Java Tutorial - Java Boolean Operator

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The Boolean logical operators operate on boolean operands.

Logical Operator List

The following table lists all Java boolean logical operators.

True table

The following table shows the effect of each logical operation:

The following program demonstrates the boolean logical operators.

 
public class Main {
  public static void main(String args[]) {
    boolean a = true;
    boolean b = false;
    boolean c = a | b;
    boolean d = a & b;
    boolean e = a ^ b;
    boolean f = (!a & b) | (a & !b);
    boolean g = !a;
    System.out.println(" a = " + a);
    System.out.println(" b = " + b);
    System.out.println(" a|b = " + c);
    System.out.println(" a&b = " + d);
    System.out.println(" a^b = " + e);
    System.out.println("!a&b|a&!b = " + f);
    System.out.println(" !a = " + g);
//  www  .  j  a v  a2  s.c om
  }
}
]]>

The output:

Example

The following program demonstrates the bitwise logical operators:

 
public class Main {
  public static void main(String args[]) {
    int a = 1;//from  w w  w . j av  a2 s. c o  m
    int b = 2;
    int c = a | b;
    int d = a & b;
    int e = a ^ b;
    int f = (~a & b) | (a & ~b);
    int g = ~a & 0x0f;
    System.out.println(" a = " + a);
    System.out.println(" b = " + b);
    System.out.println(" a|b = " + c);
    System.out.println(" a&b = " + d);
    System.out.println(" a^b = " + e);
    System.out.println("~a&b|a&~b = " + f);
    System.out.println(" ~a = " + g);
  }
}

Here is the output from this program:

Java Logical Operators Shortcut

The OR operator results in true when one operand is true, no matter what the second operand is. The AND operator results in false when one operand is false, no matter what the second operand is. If you use the || and &&, Java will not evaluate the right-hand operand when the outcome can be determined by the left operand alone.

The following code shows how you can use short-circuit logical operator to ensure that a division operation will be valid before evaluating it:

 
public class Main {
  public static void main(String[] argv) {
    int denom = 0;
    int num = 3;// ww  w .  j  a v  a  2s  .  c  om
    if (denom != 0 && num / denom > 10) {
      System.out.println("Here");
    } else {
      System.out.println("There");
    }
  }
}

The output:

If we want to turn of the shortcut behaviour of logical operators we can use & and |.

Example 2

The following code uses a single & ensures that the increment operation will be applied to e whether c is equal to 1 or not.

 
public class Main {
  public static void main(String[] argv) {
    int c = 0;/*  www  .j  a  va2 s. c om*/
    int e = 99;
    int d = 0;
    if (c == 1 & e++ < 100)
      d = 100;
    System.out.println("e is " + e);
    System.out.println("d is " + d);
  }
}

The output:

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