java lang Integer Class | Integer class methods in Java

java.lang.Integer Class

Integer Class in Java

The Integer class wraps the value of primitive data type int into Integer object. An object of type Integer contains a single field whose type is int. In other words the wrapper classes create objects for primitive data types. The wrapper classes are Boolean, Byte, Character, Short, Integer, Float, Long and Double.

Java Integer Methods or Integer class methods in Java

Java Integer class or Java wrapper class Integer provides several useful methods for converting a int to a String and a String to a int, as well as other constants and methods dealing with int. The various Java Integer methods are as follows :

java.lang.Integer Class Example

/*  Java Integer Class Example
    Save with file name IntegerExample.java  */
public class IntegerExample
{
	public static void main(String args[])
	{
		// JAVA INTEGER DECLARATION
		Integer b;
		// MEMORY ALLOCATION FOR JAVA INTEGER
		b = new Integer(101);
		// JAVA INTEGER CLASS OUTPUT
		System.out.println("Java Integer Class Example");
		// RETURNS byte PRIMITIVE DATA TYPE
		System.out.println("byte Value is : "+ b.byteValue());
		// RETURNS short PRIMITIVE DATA TYPE
		System.out.println("short Value is : "+ b.shortValue());
		// RETURNS double PRIMITIVE DATA TYPE
		System.out.println("double Value is : "+ b.doubleValue());
		// RETURNS float PRIMITIVE DATA TYPE
		System.out.println("float Value is : "+ b.floatValue());
		// RETURNS int PRIMITIVE DATA TYPE
		System.out.println("int Value is : "+ b.intValue());
		// RETURNS long PRIMITIVE DATA TYPE
		System.out.println("long Value is : "+ b.longValue());
	}
}

java.lang.Integer Class Example 2

/*	Java Integer Class Example 2
		Save with file name IntegerExample2.java	*/
public class IntegerExample2
{
	public static void main(String args[])
	{
		// JAVA INTEGER DECLARATION
		Integer b, b2;
		// MEMORY ALLOCATION FOR JAVA INTEGER
		b = new Integer(101);
		b2 = new Integer("102");
		// JAVA INTEGER CLASS OUTPUT
		System.out.println("Java Integer Class Example 2");
		System.out.println("b Value is : "+ b.intValue());
		System.out.println("b2 Value is : "+ b2.intValue());
		System.out.println("b compareTo b2 : "+ b.compareTo(b2));
		System.out.println("b equals b2 : "+ b.equals(b2));
	}
}

Following Java Integer class example you can learn how to use static methods of Java Integer Class. If you use static methods you need not to create the class instance. You can call static methods using the class name as reference.

java.lang.Integer Class Example 3

/*	Java Integer Class Example 3
		Save with file name IntegerExample3.java	*/
public class IntegerExample3
{
	public static void main(String args[])
	{
		// INTEGER CLASS STATIC METHODS USAGE
		System.out.println("Java Integer Class Example 3");
		// RETURN Java Integer OBJECT WITH THE SPECIFIED PRIMITIVE int DATA TYPE
		System.out.println("valueOf : "+ Integer.valueOf(101));
		// RETURN Integer OBJECT WITH THE SPECIFIED
		// PRIMITIVE int DATA TYPE AS String
		System.out.println("valueOf : "+ Integer.valueOf("103"));
		// RETURN PRIMITIVE int DATA TYPE WITH THE SPECIFIED
		// PRIMITIVE int DATA TYPE AS String
		System.out.println("parseInt : "+ Integer.parseInt("105"));
	}
}