How to Remove Duplicates in a Vector in Java - Step by Step Examples

How to Remove Duplicates in a Vector in Java ?

Answer

To remove duplicates from a Vector in Java, you can use a LinkedHashSet to maintain the order of elements or the Collections.sort and Collections.frequency methods to remove duplicates.

✐ Examples

1 Remove Duplicates Using LinkedHashSet

In this example,

We start by importing the necessary classes: java.util.Vector, java.util.LinkedHashSet, and java.util.Set.
We create a Vector named vector and initialize it with some integer values, including duplicates.
Next, we create a LinkedHashSet named set and initialize it with the elements of vector. The LinkedHashSet maintains the insertion order and automatically removes duplicates.
We then clear the original vector and add all elements from the set back to the vector.
Finally, we print the modified vector to standard output to see the result.

Java Program

import java.util.Vector;
import java.util.LinkedHashSet;
import java.util.Set;

public class Main {
    public static void main(String[] args) {
        Vector&lt;Integer&gt; vector = new Vector&lt;&gt;();
        vector.add(1);
        vector.add(2);
        vector.add(2);
        vector.add(3);
        vector.add(4);
        vector.add(4);
        vector.add(4);
        vector.add(5);
        vector.add(6);
        vector.add(6);
        
        Set&lt;Integer&gt; set = new LinkedHashSet&lt;&gt;(vector);
        vector.clear();
        vector.addAll(set);
        
        System.out.println("Vector after removing duplicates: " + vector);
    }
}

Output

Vector after removing duplicates: [1, 2, 3, 4, 5, 6]

2 Remove Consecutive Duplicates from a Sorted Vector

In this example,

We start by importing the necessary classes: java.util.Vector and java.util.Collections.
We create a Vector named vector and initialize it with some integer values, including duplicates.
Next, we use the Collections.sort method to sort the vector. This step is crucial because removing consecutive duplicates requires the vector to be sorted.
We then iterate over the sorted vector and remove consecutive duplicate elements manually by checking if the current element is equal to the previous element.
Finally, we print the modified vector to standard output to see the result.

Java Program

import java.util.Vector;
import java.util.Collections;

public class Main {
    public static void main(String[] args) {
        Vector&lt;Integer&gt; vector = new Vector&lt;&gt;();
        vector.add(1);
        vector.add(2);
        vector.add(2);
        vector.add(3);
        vector.add(4);
        vector.add(4);
        vector.add(4);
        vector.add(5);
        vector.add(6);
        vector.add(6);
        
        Collections.sort(vector);
        
        Vector&lt;Integer&gt; uniqueVector = new Vector&lt;&gt;();
        for (int i = 0; i &lt; vector.size(); i++) {
            if (i == 0 || !vector.get(i).equals(vector.get(i - 1))) {
                uniqueVector.add(vector.get(i));
            }
        }
        
        System.out.println("Vector after removing consecutive duplicates: " + uniqueVector);
    }
}

Output

Vector after removing consecutive duplicates: [1, 2, 3, 4, 5, 6]

Summary

In this tutorial, we learned How to Remove Duplicates in a Vector in Java language with well detailed examples.

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