Launch 3 threads and print them all inside a JTextArea
Can't figured it out :Sinstead of using the console , i want to do the same but in a JTextArea
import java.awt.BorderLayout;
import java.awt.Container;
import javax.swing.JFrame;
import javax.swing.JTextArea;
publicclass ThreadTArea{
publicstaticvoid main(String[] args){
Interface inter =new Interface();
inter.execute();
PrintChar2 letra_a =new PrintChar2('a', 100, inter);
PrintChar2 letra_b =new PrintChar2('b', 100, inter);
PrintNum2 numero =new PrintNum2(100, inter);
letra_a.start();
numero.start();
letra_b.start();
}
}
class PrintChar2extends Thread{
privatechar letra;
privateint times;
Interface inter;
public PrintChar2(char letra,int times, Interface inter){
this.letra = letra;
this.times = times;
inter =new Interface();
}
publicvoid run(){
for(int i = 1; i <= times; i++){
// Print into the TextArea
try{
Thread.sleep(1000);
}catch(InterruptedException e){ e.printStackTrace();}
}
}
}
class PrintNum2extends Thread{
privateint times;
Interface inter;
public PrintNum2(int times, Interface inter){
this.times = times;
inter =new Interface();
}
publicvoid run(){
for(int i = 1; i <= times; i++){
try{
Thread.sleep(1000);
}catch(InterruptedException e){ e.printStackTrace();}
}
}
}
class Interface{
public Interface(){
Container c = frame.getContentPane();
c.setLayout(new BorderLayout());
frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
c.add(area, BorderLayout.CENTER);
}
private JFrame frame =new JFrame("Result");
private JTextArea area =new JTextArea();
publicvoid printThreads(....){
//Maybe this is not necessary
}
publicvoid execut(){
frame.pack();
frame.setLocation(300,300);
frame.setVisible(true);
}
}
Thanks
# 1
Swing isn't thread safe, you need to update the contents of the text area on the event thread.
# 2
Hm
1. don't extend Thread, implement Runnable
2. 'Interface' is possibly the worst name for a class I can think of
3. Swing has a single event thread (which is not the main thread and certainly not any other thread you choose to start) and you need to access Swing objects on that thread only - see http://java.sun.com/products/jfc/tsc/articles/threads/threads1.html
4. your threads aren't doing anything useful, are we supposed to guess what you want to happen?
Still, at least you're not extending JFrame so have a biscuit.
# 3
Ok, I'm feeling generous, or insane... But if you take a look at the code below, you should be able to easily finish your own homework.
I would strongly suggest you check up everything that you don't understand using google, or the link that itchy provided.
package jdc;
import java.awt.BorderLayout;
import java.awt.Container;
import java.awt.Dimension;
import javax.swing.JFrame;
import javax.swing.JTextArea;
import javax.swing.SwingUtilities;
public class TestMutlitpleThreads {
private final JFrame frame = new JFrame("Result");
private final JTextArea textArea = new JTextArea();
public static void main(String[] args) {
TestMutlitpleThreads test = new TestMutlitpleThreads();
StringAppender appender1 = new StringAppender("a", 10, test);
StringAppender appender2 = new StringAppender("b", 10, test);
Thread t1 = new Thread(appender1, "Thread 1");
t1.start();
Thread t2 = new Thread(appender2, "Thread 2");
t2.start();
}
public TestMutlitpleThreads() {
this.textArea.setLineWrap(true);
this.frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
this.frame.setLocation(300, 300);
this.frame.setSize(new Dimension(100, 100));
this.frame.setVisible(true);
Container c = this.frame.getContentPane();
c.setLayout(new BorderLayout());
c.add(textArea, BorderLayout.CENTER);
}
public void appendString(final String toAppend) {
SwingUtilities.invokeLater(new Runnable() {
@SuppressWarnings("synthetic-access")
public void run() {
TestMutlitpleThreads.this.textArea.append(toAppend);
}
});
}
}
final class StringAppender implements Runnable {
private TestMutlitpleThreads test;
private int repeatCount;
private String toAppend;
public StringAppender(String str, int numberOfTimesToRepeat, TestMutlitpleThreads test) {
if (str == null || str.trim().length() == 0) {
throw new IllegalArgumentException("You must specify a String to display");
}
this.toAppend = str;
this.repeatCount= numberOfTimesToRepeat;
this.test = test;
}
public void run() {
for (int i = 0; i < this.repeatCount; ++i) {
try {
this.test.appendString(toAppend);
Thread.sleep(500);
} catch (InterruptedException e) {
e.printStackTrace();
}
}
}
}
Hmmm, you may need the synchronised keyword on the appendString method. I'll leave that to someone with a better understanding to help out.
# 4
solved.
I did it only with three classes...(Interface class as the main class)
here is the final code, thanks everyone
Why to complicate something that can be easy :) , that's my problem, i think to much when the answer is rigtht there lol
import java.awt.BorderLayout;
import java.awt.Container;
import javax.swing.JFrame;
import javax.swing.JTextArea;
public class ThreadTArea {
public static void main(String[] args) {
JFrame frame = new JFrame("Result");
JTextArea area = new JTextArea();
Container c = frame.getContentPane();
c.setLayout(new BorderLayout());
frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
c.add(area, BorderLayout.CENTER);
PrintChar2 letra_a = new PrintChar2('a', 100, area);
PrintChar2 letra_b = new PrintChar2('b', 100, area);
PrintNum2 numero = new PrintNum2(100, area);
frame.setLocation(300,300);
frame.setSize(300,450);
frame.setVisible(true);
letra_a.start();
numero.start();
letra_b.start();
}
}
class PrintChar2 extends Thread{
private char letra;
private int times;
JTextArea area;
public PrintChar2(char letra, int times, JTextArea area) {
this.letra = letra;
this.times = times;
this.area = area;
}
public void run(){
for(int i = 1; i <= times; i++){
area.append(Character.toString(letra)); // Print into the TextArea
area.setLineWrap(true);
try{
Thread.sleep(100);
}catch(InterruptedException e){ e.printStackTrace();}
}
}
}
class PrintNum2 extends Thread{
private int times;
JTextArea area;
public PrintNum2(int times, JTextArea area) {
this.times = times;
this.area = area;
}
public void run() {
for(int i = 1; i <= times; i++){
area.append(" "+Integer.toString(i));
area.setLineWrap(true);
try{
Thread.sleep(50);
}catch(InterruptedException e){ e.printStackTrace();}
}
}
}
Message was edited by:
Java__Estudante
# 5
You ignored itchy and scratchy
You ignored me.
Let's try it one more time.
Swing is NOT thread safe, you cannot update a swing component on a random thread that you created. If you scroll back up, you will see that I gave you the code to use, free of charge, at no cost to you other than to actually read it.
Don't bother coming back to us asking why your multi-threaded application is hanging.
It is bad practice to extend Thread, you should implement the runnable interface instead. I would also suggest that you use named threads, it will make your debugging much simpler (what am I thinking, you won't bother debugging, you will just dump your code here, and ask for it to be fixed).
