trophyChallenge - 5 Problems

🎖️

Default Access Master

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Test your skills under time pressure!

💻 code output

intermediate

2:00remaining

Output of default access modifier in same package

What is the output of this Java code when both classes are in the same package?

Java

class A {
    int number = 10; // default access
}

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

A10

BCompilation error: number has private access in A

CCompilation error: number is not public in A

DRuntime error

Attempts:

2 left

💻 code output

intermediate

2:00remaining

Accessing default member from different package

What happens when you try to access a default access member from a class in a different package?

Java

package pkg1;
class B {
    int value = 5; // default access
}

package pkg2;
import pkg1.B;
public class Test {
    public static void main(String[] args) {
        B b = new B();
        System.out.println(b.value);
    }
}

BCompilation error: value is not public in B

CCompilation error: B() has private access in B

DRuntime error: IllegalAccessException

Attempts:

2 left

🔧 debug

advanced

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Why does this code fail to compile?

This code tries to access a default access method from another package. Identify the cause of the compilation error.

Java

package pkg1;
class C {
    void show() { System.out.println("Hello"); } // default access
}

package pkg2;
import pkg1.C;
public class Test {
    public static void main(String[] args) {
        C c = new C();
        c.show();
    }
}

AClass C is abstract and cannot be instantiated

BClass C is public but method show() is private

CMethod show() has default access and is not visible outside pkg1

DMethod show() is static and should be called on class

Attempts:

2 left

🧠 conceptual

advanced

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Default access modifier and subclassing

If a class with default access modifier is subclassed in the same package, can the subclass access the default members of the superclass?

ANo, default members are only accessible within the same class

BNo, default members are not accessible to subclasses even in the same package

CYes, but only if the subclass is in a different package

DYes, default members are accessible to subclasses in the same package

Attempts:

2 left

💻 code output

expert

2:00remaining

Number of accessible members with default access

Given this class with default access members, how many members are accessible from another class in the same package?

Java

class D {
    int a = 1; // default
    private int b = 2;
    protected int c = 3;
    public int d = 4;
}

Attempts:

2 left