trophyChallenge - 5 Problems

🎖️

Private Access Master

Get all challenges correct to earn this badge!

Test your skills under time pressure!

💻 code output

intermediate

2:00remaining

Output of accessing private field within the same class

What is the output of this Java program?

Java

public class Test {
    private int number = 5;
    public void printNumber() {
        System.out.println(number);
    }
    public static void main(String[] args) {
        Test t = new Test();
        t.printNumber();
    }
}

CCompilation error: number has private access in Test

DRuntime error

Attempts:

2 left

💻 code output

intermediate

2:00remaining

Output when accessing private field from another class

What happens when you try to compile and run this code?

Java

public class A {
    private int secret = 10;
}

public class B {
    public static void main(String[] args) {
        A a = new A();
        System.out.println(a.secret);
    }
}

A10

BRuntime error: IllegalAccessException

DCompilation error: secret has private access in A

Attempts:

2 left

🔧 debug

advanced

2:00remaining

Why does this code cause a compilation error?

Identify the reason for the compilation error in this code snippet.

Java

class Person {
    private String name;
    public Person(String name) {
        this.name = name;
    }
}

class Employee extends Person {
    public Employee(String name) {
        super(name);
    }
    public void printName() {
        System.out.println(name);
    }
}

AMissing return type in printName method

BConstructor call super(name) is invalid

CCannot access private field 'name' in subclass Employee

DNo compilation error

Attempts:

2 left

📝 syntax

advanced

2:00remaining

Which option correctly declares a private method and calls it within the same class?

Select the code snippet that compiles and runs correctly, printing "Hello".

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

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

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

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

Attempts:

2 left

🚀 application

expert

2:00remaining

How many private fields are accessible in this nested class?

Given the code below, how many private fields of Outer are accessible directly inside Inner?

Java

public class Outer {
    private int a = 1;
    private int b = 2;
    int c = 3;
    public class Inner {
        public int sum() {
            return a + b + c;
        }
    }
}

Attempts:

2 left