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Thread: How do you sort an array? [using bubble sort]

  1. #1
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    Default How do you sort an array? [using bubble sort]

    Here's my code:
    import java.util.*;
     
    class array1{
    	public static void main(String args[]){
    		Random number = new Random();
     
    		int num[] = new int[100];
     
    		// filling array with random numbers
    		for(int i=0;i<100;i++){
    			int randomnumber = 10+number.nextInt(89);
    			num[i] = randomnumber;
    			System.out.print(num[i]+" ");
    		}
                    // Sorting the array
    		for(int i=0;i<100;i++){
    			for(int j=0;j<100;j++){
    				if(num[j]>num[j+1]){
    					num[j]=num[j+1];
    					num[j+1]=num[j];
     
    				}
    			}
    		}
    	}
    }
    What should I put after the "num[j+1]=num[j]"?


  2. #2
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    Default Re: How do you sort an array? [using bubble sort]

    This:
    num[j]=num[j+1];
    num[j+1]=num[j];
    Will not swap values. For example, let's say:
    num[j]=10
    num[j+1]=12
    After we run the first line of code, the values become:
    num[j]=12
    num[j+1]=12
    And after we run the second line of code, the values stay:
    num[j]=12
    num[j+1]=12

    Why? Because we never "remembered" the previous value of num[j]
    Instead, you want to:
    1. Store the value of num[j] in a variable (int var, for example)
    2. Do the first line of code from earlier
    3. Instead of the second line of code, we want: num[j+1] = var;

    Does that make sense?
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