <= " + MAX + " )" );

} // end method t_r_a_test

public void a_r_e_test (double altitude) throws Are {

if ( altitude > MAX_ALTITUDE )

throw new Are("\naltitude "

+ altitude + " is outside of allowable range\n\n"

+ "Try value for altitude\n"

+ "( " + MIN_ALTITUDE + " <= altitude <= "

+ MAX_ALTITUDE + " )" );

} // end method a_r_e_test

public void n_v_test (boolean value) throws Nve {

if ( value == false ){

if( span < 0 ){

span = 0;

throw new Nve("\nValue for "

+ " span must not be negative\n\n"

+ "Try another value ");

}

if( chord < 0 ){

chord = 0;

throw new Nve("\nValue for "

+ " chord must not be negative\n\n"

+ "Try another value ");

}

if( thickness < 0 ){

thickness = 0;

throw new Nve("\nValue for "

+ " thickness must not be negative\n\n"

+ "Try another value ");

}

if( mass < 0 ){

mass = 0;

throw new Nve("\nValue for "

+ " mass must not be negative\n\n"

+ "Try another value ");

}

if( altitude < 0 ){

altitude = 0;

throw new Nve("\nValue for "

+ " altitude must not be negative\n\n"

+ "Try another value ");

}

if( velocity < 0 ){

velocity = 0;

throw new Nve("\nValue for "

+ " velocity must not be negative\n\n"

+ "Try another value ");

}

if( time_increment < 0 ){

time_increment = 0;

throw new Nve("\nValue for "

+ " time increment must not be negative\n\n"

+ "Try another value ");

}

if( rotation_factor < 0 ){

rotation_factor = 0;

throw new Nve("\nValue for "

+ " rotation factor must not be negative\n\n"

+ "Try another value ");

}

} //end if( value == false )

} // end method n_v_test

// process events

public void actionPerformed( ActionEvent event )

{

// process spanField

if( event.getSource() == spanField ) {

span_string = spanField.getText();

span = Double.parseDouble( span_string);

}

// process chordField

if( event.getSource() == chordField ) {

chord_string = chordField.getText();

chord = Double.parseDouble( chord_string);

}

// process thicknessField

if( event.getSource() == thicknessField ) {

thickness_string = thicknessField.getText();

thickness = Double.parseDouble( thickness_string);

}

// process massField

if( event.getSource() == massField ) {

mass_string = massField.getText();

mass = Double.parseDouble( mass_string);

}

// process altitudeField

if( event.getSource() == altitudeField ){

altitude_string = altitudeField.getText();

altitude = Double.parseDouble( altitude_string);

}

// process velocityField

if( event.getSource() == velocityField ){

velocity_string = velocityField.getText();

velocity = Double.parseDouble( velocity_string);

}

// process trajectory_angleField

if( event.getSource() == trajectory_angleField ){

trajectory_angle_string = trajectory_angleField.getText();

trajectory_angle = Double.parseDouble( trajectory_angle_string);

}

// process time_incrementField

if( event.getSource() == time_incrementField ){

time_increment_string = time_incrementField.getText();

time_increment = Double.parseDouble( time_increment_string);

}

// process rotation_factorField

if( event.getSource() == rotation_factorField ){

rotation_factor_string = rotation_factorField.getText();

rotation_factor = Double.parseDouble( rotation_factor_string);

}

// process startButton event

if ( event.getSource() == startButton )

strtb();

// process resetButton event

if ( event.getSource() == resetButton )

reset();

// process contButton event

if ( event.getSource() == contButton )

cont();

// process abortButton event

if ( event.getSource() == abortButton )

abort();

} // end method actionPerformed

public void strtb()

{

try{

span = Double.parseDouble( spanField.getText() );

chord = Double.parseDouble( chordField.getText() );

thickness = Double.parseDouble( thicknessField.getText() );

mass = Double.parseDouble( massField.getText() );

altitude = Double.parseDouble( altitudeField.getText());

velocity = Double.parseDouble( velocityField.getText());

trajectory_angle = Double.parseDouble( trajectory_angleField.getText());

time_increment = Double.parseDouble( time_incrementField.getText() );

rotation_factor = Double.parseDouble( rotation_factorField.getText() );

if( span < 0 || chord < 0 || thickness < 0 || mass < 0

|| altitude < 0 || velocity < 0

|| time_increment < 0 || rotation_factor < 0 )

value = false;

t_r_a_test( trajectory_angle );

n_v_test( value );

a_r_e_test( altitude );

while(sentinel){

Z.rundata(this);

if( altitude < 10 )

sentinel = false;

}

results();

resultsArea.setText( results() );

}//end try

// process improperly formatted input

catch ( NumberFormatException numberFormatException ) {

JOptionPane.showMessageDialog( this,

"You must enter numbers in decimal format or integers",

"Invalid Number Format" ,

JOptionPane.ERROR_MESSAGE );

} // end catch NumberFormatException

catch ( ArithmeticException arithmeticException ) {

JOptionPane.showMessageDialog( this,

arithmeticException.toString(), "Arithmetic Exception" ,

JOptionPane.ERROR_MESSAGE );

} // end catch ArithmeticException

catch ( Tare tare ) {

JOptionPane.showMessageDialog( this,

tare.toString(), "-90 <= range <= 90 " ,

JOptionPane.ERROR_MESSAGE );

} // end catch Tare

catch ( Nve nve ) {

JOptionPane.showMessageDialog( this,

nve.toString(), " value less than zero" ,

JOptionPane.ERROR_MESSAGE );

} // end catch Nve

catch ( Are are ) {

JOptionPane.showMessageDialog( this,

are.toString(), " value greater than maximum" ,

JOptionPane.ERROR_MESSAGE );

} // end catch Are

} // end method strtb

public void reset()

{

span_string = "";

chord_string = "";

thickness_string = "";

mass_string = "";

altitude_string = "";

velocity_string = "";

trajectory_angle_string = "";

time_increment_string = "";

rotation_factor_string = "";

results_string = "";

spanField.setText( span_string );

chordField.setText( chord_string );

thicknessField.setText( thickness_string );

massField.setText( mass_string );

altitudeField.setText( altitude_string );

velocityField.setText( velocity_string );

trajectory_angleField.setText( trajectory_angle_string );

time_incrementField.setText( time_increment_string );

rotation_factorField.setText( rotation_factor_string );

resultsArea.setEditable( true );

resultsArea.setText( results_string );

resultsArea.setEditable( false );

span = 0;

chord = 0;

thickness = 0;

mass = 0;

altitude = 0;

velocity = 0;

trajectory_angle = 0;

time_increment = 0;

rotation_factor = 0;

distance = 0;

velocity_fps = 0;

elapsed_time = 0;

value = true;

}// end method reset

public void cont()

{

//later

}

public void abort()

{

//later

}

public String results()

{

results_string =

"Distance =\t\t" + distance + " miles\n"

+ "Altitude =\t\t" + altitude + " feet\n"

+ "Trajectory Angle =\t" + trajectory_angle + " degrees\n"

+ "Velocity =\t\t" + velocity_fps + " feet per second\n"

+ "Elapsed Time =\t\t" + elapsed_time + " seconds\n";

return results_string;

}

} //end class Trajectory

Calculate.java >

// Trajectory Analysis Program: Calculate.java

public class Calculate {

// Calculate constructor

public Calculate()

{

rundata( );

}

public void rundata( Trajectory T)

{

T.altitude--;

}

} // end class Calculate

Nve.java ->

// Trajectory Analysis Program: Nve.java

import java.awt.event.*;

public class Nve extends Exception{

public Nve (){ }

public Nve (String msg)

{ super(msg); }

} // end class Nve

Tare.java ->

// Trajectory Analysis Program: Tare.java

import java.awt.event.*;

public class Tare extends Exception{

public Tare (){ }

public Tare (String msg)

{ super(msg); }

} // end class Tare

Are.java ->

// Trajectory Analysis Program: Are.java

import java.awt.event.*;

public class Are extends Exception{

public Are (){ }

public Are (String msg)

{ super(msg); }

} // end class Are

analysis_gurua at 2007-7-19 6:16:05 >

Calculate.java:10: rundata(Trajectory) in Calculate cannot be applied to ()

rundata( );

^

The rundata method takes one argument. You have not supplied any, nor does there seem to be a valid reason for calling it here.

Trajectory.java:539: cannot resolve symbol

symbol : variable Z

location: class Trajectory

Z.rundata(this);

^

The only occurance of the Z variable is in another method. If you wish to make it visible to more than one method, make it a field.

Why is it called 'Z' anyway? How would you know what Nve means without look *** at the source of the method that throws it? The only additional information added to the exception class by the Nve subclass is the type, and the label of the type is almost meaningless, and you have to break encapsulation to get any meaning.

Normally you obsfucate Java after you compile it.

classes.methods.and.variables.should.have.meaningful.names.

Why is the presentation and trajectory state in one class, but the trajectory claculation method in another? Either put everything in one if you don't want to take advantage of OOD, or break up the functionality sensibly, so the dynamics updates a state vector (if you need to use different dynamics models), which is then presented by something else, in the first instance an applet.

Pete

Pete_Kirkhama at 2007-7-19 6:16:05 >

> "Why is the presentation and trajectory state in one

> class, but the trajectory calculation method in

> another? Either put everything in one if you don't

> want to take advantage of OOD, or break up the

> functionality sensibly, so the dynamics updates a

> state vector (if you need to use different dynamics

> models), which is then presented by something else, in

> the first instance an applet."

>

> I could put it all into the Trajectory class, but I

> striving for easier code maintenance.

You are misunderstanding Pete's recommendation.

His (and my) opinion are that, as structured, your code is less maintainable than if it were in one file.

Therefore:

DO THIS -

A) put all the code in one class

OR THIS -

B) seperate ALL the calculation data from the applet, and combine it with the calculation code. Then have the applet ask the data/calculation code class for the values when it wants to display them

Think of it this way, if all the data and calculation code is in one class; that class can be tested and verified without messing around with the UI.

larsonaa at 2007-7-19 6:16:05 >

> Pete:

>

> "If the browser completely ignores the applet tag,

> won't this display as 'Your browser is completely

> ignoring the tag!' ?"

>

>

> Sure it will display it if my browser isn't compatible

> with the HTML. I put it there as good programming

> practice since some browsers may not support the code.

> It provides a message if that scenario occurs so the

> problem can be understood. It doesn't harm anything.

The point was that the message includes the applet tag which the browser ignores. So the important part of the message, what tag is ignored, is not presented to the user. Furthermore, it is not valid HTML to have applet tags within applet tags.

A message saying 'Your browser is completely ignoring the tag' is less meaningful than, for example, 'Your browser is completely ignoring the <i>applet</i> tag' or, assuming the reader would be looking at the page's source code if they cared about tags, 'Your browser doen't not appear to support embedded Java content'.

Pete

Pete_Kirkhama at 2007-7-19 6:16:05 >