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
