- Java.util Package Classes
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- Java.util Package Extras
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- Java.util Useful Resources
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- Java.util - Discussion
Java Vector contains() Method
Description
The Java Vector contains(Object elem) method is used to test the existence of an element in a vector.
Declaration
Following is the declaration for java.util.Vector.contains() method
public boolean contains(Object elem)
Parameters
elem − This is an object as input.
Return Value
true − It returns true if and only if the specified object is the same as a component in this vector.Otherwise it returns false.
Exception
ClassCastException − if the type of the specified element is incompatible with this collection (optional).
NullPointerException − if the specified element is null and this collection does not support null elements (optional).
Checking an Element's Presence in a Vector of Integer Example
The following example shows the usage of Java Vector contains() method. We're using Integers. We'll be adding few elements and then checking if certain element is present or not.
package com.tutorialspoint; import java.util.Vector; public class VectorDemo { public static void main(String[] args) { // create an empty vector Vector<Integer> vector = new Vector<>(); // use add() method to add elements in the vector vector.add(20); vector.add(30); vector.add(10); vector.add(18); // let us print all the elements available in vector System.out.println("Vector = " + vector); // vector contains element 10 if (vector.contains(10)) { System.out.println("element 10 is present in the vector"); } else { System.out.println("element 10 is not present in the vector"); } // vector does not contain element 25 if (vector.contains(25)) { System.out.println("element 25 is present in the vector"); } else { System.out.println("element 25 is not present in the vector"); } } }
Output
Let us compile and run the above program, this will produce the following result −
Vector = [20, 30, 10, 18] element 10 is present in the vector element 25 is not present in the vector
Checking an Element's Presence in a Vector of String Example
The following example shows the usage of Java Vector contains() method with Strings. We'll be adding few elements and then checking if certain element is present or not.
package com.tutorialspoint; import java.util.Vector; public class VectorDemo { public static void main(String[] args) { // create an empty vector Vector<String> vector = new Vector<>(); // use add() method to add elements in the vector vector.add("Welcome"); vector.add("to"); vector.add("tutorialspoint"); vector.add(".com"); // let us print all the elements available in vector System.out.println("Vector = " + vector); // vector contains element tutorialspoint if (vector.contains("tutorialspoint")) { System.out.println("element tutorialspoint is present in the vector"); } else { System.out.println("element tutorialspoint is not present in the vector"); } // vector does not contain element html if (vector.contains("html")) { System.out.println("element html is present in the vector"); } else { System.out.println("element html is not present in the vector"); } } }
Output
Let us compile and run the above program, this will produce the following result −
Vector = [Welcome, to, tutorialspoint, .com] element tutorialspoint is present in the vector element html is not present in the vector
Checking an Element's Presence in a Vector of Object Example
The following example shows the usage of Java Vector contains() method with Student objects. We'll be adding few elements and then checking if certain element is present or not.
package com.tutorialspoint; import java.util.Vector; public class VectorDemo { public static void main(String[] args) { // create an empty vector Vector<Student> vector = new Vector<>(); // use add() method to add elements in the vector vector.add(new Student(1, "Julie")); vector.add(new Student(2, "Robert")); vector.add(new Student(3, "Adam")); // let us print all the elements available in vector System.out.println("Vector = " + vector); // vector contains element Robert if (vector.contains(new Student(2, "Robert"))) { System.out.println("Student Robert is present in the vector"); } else { System.out.println("Student Robert is not present in the vector"); } // vector does not contain element Jane if (vector.contains(new Student(4, "Jane"))) { System.out.println("Student Jane is present in the vector"); } else { System.out.println("Student Jane is not present in the vector"); } } } class Student { int rollNo; String name; Student(int rollNo, String name){ this.rollNo = rollNo; this.name = name; } @Override public String toString() { return "[ " + this.rollNo + ", " + this.name + " ]"; } @Override public boolean equals(Object obj) { Student s = (Student)obj; return this.rollNo == s.rollNo && this.name.equalsIgnoreCase(s.name); } }
Output
Let us compile and run the above program, this will produce the following result −
Vector = [[ 1, Julie ], [ 2, Robert ], [ 3, Adam ]] Student Robert is present in the vector Student Jane is not present in the vector