How to implement selection sort algorithm in java

In this post we will see how to implement the selection sort algorithm in java with a sample program.In selection sorting

1. We will find the smallest element in the array  and  then swap this element with the  element in the 0th index of the  array.
2. Then we will find the second smallest element in the array and  swap this element with the element in the 1st index of the array.This iteration will continue upto the number of times equal to the the size of the array.

Below sample program will explain this in detail.

package test;

public class SelectionSortSample {

public static void main(String[] args) {
// TODO Auto-generated method stub
int[] arry = new int[] { 20, 3, 150, 5, 6, 78, 2, 123, 43, 45, 99, 1,
12 };
SelectionSortSample selectionSort = new SelectionSortSample();
selectionSort.sort(arry);
}

public void sort(int[] arry) {
printElements(arry);
int len = arry.length;
int min = 0;
int temp=0;
for (int i = 0; i < len; i++) {
min=i;
for(int j=i+1;j<len;j++)
{
if(arry[j]<arry[min])
{
min=j;
}
}
temp=arry[i];
arry[i]=arry[min];
arry[min]=temp;
printElements(arry);
}

}

public void printElements(int[] arry) {
for (int i = 0; i < arry.length; i++) {
System.out.print("  " + arry[i]);
}
System.out.println();
}

}

When we run the above program,we will get this output

  20  3  150  5  6  78  2  123  43  45  99  1  12
  1  3  150  5  6  78  2  123  43  45  99  20  12
  1  2  150  5  6  78  3  123  43  45  99  20  12
  1  2  3  5  6  78  150  123  43  45  99  20  12
  1  2  3  5  6  78  150  123  43  45  99  20  12
  1  2  3  5  6  78  150  123  43  45  99  20  12
  1  2  3  5  6  12  150  123  43  45  99  20  78
  1  2  3  5  6  12  20  123  43  45  99  150  78
  1  2  3  5  6  12  20  43  123  45  99  150  78
  1  2  3  5  6  12  20  43  45  123  99  150  78
  1  2  3  5  6  12  20  43  45  78  99  150  123
  1  2  3  5  6  12  20  43  45  78  99  150  123
  1  2  3  5  6  12  20  43  45  78  99  123  150
  1  2  3  5  6  12  20  43  45  78  99  123  150

Above output will show the array elements position at the end of each iteration.

How to implement insertion sort algorithm in java

In this post we will see how to implement the insertion sort algorithm in java with a sample program.In insertion sorting

1. we will select a key from the array for each iteration ,which will start from index 1 of the array to the last element.
2. The key will be compared with the elements precedence to it (i.e if the key selected is at index 2,it will be compared with the elements at index 1 and index 0) and the key will be inserted at the right position in the array.

Below sample program will explain this in detail.

package test;

public class InsertionSortSample {

public static void main(String[] args) {
int[] arry = new int[] { 20, 3, 150, 5, 6, 78, 2, 123, 43, 45, 99, 1,
12 };
InsertionSortSample insertionSort = new InsertionSortSample();
insertionSort.sort(arry);
}

public void sort(int[] arry) {
printElements(arry);
int len = arry.length;
int key = 0;
int j=0;
for (int i = 1; i < len; i++) {
key=arry[i];
j=i-1;
while(j>=0 && key<arry[j])
{
arry[j+1]=arry[j];
j--;
}
arry[j+1]=key;
printElements(arry);
}

}

public void printElements(int[] arry) {
for (int i = 0; i < arry.length; i++) {
System.out.print("  " + arry[i]);
}
System.out.println();
}

}

When we run the above program,we will ge this output

  20  3  150  5  6  78  2  123  43  45  99  1  12
  3  20  150  5  6  78  2  123  43  45  99  1  12
  3  20  150  5  6  78  2  123  43  45  99  1  12
  3  5  20  150  6  78  2  123  43  45  99  1  12
  3  5  6  20  150  78  2  123  43  45  99  1  12
  3  5  6  20  78  150  2  123  43  45  99  1  12
  2  3  5  6  20  78  150  123  43  45  99  1  12
  2  3  5  6  20  78  123  150  43  45  99  1  12
  2  3  5  6  20  43  78  123  150  45  99  1  12
  2  3  5  6  20  43  45  78  123  150  99  1  12
  2  3  5  6  20  43  45  78  99  123  150  1  12
  1  2  3  5  6  20  43  45  78  99  123  150  12
  1  2  3  5  6  12  20  43  45  78  99  123  150

Above output will show the array elements position at the end of each iteration and how the key is inserted at the right position.