Java operators

Java supports different types of operators. Here the Relational operators and the Logical operators are explained using Java Codes and exercises.

1- Relational Operators

Relational operators are binary operators, and their operands are numeric expressions. The result of the evaluation is either true or false.

Example is: if ( i == 20 )  this asks “does i equal to 20?” if it is true, the statement is executed. The statement is ignored if i is not equal to 20, because the result is false.

The relational operators in Java are:

Exercise 1

What is written to the standard output as the result of executing the following statements?

class RelationalOperator {

	public static void main(String[] args){

		int i = 8;

		if(i != 7) {
			System.out.print("X");
		}
		else {
			System.out.print("Y");
		}
	}
}

Select the correct answer.

a. This code writes “X” to the standard output.

b. This code writes “Y” to the standard output.

c. This code writes nothing to the standard output.

Exercise 2

What is written to the standard output as the result of executing the following statements?

class RationalOperator {

	public static void main(String[] args){

		int i = 100;

		if(i <= 30) {
			System.out.print("M");
		}
		else {
			System.out.print("O");
		}
	}
}

Select the correct answer.

a. This code writes “M” to the standard output.

b. This code writes “O” to the standard output.

c. This code writes “MO” to the standard output.

d. This code writes nothing to the standard output.

Exercise 3

What is written to the standard output as the result of executing the following statements?

class RelationalOperator {

	public static void main(String[] args){

		int i = 10;
		int i2 = 20;
		int i3 = 30;

		if(i3 <= 30) {
			System.out.print("K");
		}
		if(i == i3) {
			System.out.print("L");
		}
		if(i3 >= 22) {
			System.out.print("M");
		}
		if(i2 > 18) {
			System.out.print("N");
		}
		if(i != 10) {
			System.out.print("O");
		}
	}
}

Select the correct answer.

a. This code writes “KLN” to the standard output.

b. This code writes “LMN” to the standard output.

c. This code writes “KMN” to the standard output.

d. This code writes “MNO” to the standard output.

2- Conditional Operators

The conditional operators in Java ( &&, || ) are used in conditional statements such as if and while statements. The following example shows the difference between “&&” and “||”

int i = 4;   int r = 6;

if(i == 4 && r ==3 )  // By using  “&&” the result is false, because r is not equal to 3. One false results in false.

if(i ==4 || r ==3) // By using  “||”  the result is true, because i is equal to 4. One true results in true.

&&	AND
||	OR

Exercise 4

What is written to the standard output as the result of executing the following statements?

class LogicalOperator {

	public static void main(String[] args){

		int i = 10;

		if(i > 9 && i != 10) {
			System.out.print("P");
		}
		else {
			System.out.print("Q");
		}
	}
}

Select the correct answer.

a. This code writes “P” to the standard output.

b. This code writes “Q” to the standard output.

c. This code writes nothing to the standard output.

Exercise 5

What is written to the standard output as the result of executing the following statements?

class LogicalOperator {

	public static void main(String[] args){

		int i = 10;

		if(i != 9 || i > 20) {
			System.out.print("W");
		}
		else {
			System.out.print("Z");
		}
	}
}

Select the correct answer.

a. This code writes “W” to the standard output.

b. This code writes “Z” to the standard output.

c. This code writes nothing to the standard output.

Exercise 6

What is written to the standard output as the result of executing the following statements?

class LogicalOperator {

	public static void main(String[] args){

		int i = 10;
		int i2 = 20;
		int i3 = 30;

		if(i3 == 30 && i2 > 20) {
			System.out.print("R");
		}
		if(i != i3 || i2 == 21) {
			System.out.print("S");
		}
		if(i3 >= 22 && i != 11) {
			System.out.print("T");
		}
		if(i2 > 18 || i == 11) {
			System.out.print("U");
		}
	}
}

Select the correct answer.

a. This code writes “STU” to the standard output.

b. This code writes “RU” to the standard output.

c. This code writes “RSU” to the standard output.

d. This code writes “ST” to the standard output.

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Sar Maroof is a professional software development teacher, gives master classes and publishes technical articles. He is also an expert software developer and worked for several big as well as small companies and later as a freelancer.

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