Java program converts primitive types and wrapper objects

Comprehensive Java Examples

In this tutorial, we will learn how to convert primitive data types to corresponding wrapper objects in Java, and vice versa.

Example1: Java program to convert primitive types to wrapper objects

class Main {
　　public static void main(String[] args) {
　　　　//create primitive type
　　　　int var1　=　5;
　　　　double var2　=　5.65;
　　　　boolean var3　= true;
　　　　//convert to wrapper object
　　　　Integer obj1　= Integer.valueOf(var1);
　　　　Double obj2　= Double.valueOf(var2);
　　　　Boolean obj3　= Boolean.valueOf(var3);
　　　　//check if obj is an object
　　　　//corresponding wrapper class
　　　　if(obj1　instanceof Integer) {
　　　　　　System.out.println("Create an Integer object.");
　　　　}
　　　　if(obj2　instanceof Double) {
　　　　　　System.out.println("Create a Double object.");
　　　　}
　　　　if(obj3　instanceof Boolean) {
　　　　　　System.out.println("Create a Boolean object.");
　　　　}
　　}
}

Output Result

Create an Integer object.
Create a Double object.
Create a Boolean object.

In the above example, we created variables of primitive types (int, double, and boolean). Here, we used the valueOf() method of the Wrapper class (Integer, Double, and Boolean) to convert primitive types to objects.

To understand wrapper classes in Java, please visitJava Wrapper Classes.

Example2: Java program to convert wrapper objects to primitive types

class Main {
　　public static void main(String[] args) {
　　　　//create wrapper class objects
　　　　Integer obj1　= Integer.valueOf(23);
　　　　Double obj2　= Double.valueOf(5.55);
　　　　Boolean obj3　= Boolean.valueOf(true);
　　　　//convert to primitive type
　　　　int var1　=  obj1.intValue();
　　　　double var2　=  obj2.doubleValue();
　　　　boolean var3　=  obj3.booleanValue();
　　　　//Print Original Values
　　　　System.out.println("Int variable value:  ")　+　var1);
　　　　System.out.println("Double variable value:  ")　+　var2);
　　　　System.out.println("Boolean variable value:  ")　+　var3);
　　}
}

Output Result

Int variable value:　23
Double variable value:　5.55
Boolean variable value:  true

In the above example, we have created objects of wrapper classes (Integer, Double, and Boolean).

Then, we use the intValue(), doubleValue(), and booleanValue() methods respectively to change the object to the corresponding primitive type (int, double, and boolean).

Note: The Java compiler automatically converts primitive types to their corresponding objects and vice versa. This process is calledAuto-boxing and Unboxing.For more information, please visitJava Auto-boxing and Unboxing.

Comprehensive Java Examples