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 :

Return Type	Method	Description
static int	bitCount()	It returns the number of 1-bits in the 2's complement binary representation of the specified int value.
byte	byteValue()	It converts the given number into a primitive byte type and returns the value of integer object as byte.
Static int	compare()	It compares two int values numerically and returns the result in integer equivalent.
Int	compareTo()	It compares two integer objects numerically and returns the result as -1, 0 or 1.
static int	compareUnsigned()	It compares two integer objects numerically treating the values as unsigned and returns the result as -1, 0 or 1.
static Integer	decode()	It decodes a String object into an Integer value.
static int	divideUnsigned()	It returns the unsigned quotient of dividing the first argument by the second argument where each argument and the result is interpreted as an unsigned value.
double	doubleValue()	It converts the given Integer value and returns the result as a double equivalent.
boolean	equals()	It compares the value of the parameter to the value of the current Integer object and returns boolean ( True or False ).
float	floatValue()	It converts the given Integer value and returns the result as a float equivalent.
Static Integer	getInteger()	It determines the integer value of the system property with the specified name.
static int	hashCode()	It returns a hash code for the given Integer.
static int	highestOneBit()	It returns int value with at most a single one-bit, in the position of the highest-order leftmost one-bit in the specified int value.
static int	lowestOneBit()	It eturns int value with at most a single one-bit, in the position of the lowest-order rightmost one-bit in the specified int value.
static int	max()	It returns the maximum value amongst the two method argument.
static int	min()	It returns the minimum value amongst the two method argument.
int	intValue()	It returns the value of the specified number as an int.
long	longValue()	It returns the value of the specified long object as long equivalent.

static int	numberOfLeadingZeros()	It returns the total number of zero bits preceding the highest-order leftmost one-bit in the 2's complement binary representation of the specified int value.
static int	numberOfTrailingZeros()	It returns the total number of zero bits following the lowest-order rightmost one-bit in the 2's complement binary representation of the specified int value.
static int	parseInt()	It parses the String argument as a signed decimal Integer object.
static int	parseUnsignedInt()	It parses the String argument as an unsigned decimal Integer object.
static int	remainderUnsigned()	It returns the unsigned remainder from dividing the first argument by the second argument where each argument and the result is interpreted as an unsigned value.
static int	reverse()	It returns the value obtained by reversing the order of the bits in the 2's complement binary representation of the specified int value.
static int	reverseBytes()	It returns the value obtained by reversing the order of the bytes in the 2's complement binary representation of the specified int value.
static int	rotateLeft()	It returns the value obtained by rotating the 2's complement binary representation of the specified int value left by the specified number of bits.
static int	rotateRight()	It returns the value obtained by rotating the 2's complement binary representation of the specified int value right by the specified number of bits.
short	shortValue()	It returns the value of this Integer as a short type after a primitive conversion.
static int	signum()	It returns the signum function of the specified int value.
static int	sum()	It returns the sum by adding two integers together as per the + operator.
static String	toBinaryString()	It returns a string representation of the integer argument as an unsigned integer in binary base 2.
static String	toHexString()	It returns a string representation of the integer argument as an unsigned integer in binary base 16.
static String	toOctalString()	It returns a string representation of the integer argument as an unsigned integer in binary base 8.
String	toString()	It returns a String object representing the value of the Number Object.
static String	toUnsignedString()	It converts the argument to a long by an unsigned conversion.
static long	toUnsignedLong()	It returns a string representation of the argument as an unsigned decimal value.
static Integer	valueOf()	It returns the relevant Integer Object holding the value of the argument passed.

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"));
  }
}