Java int type

In this chapter you will learn:

Java int type introduction
What is octal integer and how to use it in Java
What is hexadecimal integer and how to use it in Java
Find out Max, min value of an integer type variable
How to create Integer using its constructors
How to compare two integer values
How to reverse and rotate the integer in binary format
How to bit oriented operation on int type value
How to get the sign of an Integer
How to get the leading and trailing zeros

int type

int is a signed 32-bit type that has a range from -2,147,483,648 to 2,147,483,647. When byte and short values are used in an expression they are promoted to int when the expression is evaluated.

Integer class is the wrapper class for int primitive type.

octal integer(base eight)

Octal values are denoted in Java by a leading zero. valid value 09 will produce an error from the compiler, since 9 is outside of octal's 0 to 7 range.

public class Main {
//from   j  a v  a 2  s.  c  o m
  public static void main(String[] args) {
    int i = 010;

    System.out.println(i);
  }
}

The output:

hexadecimal integer(base 16)

hexadecimal matches with modulo 8 word sizes, such as 8, 16, 32, and 64 bits. You signify a hexadecimal constant with a leading zero-x, (0x or 0X).

The range of a hexadecimal digit is 0 to 15, so A through F (or a through f ) are substituted for 10 through 15.

An integer literal can always be assigned to a long variable. An integer can also be assigned to a char as long as it is within range.

Max, min value of an integer type variable

static int MAX_VALUE stores the maximum value an int can have.
static int MIN_VALUE stores the minimum value an int can have.
static int SIZE stores the number of bits used to represent an int value.

public class Main {
  public static void main(String[] args) {
    System.out.println(Integer.MAX_VALUE);
    System.out.println(Integer.MIN_VALUE);
    System.out.println(Integer.SIZE);/*from   jav  a 2 s  . co  m*/
  }
}

The output:

Create Integer using its constructors

Integer(int value) creates an Integer object for the int value.
Integer(String s) creates an Integer object for the int value indicated by s.

public class Main {
  public static void main(String[] args) {
/*from ja v  a2s. c o m*/
    Integer integer1 = new Integer("1");
    Integer integer2 = new Integer("2");
    
    System.out.println(integer1);
    System.out.println(integer2);
  }
}

The output:

The following code creates Integer objects from int literal and string representation

public class Main {
  public static void main(String[] args) {
    Integer intObj1 = new Integer(10);
    Integer intObj2 = new Integer("10");
    System.out.println(intObj1);/* jav a  2 s  .c om*/
    System.out.println(intObj2);
  }
}

The output:

Compare two integer values

int compareTo(Integer anotherInteger) compares two Integer objects numerically.
boolean equals(Object obj) compares this object to the specified object.

The following table lists the return values from compareTo(Integer anotherInteger)

Value	Description
0	if this Integer is equal to the argument Integer;
less than 0	if this Integer is less than the argument Integer;
greater than 0	if this Integer is greater than the argument Integer.

Let's look at an example.

public class Main {
  public static void main(String[] args) {
/*from   j ava  2s  . c om*/
    Integer integer1 = new Integer("1");
    Integer integer2 = new Integer("2");
    
    System.out.println(integer1.compareTo(integer2));

  }
}

The output:

Reverse and rotate the integer in binary format

static int reverse(int i) reverses the bits.
static int reverseBytes(int i) reverses the bytes.
static int rotateLeft(int i, int distance) rotates the bits by distance to left.
static int rotateRight(int i, int distance) rotates the bits by distance to right.

The following code reverse decimal value 10 in binary format.

public class Main {
  public static void main(String[] args) {
// ja  v a 2 s. c  o m
    System.out.println(Integer.reverse(10));

  }
}

The output:

The following code rotates value 10 to left for distance of 2.

public class Main {
  public static void main(String[] args) {
/* j av  a  2 s  .c om*/
    System.out.println(Integer.rotateLeft(10,2));

  }
}

The output:

Bit oriented operation

static int bitCount(int i) counts the bits
static int highestOneBit(int i) returns an int value with at most a single one-bit, in the position of the highest-order ("leftmost") one-bit.
static int lowestOneBit(int i) returns an int value with at most a single one-bit, in the position of the lowest-order ("rightmost") one-bit.

The following code does the bit oriented operation on value 10.

public class Main {
  public static void main(String[] args) {
/*from j a v  a2  s .  co m*/
    System.out.println(Integer.bitCount(10));
    System.out.println(Integer.highestOneBit(10));
    System.out.println(Integer.lowestOneBit(10));
  }
}

The output:

Get the sign of an Integer

static int signum(int i) returns the signum.

The possible values returned from signum(int i) are listed below:

Value	Meaning
-1	if i is negative;
0	if i is zero;
1	if i is positive.

In the following code we pass in constant value 10 to signum(int i).

public class Main {
  public static void main(String[] args) {
//from j  a v  a 2  s .  c om
    System.out.println(Integer.signum(10));
  }
}

The output:

Get the leading and trailing zeros

static int numberOfLeadingZeros(int i) returns the number of zero bits preceding the highest-order ("leftmost") one-bit
static int numberOfTrailingZeros(int i) returns the number of zero bits following the lowest-order ("rightmost") one-bit

public class Main {
  public static void main(String[] args) {
//  j  a v a2  s.  c  o  m
    System.out.println(Integer.numberOfLeadingZeros(10));
  }
}

The output:

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