Syntax error What are the restrictions on increment and decrement operators in java?

What are the restrictions on increment and decrement operators in java?

The increment operator increments the value of the operand by 1 and the decrement operator decrements the value of the operand by 1. We use these operators to increment or, decrement the values of the loop after executing the statements on a value.

Example

 Live Demo

public class ForLoopExample {
   public static void main(String args[]) {
      //Printing the numbers 1 to 10
      for(int i = 1; i<=10; i++) {
         System.out.print(" "+i);
      }
      System.out.println(" ");
      //Printing the numbers 10 to 1
      for(int i = 10; i>=1; i--) {
         System.out.print(" "+i);
      }
   }
}

Output

1 2 3 4 5 6 7 8 9 10
10 9 8 7 6 5 4 3 2 1

Restrictions on increment and decrement operators

  • You cannot use increment and decrement operators with constants, if you do so, it generates a compile time error.

Example

public class ForLoopExample {
   public static void main(String args[]) {
      int num = 20;
      System.out.println(num++);
      System.out.println(20--);
   }
}

Output

ForLoopExample.java:5: error: unexpected type
      System.out.println(20--);
                        ^
   required: variable
   found: value
1 error
  • You cannot nest two increment or decrement operators in Java, if you do so, it generates a compile time error −

Example

public class ForLoopExample {
   public static void main(String args[]) {
      int num = 20;
      System.out.println(--(num++));
   }
}

Output

ForLoopExample.java:4: error: unexpected type
      System.out.println(--(num++));
                               ^
required: variable
found: value
1 error
  • Once you declare a variable final you cannot modify its value. Since increment or, decrement operators changes the values of the operands. Usage of these operators with a final variable is not allowed.

Example

public class ForLoopExample {
   public static void main(String args[]) {
      final int num = 20;
      System.out.println(num++);
   }
}

Output

ForLoopExample.java:4: error: cannot assign a value to final variable num
   System.out.println(num++);
                      ^
1 error
  • Usage of increment and decrement operators with boolean variables is not allowed. If you still, try to increment or decrement a boolean value a compile time error is generated.

Example

public class ForLoopExample {
   public static void main(String args[]) {
      boolean bool = true;
      System.out.println(bool++);
   }
}

Output

ForLoopExample.java:4: error: bad operand type boolean for unary operator '++'
      System.out.println(bool++);
                            ^
1 error
Updated on: 2019-07-30T22:30:26+05:30

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