Removing Duplicate elements from array is not difficult, just we have to concentrate on array index. We can remove duplicate elements from array in 2 way: using temporary array or using seperate index. For removing duplicate elements array must be sorted. You can use array.sort() in-built function or seperate programs like Selection Sort or Bubble Sort .

Java Program - Remove Duplicate Elements using Temporary Array

``````public class RemoveDuplicate1{

public static int RemoveDuplicate(int arr[],int n){

int j=0;

int temp[] = new int [n];

if(n==0 || n==1){
return n;
}

for(int i=0; i<n-1;i++){
if(arr[i]!=arr[i+1]){
temp[j++] = arr[i];
}
}

temp[j++] = arr[n-1];

for(int i=0; i<j;i++){
arr[i] = temp[i];
}

return j;

}

public static void main(String []args){

int arr[] = {10, 20, 20, 30, 30, 60, 60, 70, 70};

int length = arr.length;

System.out.println("Without Removing Duplicate");

for(int i: arr){
System.out.print(i+"  ");
}

length = RemoveDuplicate(arr, length);

System.out.println("\nAfter Removing Duplicate");

for(int i=0; i<length;i++){
System.out.print(arr[i]+"  ");
}

}
}

``````

Java Program - Remove Duplicate Elements Using Separate Index
``````
public class RemoveDuplicate2{

public static int RemoveDuplicateIndex(int arr[],int n){

int j=0;

if(n==0 || n==1){
return n;
}

for(int i=0;i<n-1;i++){
if(arr[i]!=arr[i+1]){
arr[j++]=arr[i];
}
}

arr[j++]=arr[n-1];

return j;

}

public static void main(String []args){

int arr[] = {10, 20, 20, 30, 30, 60, 60, 70, 70, 90};

int length = arr.length;

System.out.println("Without Removing Duplicate");

for(int i: arr){
System.out.print(i+"  ");
}

length = RemoveDuplicateIndex(arr, length);

System.out.println("\nAfter Removing Duplicate");

for(int i=0; i<length;i++){
System.out.print(arr[i]+"  ");
}

}
}

``````