File I/O handling
FileInputStream fle =new FileInputStream("test.txt");
java.io.BufferedReader inFile =new java.io.BufferedReader(new java.io.InputStreamReader(fle));
String cm ="";
p.load(fle);//p - Properties class object
while((cm = inFile.readLine()) !=null){
System.out.println(p.getProperty("key"));
}
fle.close();
In the above code i am using Properties to display property name "key". But i dont know why its not getting inside loop itself. Please suggest me.
[834 byte] By [
ArpanaKa] at [2007-11-27 11:23:37]
Probably because readLine() returns null. Or you get an exception that you ignore.
> Probably because readLine() returns null. Or you get
> an exception that you ignore.
No, file is not empty . It has data. That code is inside try/catch block and in catch block i am printing stack trace. Nothing shows error.
Try
while (true) {
String line = in.readLine();
if (line == null) {
break;
}
// ....
}
Maybe with a system.out.println() or debugger breakpoint for verification. You can change it back later.
If i ignore "p.load(fle)" line, then it works. But i really need that line. Any help
> Try
>
> [code]while (true) {
>String line = in.readLine();
> if (line == null) {
>break;
>
>// ....
> /code]
>
> Maybe with a system.out.println() or debugger
> breakpoint for verification. You can change it back
> later.
I tried it. Indeed its returning null. But where as file is not empty. How to solve the problem
Reopen the file. You're trying to read 1 file 2 times. The BufferedReader will never see the data in the file, since the p.load() empties the fileinputstream.
public void printDetails() throws IOException {
FileInputStream fin = new FileInputStream(propertyFileName);
properties.load(fin);
System.out.println(properties.get("permission"));
Enumeration enum = properties.propertyNames();
String key = "";
while(enum.hasMoreElements()) {
key = (String)enum.nextElement();
System.out.println(" Key : " + key + " Value : " + properties.get(key));
}
}
This may be helpful for you.
> Reopen the file. You're trying to read 1 file 2
> times. The BufferedReader will never see the data in
> the file, since the p.load() empties the
> fileinputstream.
Please tell me when to reopen the file. It is after p.load() method or inside while loop
Actually what i am trying to do is,
1. Load the inputstream in properties and later retrieve property value
2. Read the file line by line and check for a matching property name
Hope I am clear ,
Thanks Joni, now I see it as well. You "use up" your file stream when loading the properties. trying to read anything afterwards will not result in anything.
Don't use the same stream to read the file and to load the properties.
> > public void printDetails() throws IOException {
>
> FileInputStream fin = new
> ew FileInputStream(propertyFileName);
> properties.load(fin);
>
> System.out.println(properties.get("permission"));
> Enumeration enum = properties.propertyNames();
> String key = "";
> while(enum.hasMoreElements()) {
> key = (String)enum.nextElement();
> System.out.println(" Key : " + key + " Value : " +
> " + properties.get(key));
> }
>
> }
>
>
> This may be helpful for you.
Thanks Santhiya. Your code helped me . Bad me. I was trying to read a single file 2 times just for match checking. Above code worked out. thanks
Thanks to others who helped me by pointing towards my mistake
What was the purpose of the exercise? to test Properties.load()? Sun having been doing that every build for ten years, you don't need to do that yourself.
ejpa at 2007-7-29 15:01:44 >
