bnrfly - 2 years ago 70

Java Question

I just want to write a program that sorts 3 integers. The integers are entered from the input dialog. My code is really simple. I just need to get some data and put them in array called

`num`

`sort`

`System.out.println("Sorted Result : "+Arrays.toString(num))`

The output just let me input data and then nothing happen.

Can anyone please tell me something I miss or what I did wrong?

Thank you.

`package numThree;`

import java.util.Scanner;

import java.util.Arrays;

public class sort {

public static void main(String[] args) {

Scanner sc = new Scanner(System.in);

int[] num = new int[3];

//INPUT DATA

System.out.println("Enter integers : ");

for(int i=0;i<=num.length;i++){

num[i]=sc.nextInt();

}

sort(num);

}

//SORTING

public static void sort (int[] num){

for(int i=0;i<=num.length-1;i++){

for(int j=0;j<=num.length-i;j++){

if(num[j-1]>num[j]){

int temp = num[j];

num[j] = num[j-1];

num[j-1] = temp;

}

}

System.out.println("Sorted Result : "+Arrays.toString(num));

}

}

}

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Answer Source

I believe you need a boolean flag to implement a bubble sort as you cannot know in advance how many times the loop will perform the swapping of consecutive elements.

Try this:

```
package numThree;
import java.util.Scanner;
import java.util.Arrays;
public class sort {
public static void main(String[] args) {
Scanner sc = new Scanner(System.in);
int[] num = new int[3];
//INPUT DATA
System.out.println("Enter integers : ");
for(int i=0;i<=num.length;i++){
num[i]=sc.nextInt();
}
sort(num);
}
//SORTING
public static void sort (int[] num){
boolean swapped = true;
while(swapped){
swapped = false;
for(int i=0;i<num.length-1;i++){
if(num[i]>num[i+1]){
int temp = num[i];
num[i] = num[i+1];
num[i+1] = temp;
swapped = true;
}
}
}
System.out.println("Sorted Result : "+Arrays.toString(num));
}
}
```

Note it can still be slightly improved: each time around the loop the largest number will end up as far as it can get towards the end of of the array: there's no need to check or swap till the end each time. By using a variable as the upper limit of the index "i" and decreasing its value after the for loop you can reduce the total number of iterations.

```
int end = num.length-1;
while(swapped){
swapped = false;
for(int i=0;i<end;i++){
if(num[i]>num[i+1]){
int temp = num[i];
num[i] = num[i+1];
num[i+1] = temp;
swapped = true;
}
}
end--;
}
```

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