Relational operators in Java - Cheat Sheet & Quick Revision

Recall & Review

beginner

What are relational operators in Java?

Relational operators compare two values and return a boolean result: true or false. They help decide if one value is greater, smaller, equal, or not equal to another.

beginner

List the six main relational operators in Java.

The six main relational operators are: < (less than), > (greater than), <= (less than or equal to), >= (greater than or equal to), == (equal to), != (not equal to).

beginner

What is the result type of a relational operator expression in Java?

The result is always a boolean value: either true or false.

beginner

Explain the difference between == and = in Java.

== is a relational operator that checks if two values are equal. = is an assignment operator that sets a value to a variable.

beginner

What will be the output of this code snippet? int a = 5, b = 10; System.out.println(a > b);

The output will be false because 5 is not greater than 10.

Which operator checks if two values are NOT equal in Java?

A <=

B ==

C !=

D =

!= means not equal, so it returns true if values differ.

What is the result type of the expression (5 < 10)?

A boolean

B int

C String

D double

Relational operators always return a boolean value: true or false.

Which operator would you use to check if a number is greater than or equal to another?

A <=

B >=

C ==

D !=

>= means greater than or equal to.

What does the expression (a == b) check?

A If a is equal to b

B If a is not equal to b

C If a is greater than b

D If a is assigned b

== checks if two values are equal.

Which of these is NOT a relational operator in Java?

A >=

B !=

C <

D &&

&& is a logical AND operator, not a relational operator.

Explain what relational operators do in Java and give examples.

Think about how you compare numbers or values in daily life.

Describe the difference between == and = in Java and why confusing them can cause errors.

One is for comparison, the other for setting values.

Practice

1. Which of the following relational operators in Java checks if two values are not equal?

easy

A. ==

B. >=

C. !=

D. <

Solution

1. Step 1: Understand the meaning of relational operators

   Relational operators compare two values and return true or false based on the comparison.

2. Step 2: Identify the operator for 'not equal'

   The operator '!=' means 'not equal to' in Java.

3. Final Answer:

   != -> Option C

4. Quick Check:

   Not equal operator = != [OK]

Hint: Remember: '!=' means not equal in Java [OK]

Common Mistakes:

• Confusing '!=' with '=='
• Using '=' instead of '=='
• Mixing up '<' and '<='

2. Which of the following is the correct syntax to check if variable a is greater than or equal to variable b in Java?

easy

A. a => b

B. a >= b

C. a =< b

D. a =>= b

Solution

1. Step 1: Recall the correct relational operator syntax

   The operator for 'greater than or equal to' is written as '>=' in Java.

2. Step 2: Check each option for correct syntax

   a >= b uses '>=', which is correct. Other options have invalid syntax.

3. Final Answer:

   a >= b -> Option B

4. Quick Check:

   Greater or equal operator = >= [OK]

Hint: Use '>=' for greater or equal, not '=>' or '=<' [OK]

Common Mistakes:

• Writing '=>' instead of '>='
• Using '=' instead of '=='
• Confusing '<=' and '=>'

3. What will be the output of the following Java code?

int x = 5;
int y = 10;
System.out.println(x < y);
System.out.println(x == y);
System.out.println(x != y);

medium

A. false false true

B. false true false

C. true true false

D. true false true

Solution

1. Step 1: Evaluate each relational expression

   x is 5 and y is 10. So, x < y is true, x == y is false, and x != y is true.

2. Step 2: Write the output in order

   The printed output will be: true false true.

3. Final Answer:

   true false true -> Option D

4. Quick Check:

   5 < 10 = true, 5 == 10 = false, 5 != 10 = true [OK]

Hint: Compare values step-by-step to get true/false results [OK]

Common Mistakes:

• Mixing up == and !=
• Assuming x == y is true
• Confusing output order

4. Identify the error in the following Java code snippet:

int a = 7;
int b = 3;
if (a <> b) {
    System.out.println("Not equal");
}

medium

A. The operator '<>' is invalid in Java

B. Missing semicolon after if statement

C. Variables a and b are not declared

D. The print statement syntax is incorrect

Solution

1. Step 1: Check the relational operator used

   The operator '<>' is not a valid relational operator in Java. Java uses '!=' for not equal.

2. Step 2: Verify other syntax elements

   Semicolons and print statement are correct. Variables are declared properly.

3. Final Answer:

   The operator '<>' is invalid in Java -> Option A

4. Quick Check:

   Use '!=' for not equal, not '<>' [OK]

Hint: Use '!=' for not equal; '<>' is invalid in Java [OK]

Common Mistakes:

• Using '<>' instead of '!='
• Forgetting semicolons
• Incorrect print syntax

5. Given the code below, what will be the output?

int a = 4;
int b = 4;
int c = 5;
boolean result = (a <= b) && (c > b);
System.out.println(result);

Choose the correct output.

hard

A. true

B. false

C. Compilation error

D. Runtime exception

Solution

1. Step 1: Evaluate each relational expression

   a <= b is 4 <= 4, which is true. c > b is 5 > 4, which is true.

2. Step 2: Evaluate the logical AND operation

   Both conditions are true, so (true && true) is true.

3. Final Answer:

   true -> Option A

4. Quick Check:

   4 <= 4 and 5 > 4 = true [OK]

Hint: Both conditions must be true for && to be true [OK]

Common Mistakes:

• Confusing && with ||
• Misreading <= as < only
• Assuming false if equal values