Java Vector contains() Method (original) (raw)

Last Updated : 16 Jan, 2025

The **contains() method in Java is used to check whether a specific element is present in the Vector or not.

**Example 1: In this example, we will **check whether a particular string is present in the vector or not.

Java `

// Java program to demonstrate the use // of the contains() method with Strings import java.util.Vector;

public class Geeks { public static void main(String[] args) {

    // Create a vector to store strings
    Vector<String> v = new Vector<>();

    // Add elements to the vector
    v.add("Welcome");
    v.add("To");
    v.add("Geeks");
    v.add("4");
    v.add("Geeks");

    // Display the contents of the vector
    System.out.println("Vector: " + v);

    // Check if the vector contains "Geeks"
    System.out.println("Contains 'Geeks'? " 
                       + v.contains("Geeks")); 

    // Check if the vector contains "4"
    System.out.println("Contains '4'? " 
                       + v.contains("4"));         

    // Check if the vector contains "No"
    System.out.println("Contains 'No'? " 
                       + v.contains("No"));      
}

}

Output

Vector: [Welcome, To, Geeks, 4, Geeks] Contains 'Geeks'? true Contains '4'? true Contains 'No'? false

**Syntax of Vector contains() Method

boolean contains(Object obj)

**Parameters: obj: The element to be checked for its presence in vector.

**Return Type:

It returns true, if the element is present in the vector
It returns false, if the element is not present in the vector

**Example 2: In this example, we will **check whether a particular integer element is present in the vector or not.

Java `

// Java program to demonstrate the use // of the contains() method with Integers import java.util.Vector;

public class Geeks { public static void main(String[] args) {

    // Create a vector to store integers
    Vector<Integer> v = new Vector<>();

    // Add elements to the vector
    v.add(10);
    v.add(15);
    v.add(30);
    v.add(20);
    v.add(5);

    // Display the contents of the vector
    System.out.println("Vector: " + v);

    // Check if the vector contains 100
    System.out.println("Contains 100? " 
                       + v.contains(100)); 

    // Check if the vector contains 30
    System.out.println("Contains 30? " 
                       + v.contains(30));   
}

}

Output

Vector: [10, 15, 30, 20, 5] Contains 100? false Contains 30? true

**Example 3: The below Java program demonstrates **how the contains() method works with custom objects by overriding the equals() method.

Java `

// Java program to demonstrate the // contains() method with custom objects import java.util.Vector;

class Person { String name; int age;

// Constructor to initialize Person objects
Person(String name, int age) {
    this.name = name;
    this.age = age;
}

// Overriding equals() to compare custom objects
@Override
public boolean equals(Object obj) {
  
     // Check if the same object is compared
    if (this == obj) 
      return true;
    if (obj == null || getClass() != obj.getClass())
      
      // Check for null or different types
      return false; 
    Person person = (Person) obj;
    return age == person.age && name.equals(person.name); 
}

// Overriding toString() for 
// better output readability
@Override
public String toString() {
    return "Person{name='" + name + "', age=" + age + "}";
}

}

public class Main { public static void main(String[] args) {

    // Create a vector to store custom Person objects
    Vector<Person> v = new Vector<>();

    // Add Person objects to the vector
    v.add(new Person("Geek1", 25));
    v.add(new Person("Geek2", 30));
    v.add(new Person("Geek3", 35));

    // Display the contents of the vector
    System.out.println("Vector: " + v);

    // Check if the vector contains 
    // a specific Person object
    System.out.println("Contains Geek1? " + 
                       v.contains(new Person("Geek1", 25))); 

    // Check if the vector contains 
    // another specific Person object
    System.out.println("Contains Geek5? " 
                       + v.contains(new Person("Geek5", 40))); 
}

}

Output

Vector: [Person{name='Geek1', age=25}, Person{name='Geek2', age=30}, Person{name='Geek3', age=35}] Contains Geek1? true Contains Geek5? false