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Java Program to Remove duplicate elements from ArrayList
In this article, we will understand how to remove duplicate elements from arrayList. The ArrayList class is a resizable array, which can be found in the java.util package. The difference between a built-in array and an ArrayList in Java, is that the size of an array cannot be modified.
Below is a demonstration of the same −
Suppose our input is −
Input list : [150, 250, 300, 250, 500, 150, 600, 750, 300]
The desired output would be −
The list with no duplicates is: [150, 250, 300, 500, 600, 750]
Algorithm
Step 1 - START Step 2 - Declare namely Step 3 - Define the values. Step 4 – Create an ArrayList of integer values and initialize elements in it. Step 5 - Display the ArrayList on the console. Step 6 - Create another linkedhashset of integers. Step 7 - Use the ‘addAll’ method to include elements from previous ArrayList into it as elements. Step 8 - Since it is a set, it only adds the unique values. Step 9 - Clear the elements of the ArrayList. Step 10- Display the set on the console with unique elements. Step 11- Stop
Example 1
Here, we bind all the operations together under the ‘main’ function.
import java.util.ArrayList;
import java.util.Arrays;
import java.util.LinkedHashSet;
import java.util.Set;
public class Demo {
public static void main(String[] args) {
System.out.println("The required packages have been imported");
ArrayList<Integer> input_list = new ArrayList<>(Arrays.asList(150, 250, 300, 250, 500, 150, 600, 750, 300));
System.out.println("The list is defined as: " + input_list);
Set<Integer> temp_set = new LinkedHashSet<>();
temp_set.addAll(input_list);
input_list.clear();
input_list.addAll(temp_set);
System.out.println("\nThe list with no duplicates is: \n" + input_list);
}
}Output
The required packages have been imported The list is defined as: [150, 250, 300, 250, 500, 150, 600, 750, 300] The list with no duplicates is: [150, 250, 300, 500, 600, 750]
Example 2
Here, we encapsulate the operations into functions exhibiting object oriented programming.
import java.util.ArrayList;
import java.util.Arrays;
import java.util.LinkedHashSet;
import java.util.Set;
public class Demo {
static void remove_duplicates(ArrayList<Integer> input_list){
Set<Integer> temp_set = new LinkedHashSet<>();
temp_set.addAll(input_list);
input_list.clear();
input_list.addAll(temp_set);
System.out.println("\nThe list with no duplicates is: \n" + input_list);
}
public static void main(String[] args) {
System.out.println("The required packages have been imported");
ArrayList<Integer> input_list = new ArrayList<>(Arrays.asList(150, 250, 300, 250, 500, 150, 600, 750, 300));
System.out.println("The list is defined as: " + input_list);
remove_duplicates(input_list);
}
}Output
The required packages have been imported The list is defined as: [150, 250, 300, 250, 500, 150, 600, 750, 300] The list with no duplicates is: [150, 250, 300, 500, 600, 750]
Updated on: 30-Mar-2022
2K+ Views
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