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Thread: Java for loop problem and out put is not coming

  1. #1
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    Default Java for loop problem and out put is not coming

    Hello everyone,
    I have a code bit where the program takes ages to complete for some reason and i have a quad processor.
    The code is below; "allPossibleCombinationsOutput" is a String and maxBuffer is an int but when i get it above 1500, the program responds after 10secs of lockup and i need the number to be above 200000. What can i do? Thanks for your time.


    for (int y = 0; y < maxBuffer; y++) {
                allPossibleCombinationsOutput += "" + (y + 1);
                for (int x = 1; x < 7; x++) {
                    allPossibleCombinationsOutput += "\t" + allPossibleGuesses[y][x];
                }
                allPossibleCombinationsOutput += "\n";    
            }
            jTextPane3.setText(allPossibleCombinationsOutput);


  2. #2
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    Default Re: no response loop problem

    Hello thewonderdude and welcome to the Java Programming Forums.

    What does this code do exactly?

    Is it possible to post all your code so I can attempt to compile it?
    Please use [highlight=Java] code [/highlight] tags when posting your code.
    Forum Tip: Add to peoples reputation by clicking the button on their useful posts.

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  3. #3
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    Default Re: no response loop problem

    public void allPossibleCombinations(int array3[][]) {
     
            boolean yes = true;
            int cn[] = new int[7];
            Random generator = new Random();
            int z = 0, i = 1;
     
            for (int dummy = 0; dummy < 7; dummy++) {
                cn[dummy] = 0;
            }
            while (z < maxBuffer) {
                if (array3[1][cn[1]] < array3[2][cn[2]] && array3[2][cn[2]] < array3[3][cn[3]] && array3[3][cn[3]] < array3[4][cn[4]] && array3[4][cn[4]] < array3[5][cn[5]] && array3[5][cn[5]] < array3[6][cn[6]]) {
     
                    allPossibleGuesses[z][1] = array3[1][cn[1]];
                    allPossibleGuesses[z][2] = array3[2][cn[2]];
                    allPossibleGuesses[z][3] = array3[3][cn[3]];
                    allPossibleGuesses[z][4] = array3[4][cn[4]];
                    allPossibleGuesses[z][5] = array3[5][cn[5]];
                    allPossibleGuesses[z][6] = array3[6][cn[6]];
     
                    z++;
                }
                i = generator.nextInt(6) + 1;
                if (cn[i] == 25) {
                    cn[i] = 0;
                } else {
                    cn[i]++;
                }
                while (yes) {
                    i = generator.nextInt(6) + 1;
                    if (cn[i] == 25) {
                        cn[i] = 0;
                    } else {
                        cn[i]++;
                    }
                    yes = generator.nextBoolean();
                 }
                yes = generator.nextBoolean();
            }
            for (int a = 0; a < maxBuffer; a++) {
                for (int b = 0; b < maxBuffer; b++) {
                    if (allPossibleGuesses[a][1] == allPossibleGuesses[b][1] && allPossibleGuesses[a][2] == allPossibleGuesses[b][2] && allPossibleGuesses[a][3] == allPossibleGuesses[b][3] && allPossibleGuesses[a][4] == allPossibleGuesses[b][4] && allPossibleGuesses[a][5] == allPossibleGuesses[b][5] && allPossibleGuesses[a][6] == allPossibleGuesses[b][6] && a != b) {
                        allPossibleGuesses[a][1] = 0;
                        allPossibleGuesses[a][2] = 0;
                        allPossibleGuesses[a][3] = 0;
                        allPossibleGuesses[a][4] = 0;
                        allPossibleGuesses[a][5] = 0;
                        allPossibleGuesses[a][6] = 0;
                    }
                }
            }
            allPossibleCombinationsOutput += "G#\tFirstP\tSecondP\tThirdP\tFourthP\tFifthP\tSixthP\n--------------------------------------------------------------------------------------------------------------------------\n\n";
    [COLOR="Red"]        for (int y = 0; y < maxBuffer; y++) {
                allPossibleCombinationsOutput += "" + (y + 1);
                for (int x = 1; x < 7; x++) {
                    allPossibleCombinationsOutput += "\t" + allPossibleGuesses[y][x];
                }
                allPossibleCombinationsOutput += "\n";    
            }
            jTextPane3.setText(allPossibleCombinationsOutput);
        }[/COLOR]

    For this method to work, i have to use a number around 1500 for `maxBuffer`.

    This is the whole method where the problem is. I'm not comfortable with java yet as you can see but the problem seems to be the from the part i sent earlier(shown here red). This method randomly increases 1 or more up to 6 numbers to create 6 numbered combination up to the limit of the "maxBuffer" which needs to be above 200000. Fills 0 to a combination if it has the same numbers with another one. Last part just prints the whole combination set.
    The (int array3[][]) parameter holds numbers for 6 places. i.e array3[1][25] means 25th number from the list of numbers for 1 st position.
    Thanks for the effort.

  4. #4

    Default Re: no response loop problem

    Please can you write allPossibleGuesses and array3 declarations and their initialization too ?
    Last edited by leandro; March 11th, 2009 at 01:35 PM.

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    Default Re: no response loop problem

    int allPossibleGuesses[][] = new int[maxBuffer][7];
    int[][] holder = new int[7][750];
    holder is sent to the method;
    allPossibleCombinations(holder);

    holder has int values sorted. holder[1][12]-->means 1st position 12th number. in the method i sent previously, it is being used as array3. The 'allPossibleGuesses' gets values from the previously mentioned method.

    thanks in advance

  6. #6
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    Default Re: no response loop problem

    hello,
    i put notifiers to check what is happening and at the code which i wrote at my first post, the program processes quite quickly up to y= 5000 where i can see a definite slowdown of performance when in 100000 i can actually count the System.out.println("alive and well "+y) results 'n the console.

     for (int y = 0; y < maxBuffer; y++) {
                allPossibleCombinationsOutput += "" + (y + 1);
                for (int x = 1; x < 7; x++) {
                    allPossibleCombinationsOutput += "\t" + allPossibleGuesses[y][x];
                }
               [COLOR="Red"] System.out.println("alive and well  "+y);[/COLOR]
                allPossibleCombinationsOutput += "\n";    
            }
     jTextPane3.setText(allPossibleCombinationsOutput);

    is there someway to speed up the process vastly or theres no hope for this?
    thanks

  7. #7

    Default Re: no response loop problem

    Hello, let me do some test but if you iterate over 200000 it will take time

  8. #8

    Default Re: no response loop problem

    Sorry for the delay. I did some test, you can do some optimizations in your code. But working with a big matrix will implicate lot of time.

    A simple opotimization is using StringBuffer instead of String. Try this code and see the difference:

                  private StringBuffer allPossibleCombinationsOutput = new StringBuffer();
    	      private String allPossibleCombinationsOutput2 = new String();
    	      private int maxBuffer = 1000;
    	     private int allPossibleGuesses[][] = new int[maxBuffer][7];
     
            public void bb() {
    		Date d = new Date();
    		for (int i = 0; i < maxBuffer; i++)
    			for (int j = 0; j < 7; j++)
    				allPossibleGuesses[i][j] = 22;
    		for (int i = 0; i < maxBuffer; i++)
    			for (int j = 0; j < 7; j++)
    				System.out.println(allPossibleGuesses[i][j]);
    		for (int y = 0; y < maxBuffer; y++) {
    			allPossibleCombinationsOutput2 += "" + (y + 1);
    			for (int x = 1; x < 7; x++) {
    				allPossibleCombinationsOutput2 += "\t"
    						+ allPossibleGuesses[y][x];
    			}
    			System.out.println("alive and well  " + y);
    			allPossibleCombinationsOutput2 += "\n";
    		}
    		System.out.print(allPossibleCombinationsOutput2);
    		long diff = new Date().getTime() - d.getTime();
    		System.out.println(diff + " ms");
    	}
     
    	public void aa() {
    		Date d = new Date();
    		for (int i = 0; i < maxBuffer; i++)
    			for (int j = 0; j < 7; j++)
    				allPossibleGuesses[i][j] = 22;
    		for (int i = 0; i < maxBuffer; i++)
    			for (int j = 0; j < 7; j++)
    				System.out.println(allPossibleGuesses[i][j]);
    		for (int y = 0; y < maxBuffer; y++) {
    			allPossibleCombinationsOutput.append("" + (y + 1));
    			for (int x = 1; x < 7; x++) {
    				allPossibleCombinationsOutput.append("\t"
    						+ allPossibleGuesses[y][x]);
    			}
    			System.out.println("alive and well  " + y);
    			allPossibleCombinationsOutput.append("\n");
    		}
    		System.out.print(allPossibleCombinationsOutput);
    		long diff = new Date().getTime() - d.getTime();
    		System.out.println(diff + " ms");
    	}

    If you run the 2 methods you will see the differences in time (diff in miliseconds). This is a simple way to check the run time with Date.

    About using a matrix of 20000 rows, it will take time and I don't think if it is anything to do.

    Hope this help you. Let me know how it goes please.

  9. #9
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    Default Re: no response loop problem

    almost made it to 500000 in 3 minutes but gave an error;

    Exception in thread "AWT-EventQueue-0" java.lang.OutOfMemoryError: Java heap space

    after alive and well 474214,
    very fast and much better then the last time considering it could get up to 2000
    thank you,

  10. #10

    Default Re: no response loop problem

    Try increasing the maximum allowed heap space as explained in the instructions at this page:
    How do I increase the heap space for the Java VM in MATLAB 6.0 (R12) and later versions? - 1-18I2C

    This is a sample using 328 Mb of ram:

    java -Xmx382M -jar myjar.jar

    java -Xmx382M myClass

    Best regards

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