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Thread: Output problem (newbie)

  1. #1
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    Default Output problem (newbie Q)

    Hello. I am learning java and tried to make a simple program, which reads the int number and writes it into a file. The problem is - the txt file remains empty. Take a look at the code:

    import java.io.*;
    import java.util.*;
     
    class Job {
    	int x;
     
    	public int inputTxt() {
    		try {
    			x = System.in.read();
    		} catch (Exception e) {
    			System.out.println("input error");	
    		}
    		return x;
    	}
     
    	public void outputF() {
    		try {
    			OutputStream f = new FileOutputStream("test.txt");
    			f.write(x);
    		} catch (Exception e) {
    			System.out.println("output error");	
    		}
    	}
     
    	public void closeF() {
    		try {
    			OutputStream f = new FileOutputStream("test.txt");
    			f.close();
    		} catch (Exception e) {
    			System.out.println("close error");	
    		}
    	}
    }
     
    class Test {
    	public static void main(String args [ ]) {
    		Job j = new Job();
    		j.inputTxt();
    		j.outputF();
    		j.closeF();
    	}
    }
    Last edited by Asido; June 8th, 2010 at 11:56 AM.


  2. #2
    Super Moderator Norm's Avatar
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    Default Re: Output problem (newbie)

    The f object in the close method is NOT the same as the f object in the write method.
    Close the output file after writing to it or have a reference to the object that was written to when closing it.
    txt file remains empty
    What is the size of the output file? Is it 0? What does the write() method output to the file?
    Look at the file with a hex editor.
    Last edited by Norm; June 8th, 2010 at 11:57 AM.

  3. The Following User Says Thank You to Norm For This Useful Post:

    Asido (June 8th, 2010)

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    Default Re: Output problem (newbie)

    Quote Originally Posted by Norm View Post
    The f object in the close method is NOT the same as the f object in the write method.
    Close the output file after writing to it or have a reference to the object that was written to when closing it.

    What is the size of the output file? Is it 0? What does the write() method output to the file?
    Look at the file with a hex editor.
    Ok, I go it, thanks a lot!
    Yes, the txt file had 0 b size.

  5. #4
    Super Moderator Norm's Avatar
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    Default Re: Output problem (newbie)

    I got output (1 byte) when I ran your code (except I moved the close to the outputF() method).

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    Default Re: Output problem (newbie)

    Quote Originally Posted by Norm View Post
    I got output (1 byte) when I ran your code (except I moved the close to the outputF() method).
    I did the same and it solved the problem.

  7. #6
    Super Moderator Norm's Avatar
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    Default Re: Output problem (newbie)

    I guess what happened is you created a file and wrote to it. Then in the closeF() method you created a new file with the same name and wrote nothing to it destroying the first version.

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    Asido (June 8th, 2010)

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