Método LinkedHashSet contains() en Java con ejemplos

En Java, la clase LinkedHashSet contiene métodos conocidos como contains() que se utilizan para devolver verdadero si este conjunto contiene el elemento especificado, de lo contrario, es falso.

Sintaxis: 

public boolean contains(Object o)

Parámetros: Elemento o como parámetro cuya presencia en este conjunto se quiere probar.

Tipo de retorno: un valor booleano, verdadero si este conjunto contiene el elemento especificado.

Ejemplo 1:

// Java program to Illustrate contains() Method
// of LinkedHashSet class
// For String value
 
// Importing required classes
import java.util.*;
 
// Main class
public class GFG {
 
    // Main driver method
    public static void main(String[] argv) throws Exception
    {
 
        // Try block to check for exceptions
        try {
 
            // Creating an empty LinkedHashSet
            // Declaring object of string type
            LinkedHashSet<String> linkset
                = new LinkedHashSet<String>();
 
            // Populating above HashSet
            linkset.add("A");
            linkset.add("B");
            linkset.add("C");
 
            // Printing all elements of above LinkedHashSet
            System.out.println("LinkedHashSet: " + linkset);
 
            // Checking the existence of element
            // using contains() method
            boolean exist = linkset.contains("C");
 
            // Printing boolean value if present or not
            System.out.println("Is the element"
                               + " 'C' present: " + exist);
        }
 
        // Catch block to check for exceptions
        catch (NullPointerException e) {
 
            // Display message if exception occurs
            System.out.println("Exception thrown : " + e);
        }
    }
}

LinkedHashSet: [A, B, C]
Is the element 'C' present: true

Ejemplo 2:

// Java program to Illustrate contains() Method
// of LinkedHashSet class
// For Integer value
 
// Importing required classes
import java.util.*;
 
// Main class
public class GFG {
 
    // Main driver method
    public static void main(String[] argv) throws Exception
    {
 
        // Try block to check for exceptions
        try {
 
            // Creating an empty LinkedHashSet
            // Declaring object of integer type
            LinkedHashSet<Integer> linkset
                = new LinkedHashSet<Integer>();
 
            // Populating above HashSet
            linkset.add(10);
            linkset.add(20);
            linkset.add(30);
 
            // Printing all elements of above LinkedHashSet
            System.out.println("LinkedHashSet: " + linkset);
 
            // Checking the existence of element
            // using contains() method
            boolean exist = linkset.contains(25);
 
            // Printing boolean value if present or not
            System.out.println("Is the element"
                               + " '25' present: " + exist);
        }
 
        // Catch block to check for exceptions
        catch (NullPointerException e) {
 
            // Display message if exception occurs
            System.out.println("Exception thrown : " + e);
        }
    }
}

LinkedHashSet: [10, 20, 30]
Is the element '25' present: false