Why static is needed in Java - Challenge Your Understanding

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Challenge - 5 Problems

🧠 conceptual

intermediate

Why use static methods in Java?

In Java, why do we use static methods instead of instance methods sometimes?

A Static methods are slower because they need an object to run.

B Static methods can access instance variables directly without an object.

C Static methods are used only for private data hiding.

D Static methods belong to the class and can be called without creating an object.

💻 code output

intermediate

Output of static vs instance variable access

What is the output of this Java code?

Java

class Test {
    static int count = 0;
    int id;
    Test() {
        count++;
        id = count;
    }
    public static void main(String[] args) {
        Test a = new Test();
        Test b = new Test();
        System.out.println(a.id + "," + b.id + "," + Test.count);
    }
}

A 1,2,2

B 2,2,2

C 1,1,2

D 0,0,0

💻 code output

advanced

What error occurs when accessing instance variable from static method?

What error does this Java code produce?

Java

class Demo {
    int x = 5;
    static void show() {
        System.out.println(x);
    }
    public static void main(String[] args) {
        show();
    }
}

A Compile-time error: non-static variable x cannot be referenced from a static context

B Runtime NullPointerException

C Prints 5

D Compile-time error: missing return statement

🧠 conceptual

advanced

Why is static block used in Java?

What is the main purpose of a static block in Java?

A To initialize instance variables before constructor runs

B To initialize static variables when the class is loaded

C To execute code only when an object is created

D To override static methods

🚀 application

expert

How many objects are created and what is output?

Consider this Java code. How many objects are created and what is printed?

Java

class Counter {
    static int count = 0;
    Counter() {
        count++;
    }
    public static void main(String[] args) {
        Counter c1 = new Counter();
        Counter c2 = new Counter();
        Counter c3 = c2;
        System.out.println(count);
    }
}

A 3 objects created, prints 3

B 3 objects created, prints 2

C 2 objects created, prints 2

D 2 objects created, prints 3