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TreeSet equals() method in Java with Example
  • Last Updated : 27 Dec, 2018

The equals() method of java.util.TreeSet class is used to compare the specified object with this set for equality. Returns true if and only if the specified object is also a set, both sets have the same size, and all corresponding pairs of elements in the two sets are equal. (Two elements e1 and e2 are equal if (e1==null ? e2==null : e1.equals(e2)).) In other words, two sets are defined to be equal if they contain the same elements in the same order.

Syntax:

public boolean equals(Object o)

Parameters: This method takes the object o as a parameter to be compared for equality with this set.

Returns Value: This method returns true if the specified object is equal to this set.

Below are the examples to illustrate the equals() method.



Example 1:




// Java program to demonstrate equals()
// method of TreeSet
  
import java.util.*;
  
public class GFG {
    public static void main(String[] argv)
    {
  
        // Creating object of TreeSet<String>
        TreeSet<String>
            set1 = new TreeSet<String>();
  
        // Populating set1
        set1.add("A");
        set1.add("B");
        set1.add("C");
        set1.add("D");
        set1.add("E");
  
        // print set1
        System.out.println("First TreeSet: "
                           + set1);
  
        // Creating another object of TreeSet<String>
        TreeSet<String>
            set2 = new TreeSet<String>();
  
        // Populating set2
        set2.add("A");
        set2.add("B");
        set2.add("C");
        set2.add("D");
        set2.add("E");
  
        // print set2
        System.out.println("Second TreeSet: "
                           + set2);
  
        // comparing first TreeSet to another
        // using equals() method
        boolean value
            = set1.equals(set2);
  
        // print the value
        System.out.println("Are both set equal: "
                           + value);
    }
}
Output:
First TreeSet: [A, B, C, D, E]
Second TreeSet: [A, B, C, D, E]
Are both set equal: true

Example 2:




// Java program to demonstrate equals()
// method of TreeSet
  
import java.util.*;
  
public class GFG1 {
    public static void main(String[] argv)
    {
  
        // Creating object of TreeSet
        TreeSet<Integer>
            set1 = new TreeSet<Integer>();
  
        // Populating set1
        set1.add(10);
        set1.add(20);
        set1.add(30);
        set1.add(40);
        set1.add(50);
  
        // print set1
        System.out.println("First TreeSet: "
                           + set1);
  
        // Creating another object of TreeSet
        TreeSet<Integer>
            set2 = new TreeSet<Integer>();
  
        // Populating set2
        set2.add(10);
        set2.add(20);
        set2.add(30);
  
        // print set2
        System.out.println("Second TreeSet: "
                           + set2);
  
        // comparing first TreeSet to another
        // using equals() method
        boolean value = set1.equals(set2);
  
        // print the value
        System.out.println("Are both set equal: "
                           + value);
    }
}
Output:
First TreeSet: [10, 20, 30, 40, 50]
Second TreeSet: [10, 20, 30]
Are both set equal: false

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