Logical Operators

• Logical operators are used to form logical expressions.
• The operands of these operators will be boolean type.
• Result of logical expression will be boolean type i.e. true or false.

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Logical Operators Table

| Logical Operator | Description | | ---------------- | ----------- | --- | ---------- | | ! | Logical NOT | | && | Logical AND | | | | | Logical OR |

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6.1 Logical NOT Operator

• It is a unary operator.
• It is used to inverse the result.

Truth Table

Operand	Result
true	false
false	true

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Lab138.java

class Lab138 {

  public static void main(String[] args) {
    System.out.println(!true);
    System.out.println(!false);
  }
}

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Lab139.java

class Lab139 {

  public static void main(String[] args) {
    int a = 10;
    System.out.println(!a);
  }
}

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Lab140.java

class Lab140 {

  public static void main(String[] args) {
    int a = 10;
    System.out.println(!a == 10);
  }
}

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Lab141.java

class Lab141 {

  public static void main(String[] args) {
    int a = 10;
    System.out.println(!(a == 10));
  }
}

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Logical OR and Logical AND

• These are binary operators.
• Logical OR and Logical AND operators are used to combine two relational expressions to form logical expressions.

Example:

(a>b)&& (a>c)
(a<b)|| (a<c)

6.2 Logical AND Operator (&&)

• Result of Logical AND is true if both the operands are true otherwise false.

Truth Table

OP1	OP2	Result
true	true	true
true	false	false
false	true	false
false	false	false

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Lab142.java

class Lab142 {

  public static void main(String as[]) {
    System.out.println(true && true);
    System.out.println(true && false);
    System.out.println(false && true);
    System.out.println(false && false);
  }
}

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Lab143.java

class Lab143 {

  public static void main(String as[]) {
    int a = 99;
    long b = 65799999;

    boolean b1 = (a == 99) && (b == 65799999);
    boolean b2 = (a == 99) && (b == 65799990);

    System.out.println(b1);
    System.out.println(b2);
  }
}

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Lab144.java

class Lab144 {

  public static void main(String as[]) {
    int a = 12;
    boolean b = a > 10 && a++ < 5;

    System.out.println(a);
    System.out.println(b);
  }
}

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Lab145.java

class Lab145 {

  public static void main(String as[]) {
    int a = 12;
    boolean b = a > 15 && a++ < 5;

    System.out.println(a);
    System.out.println(b);
  }
}

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6.3 Logical OR Operator (||)

• Result of Logical OR is false if both operands are false, otherwise true.

Truth Table

OP1	OP2	Result
true	true	true
true	false	true
false	true	true
false	false	false

Lab146.java

class Lab146 {

  public static void main(String[] args) {
    System.out.println(true || true);
    System.out.println(true || false);
    System.out.println(false || true);
    System.out.println(false || false);
  }
}

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Lab147.java

class Lab147 {

  public static void main(String[] args) {
    int a = 99;
    long b = 65799999;

    boolean b1 = (a == 99) || (b == 65799999);
    boolean b2 = (a == 99) || (b == 65799990);
    boolean b3 = (a == 88) || (b == 65799990);

    System.out.println(b1);
    System.out.println(b2);
    System.out.println(b3);
  }
}

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Lab148.java

class Lab148 {

  public static void main(String[] args) {
    int a = 12;
    boolean b = a > 10 || a++ < 5;

    System.out.println(a);
    System.out.println(b);
  }
}

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Lab149.java

class Lab149 {

  public static void main(String[] args) {
    int a = 12;
    boolean b = a > 15 || a++ < 5;

    System.out.println(a);
    System.out.println(b);
  }
}