How to remove duplicate elements in an array??in java

Question

{1,2,7,5,1,2,5,7}

and explain me plz

Answer 1

Use a set instead or convert the array into a set:

import java.util.Arrays;
import java.util.HashSet;
import java.util.Set;
import java.util.stream.Collectors;

public class Program
{
public static void main(String[] args) {
// If using the class wrapper Integer for array
// Integer[] x = {1,2,7,5,1,2,5,7};
// Set<Integer> y = new HashSet<Integer>(Arrays.asList(x));

// If using an int array
int[] x = {1,2,7,5,1,2,5,7};
Set<Integer> y = new HashSet<Integer>(Arrays.stream(x).boxed().collect(Collectors.toList()));

for(Integer i: y) {
System.out.print(i + " ");
}
}
}

Answer 2

You can also create a set of Integers like:

Set<Integer> set = new HashSet<>(Arrays.asList(1,2,7,5,1,2,5,7));

OR:

// Create an empty set
Set<Integer> set = new HashSet<>();
set.add(1);
set.add(2);
set.add(7);
set.add(5);
set.add(1); // duplicate not added
set.add(2); // duplicate not added
set.add(5); // duplicate not added
set.add(7); // duplicate not added

Answer 3

A set is a generic Collection Interface that will not contain duplicate elements. If an element that exists in the set is added to the set again that new element is discarded. When you create a set from a List it will go through each element of the List and add each non existing element to the set ignoring any duplicate elements. Since Set is a generic it will only accept something that derives from Object, so primitive types such as int, float, byte, double, boolean, etc are not allowed and instead require boxing in their class wrappers. Integer in the case of int.

This:
Integer[] x = {1,2,7,5,1,2,5,7};
Is equivalent to:
int[] x = {1,2,7,5,1,2,5,7};
but each int is boxed in the Integer wrapper.
Look into boxing, unboxing, and auto-boxing for more information.

Here we create a List of type Integer from the Integer array (not int array)
Arrays.asList(x)

In this version, we create a List of type Integer from the int array (not Integer array) by first boxing each int into an Integer object.
Arrays.stream(x).boxed().collect(Collectors.toList()) // Java 8

We then create a HashSet from the new Integer List
Set<Integer> y = new HashSet<Integer>();
Look more into polymorphism, generics, and java collections.

y is an unordered set containing only 1 of each Integer.

Then we loop over each element within the HashSet y using a for each type loop:

for(Integer i: y) {
System.out.print(i + " ");
}

outputting each Integer in the Set.

Answer 4

explain me this program plz

Answer 5

I didn't understand this