Int to Integer in Java

Int to Integer in Java | In this blog, we are converting the primitive data type int to the Integer object. The int is the primitive data type whereas the Integer is a wrapper class. The wrapper class is the way to use the primitive data types in Java as objects. So here we are basically converting the data type to an object. Also see:- Int vs Integer Java, Convert Integer to int in Java

Following are the different ways to convert int to Integer in Java programming language:-

  1. AutoBoxing
  2. valueOf(-) Method
  3. Integer class Constructor

Convert Int To Integer in Java using AutoBoxing

When we assign an int primitive value to an Integer type variable then due to the autoboxing feature, Java internally converts primitive int to an Integer object. Hence to convert int to integer in Java using autoboxing we have to just assign the int value to the Integer object. The below program demonstrates it.

public class Main {
    public static void main(String[] args) {
        int num = 10;
        Integer num1 = num; // autoboxing
        
        System.out.println(num1);
        System.out.println(num1.getClass().getName());
        System.out.println(num1.doubleValue());
    }
}

Output:-

10
java.lang.Integer
10.0

We can also directly assign value to an Integer object without creating an int-type variable. Let us see it through an example:-

public class Main {
    public static void main(String[] args) {
        Integer num1 = 99; // autoboxing

        System.out.println(num1);
        System.out.println(num1.getClass().getName());
        System.out.println(num1.doubleValue());
    }
}

Output:-

99
java.lang.Integer
99.0

Convert Int To Integer Java using valueOf() Method

Integer class contains the valueOf() method to create an Integer object from an int type value. Following is the prototype of the valueOf() method:- public static Integer valueOf(int i)

The valueOf() method is a static method. Integer class belongs to java.lang package which is the default package available to every Java program therefore we don’t need to import the Integer class explicitly.

public class Main {
    public static void main(String[] args) {
        int num = 50;
        Integer num1 = Integer.valueOf(num);
        // Integer num1 = Integer.valueOf(50);

        System.out.println(num1);
        System.out.println(num1.getClass().getName());
        System.out.println(num1.doubleValue());
    }
}

Output:-

50
java.lang.Integer
50.0

Convert Int To Integer Java using Constructor

We can also take the help of the constructor of Java Integer class to convert int to Integer object. However, the constructors of all wrapper classes including the Integer class are deprecated and can be removed in the upcoming version. Therefore it is not recommended to use the constructors of any wrapper class. Instead, we should use the valueOf() method of those wrapper classes to convert primitive to wrapper class Object.

public class Main {
    public static void main(String[] args) {
        int num = 50;

        // not recommended
        Integer num1 = new Integer(num);
        // Integer num1 = new Integer(50);

        System.out.println(num1);
        System.out.println(num1.getClass().getName());
    }
}

Output:-

50
java.lang.Integer

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