Thread: 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);

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.

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

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

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

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.

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,

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