Method calling in Java - Practice Problems & Coding Challenges

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Challenge - 5 Problems

💻 code output

intermediate

Output of method call with recursion

What is the output of this Java program when the printNumbers method is called with argument 3?

Java

public class Test {
    public static void printNumbers(int n) {
        if (n == 0) return;
        System.out.print(n + " ");
        printNumbers(n - 1);
    }

    public static void main(String[] args) {
        printNumbers(3);
    }
}

A 3 2 1

B 1 2 3

C 3 2 1 0

D 0 1 2 3

💻 code output

intermediate

Output of method call with overloaded methods

What is the output of this Java program?

Java

public class OverloadTest {
    public static void display(int a) {
        System.out.println("int: " + a);
    }

    public static void display(String a) {
        System.out.println("String: " + a);
    }

    public static void main(String[] args) {
        display(5);
        display("hello");
    }
}

A

int: 5
String: hello

B

String: 5
int: hello

C

int: 5
int: hello

D

String: 5
String: hello

🔧 debug

advanced

Identify the error in method call

What error does this Java code produce when compiled?

Java

public class ErrorTest {
    public static void greet() {
        System.out.println("Hello");
    }

    public static void main(String[] args) {
        greet("World");
    }
}

A Runtime error: NullPointerException

B Compilation error: method greet() in class ErrorTest cannot be applied to given types

C Compilation error: missing return statement

D No error, prints "Hello World"

💻 code output

advanced

Output of method call with static and instance methods

What is the output of this Java program?

Java

public class StaticInstance {
    public static void staticMethod() {
        System.out.println("Static method called");
    }

    public void instanceMethod() {
        System.out.println("Instance method called");
    }

    public static void main(String[] args) {
        StaticInstance.staticMethod();
        StaticInstance obj = new StaticInstance();
        obj.instanceMethod();
    }
}

A

Static method called
Static method called

B

Instance method called
Static method called

C

Static method called
Instance method called

D

Instance method called
Instance method called

💻 code output

expert

Output of method call with method overriding and polymorphism

What is the output of this Java program?

Java

class Parent {
    void show() {
        System.out.println("Parent show");
    }
}

class Child extends Parent {
    @Override
    void show() {
        System.out.println("Child show");
    }
}

public class TestPolymorphism {
    public static void main(String[] args) {
        Parent obj = new Child();
        obj.show();
    }
}

A Runtime error: ClassCastException

B Parent show

C Compilation error: cannot override show()

D Child show