Java Tricky Output Questions

Java tricky output questions focus on common pitfalls related to control flow, data types, autoboxing, operators, and method overloading. Each question follows a consistent structure for better clarity and quick understanding.

Question 1. Break Statement Outside Loop

Java

public class A {
    public static void main(String[] args)
    {
        if (true)
            break;
    }
}

Choices:

• a) Nothing
• b) Error

Answer: b) Error

Explanation:

• The break statement is valid only inside a loop or a switch block.
• Using break inside an if statement causes a compile-time error:"break outside switch or loop".

Question 2. Character Addition vs String Concatenation

Java

public class A {
    public static void main(String[] args)
    {
        System.out.println('j' + 'a' + 'v' + 'a');
    }
}

Choices:

• a) java
• b) Something else (Other than simple concatenation)

Answer: b) Something else (Other than simple concatenation)

Explanation:

• Character literals ('j', 'a', 'v', 'a') are treated as char, not String.
• The + operator performs numeric addition on character Unicode values.
• Calculation:106 + 97 + 118 + 97 = 418
• String concatenation would occur only with double-quoted literals.

Question 3. Valid Java Identifiers

Java

public class A {
    public static void main(String[] args)
    {
        int $_ = 5;
    }
}

Choices:

• a) Nothing
• b) Error

Answer: a) Nothing

Explanation:

• In Java, identifiers can start with: Letters, Underscore (_), Dollar sign ($)
• The variable name $_ is valid, so the program compiles and runs without output.  

Question 4. Integer Caching and Reference Comparison

Java

public class Demo{
    public static void main(String[] arr){
        Integer num1 = 100;
        Integer num2 = 100;
        Integer num3 = 500;
        Integer num4 = 500;
        
        if(num1==num2){
            System.out.println("num1 == num2");
        }
        else{
            System.out.println("num1 != num2");
        }
        if(num3 == num4){
            System.out.println("num3 == num4");
        }
        else{
            System.out.println("num3 != num4");
        }
    }
}

Choices:

• a) num1 == num2     num3 == num4
• b) num1 == num2     num3 != num4
• c) num1 != num2     num3 == num4
• d) num1 != num2     num3 != num4

Answer: b) num1 == num2               num3 != num4

Explanation:

• Java caches Integer objects in the range -128 to 127.
• Autoboxed values within this range reference the same object.
• 100 is cached → same reference → == returns true.
• 500 is not cached → different objects → == returns false.
• == compares object references, not values.

Question 5. Overloading the main() Method

Java

public class Demo {
    public static void main(String[] arr) {}
    public static void main(String arr) {}
}

Choices:

• a) Nothing
• b) Error

Answer: a) Nothing

Explanation:

• The main() method can be overloaded.
• The JVM only invokes main(String[] args) as the entry point.
• The overloaded main(String) method is ignored unless explicitly called.

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