Relational operators in Java - Practice Problems & Coding Challenges

Challenge - 5 Problems

❓ Predict Output

intermediate

Output of relational operators with integers

What is the output of this Java code snippet?

Java

public class Main {
    public static void main(String[] args) {
        int a = 5;
        int b = 10;
        System.out.println(a > b);
        System.out.println(a <= b);
    }
}

A false\nfalse

B true\nfalse

C false\ntrue

D true\ntrue

💡 Hint

Remember that 5 is less than 10, so a > b is false.

Since 5 is not greater than 10, a > b is false. Since 5 is less than or equal to 10, a <= b is true.

❓ Predict Output

intermediate

Relational operators with characters

What will this Java program print?

Java

public class Main {
    public static void main(String[] args) {
        char x = 'A';
        char y = 'a';
        System.out.println(x < y);
        System.out.println(x == y);
    }
}

A false\nfalse

B false\ntrue

C true\ntrue

D true\nfalse

💡 Hint

Characters are compared by their Unicode values.

The Unicode value of 'A' (65) is less than 'a' (97), so x < y is true. They are not equal, so x == y is false.

❓ Predict Output

advanced

Relational operators with floating-point numbers

What is the output of this Java code?

Java

public class Main {
    public static void main(String[] args) {
        double d1 = 0.1 + 0.2;
        double d2 = 0.3;
        System.out.println(d1 == d2);
        System.out.println(d1 > d2);
    }
}

A false\ntrue

B false\nfalse

C true\ntrue

D true\nfalse

💡 Hint

Floating-point arithmetic can cause precision issues.

Due to floating-point precision, 0.1 + 0.2 is not exactly 0.3 but slightly larger, so d1 == d2 is false and d1 > d2 is true.

❓ Predict Output

advanced

Relational operators with boolean values

What will this Java program print?

Java

public class Main {
    public static void main(String[] args) {
        boolean b1 = true;
        boolean b2 = false;
        System.out.println(b1 == b2);
        System.out.println(b1 != b2);
    }
}

A false\ntrue

B true\nfalse

C false\nfalse

D true\ntrue

💡 Hint

Boolean values can be compared with == and != operators.

b1 is true and b2 is false, so b1 == b2 is false and b1 != b2 is true.

❓ Predict Output

expert

Relational operators with mixed types and casting

What is the output of this Java code?

Java

public class Main {
    public static void main(String[] args) {
        int i = 10;
        double d = 10.0;
        System.out.println(i == d);
        System.out.println(i >= d);
        System.out.println((double) i > d);
    }
}

A eslafn\eurtn\eurt

B true\ntrue\nfalse

C rue\ntrue\nfalse

D true\ntrue\nfals

💡 Hint

When comparing int and double, int is promoted to double.

i == d is true because 10 equals 10.0. i >= d is true for the same reason. (double) i > d is false because 10.0 is not greater than 10.0.

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