Static Output Questions

 https://www.scientecheasy.com/2021/10/java-static-interview-questions.html/

1) 

public class Myclass 

{

   private int x = 10;

   static int m1() {

       int y = x;

       return y;

   }

   public static void main(String[] args) {

     m1();

   }

}


Ans: No, the above code will not be compiled because x is an instance variable and instance member cannot be accessed from static region.

2) 

public class Myclass 
{
   private int x = 10;
   static int m1()
   {
      Myclass obj = new Myclass();
      int y = obj.x;
      return y;
   }
   public static void main(String[] args) {
      System.out.println(m1());
   }
}

Ans: There is no error in the above code snippet. Output: 10.


3) 
public class Myclass 
{
   static int a = 20;
   static int b = 30;
   static int c = 40;
   Myclass() 
   {
      a = 200;
   }
   static void m1() {
      b = 300;
   }
   static {
      c = 400;
   }
   public static void main(String[] args) {
      System.out.println(a);
      System.out.println(b);
      System.out.println(c);
   }
}

Ans: Output: 20, 30, 400.

4) 
public class Myclass {
    static int a = 20;
    Myclass() {
       a = 200;
    }
public static void main(String[] args) {
    new Myclass();
    System.out.println(a);
  }
}

Output: 200.

5)

public class Myclass {
   static int a = 20;
   Myclass() {
      a++;
   }
   void m1()  {
      a++;
      System.out.println(a);
   }
public static void main(String[] args) 
{
    Myclass obj = new Myclass();
    Myclass obj2 = new Myclass();
    Myclass obj3 = new Myclass();
       obj3.m1();
   }
}

Ans: Output: 24.

6) 
public class Test
{
   Test() {
       m2();
   }
   void m1() {
       System.out.println("Instance method");
   }
   static void m2() {
       System.out.println("Static method");
       m1();
   }
public static void main(String[] args)
{
     new Test();
  }
}

There is an error inside the static method because we cannot make a static reference to the non-static method m1() from the type Test.

7) 

public class Test
{
  Test(Test t) {
    m1();
    System.out.println("Constructor");
  }
  void m1() {
    m2();
    System.out.println("Instance method");
  }
  static void m2() {
     System.out.println("Static method");
  }
public static void main(String[] args)
{
     new Test(null);
  }
}

Yes, the above code will be  compiled successfully. There is no problem. Output: Static method, Instance method, Constructor.

8) 

public class Test { void m1(Test test) { System.out.println("Instance method"); } static void m1(Test t) { System.out.println("Static method"); } }

Yes, Duplicate method error. This is because we cannot declare a static method and instance method with the same signature in the same class.

9)

public class Myclass {
   static int a = 20;
   static void m2() {
        a++;
   }
public static void main(String[] args) {
    System.out.println(a);
  }
}

Output: 20.

10)

public class Myclass {
   static int a = 20;
   static {
        a++;
   }
   {
     a++;
     System.out.println(a);
   }
public static void main(String[] args) 
{
   Myclass obj = new Myclass();
   Myclass obj2 = new Myclass();
   Myclass obj3 = new Myclass();
  }
}

Ans: Output: 22, 23, 24.

11)

public class Myclass {
  Myclass() {
      System.out.println("constructor");
  }
  static void m1() {
      System.out.println("static method");
  }
  void m2(){
      System.out.println("instance method");
  }
  static {
      System.out.println("static block");
  }
  {
      System.out.println("instance block");
  }
public static void main(String[] args) 
{
    Myclass obj = new Myclass();
    m1();
    obj.m2();
   }
}

Ans: Output: static block, instance block, constructor, static method, instance method.


12)

public class Myclass {
  static {
     System.out.println("static block");
  }
  {
     System.out.println("instance block");
  }
public static void main(String[] args) {
    Myclass obj = new Myclass();
    Myclass obj2 = new Myclass();
    Myclass obj3 = new Myclass();
  }
}

Ans: Output: static block, instance block, instance block, instance block.


13)

public class Myclass {
  private static int x = 10;
  static {
      x++;
  }
  static {
      ++x;
  }
  {
      x--;
  }
public static void main(String[] args) {
    Myclass obj = new Myclass();
    Myclass obj2 = new Myclass();
    Myclass obj3 = new Myclass();
    System.out.println(x);
  }
}

Ans: Yes, the code will be  compiled fine. The output is 9.

14) 

class demo {

    static{
        System.out.println("hello");
    }
    public static final int i =10;
}
public class test3 {
    public static void main(String[] args) {
        System.out.println(demo.i);
    }
}
Ans : it will print 10 (compiler optimization : in common memeory location so it will not load the class)

15)

class Test1 { 
public
    static void main(String[] args) 
    { 
        int x = 20; 
        System.out.println(x); 
    } 
    static
    { 
        int x = 10; 
        System.out.print(x + " "); 
    } 
} 

output: 10 20

16)

class Test1 {
    int x = 10;
public
    static void main(String[] args)
    {
        System.out.println(x);
    }
    static
    {
        System.out.print(x + " ");
    }
}

output: Error

17)

class Test1 {
    int x = 10;
public
    static void main(String[] args)
    {
        System.out.println(Test1.x);
    }
    static
    {
        int x = 20;
        System.out.print(x + " ");
    }
}

We can not access the instance variable with class name. otherwise it will give the error : non-static variable x cannot be referenced from a static context



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