Java compilation and execution flow - Practice Problems & Coding Challenges

Challenge - 5 Problems

❓ Predict Output

intermediate

Output of Java compilation and execution steps

What will be the output when the following Java program is compiled and run?

Java

public class Test {
    public static void main(String[] args) {
        System.out.println("Step 1");
        int x = 5;
        System.out.println("Value: " + x);
    }
}

A Runtime error

B Step 1 Value: 5

C Compilation error

D

Step 1
Value: 5

💡 Hint

Remember that System.out.println prints with a newline after the message.

The program prints "Step 1" followed by a newline, then prints "Value: 5" on the next line. So the output has two lines.

🧠 Conceptual

intermediate

Java compilation produces which file?

When you compile a Java source file named Example.java, what file is generated?

A Example.class

B Example.exe

C Example.java

D Example.jar

💡 Hint

Think about the file that the Java Virtual Machine runs.

The Java compiler creates a .class file containing bytecode that the JVM executes.

🔧 Debug

advanced

Identify the error in Java compilation

What error will the Java compiler report for this code?

Java

public class Demo {
    public static void main(String[] args) {
        System.out.println("Hello");
    }
}

A Runtime exception

B Class not found error

C Missing semicolon error

D No error, runs fine

💡 Hint

Check the end of the System.out.println statement.

The statement is missing a semicolon at the end, causing a compilation error.

❓ Predict Output

advanced

Output of Java program with static block and main

What is the output when this Java program is compiled and run?

Java

public class StaticDemo {
    static {
        System.out.println("Static block executed");
    }
    public static void main(String[] args) {
        System.out.println("Main method executed");
    }
}

A

Main method executed
Static block executed

B

Static block executed
Main method executed

C Static block executed

D Main method executed

💡 Hint

Static blocks run before main method when class loads.

The static block runs first when the class loads, then main runs.

🧠 Conceptual

expert

Java execution flow with multiple classes

Given two Java classes, Main and Helper, where Main calls Helper's static method, what is the correct order of compilation and execution?

A Compile Helper.java and Main.java, then run Main; Helper's static method runs when called.

B Run Main.java directly without compiling; Helper.java compiles automatically.

C Compile only Main.java; Helper.java is ignored.

D Compile Helper.java only; Main.java runs Helper's method automatically.

💡 Hint

Java requires all classes to be compiled before running the main class.

Both classes must be compiled before running Main. Helper's static method runs only when called.