Java OCA OCP Practice Question 1168

Question

Which line of code, inserted at line p1, causes the application to print 5? 

package mypkg; //  w  w  w.jav  a 2  s .co  m
public class Main { 
        private int v = 1; 
        protected boolean outside; 

        public Main() { 
           // p1 
           outside = true; 
        } 

        public Main(int v) { 
           this.v = outside ? v : v+1; 
        } 

        public static void main(String[] bounce) { 
           System.out.print(new Main().v); 
        } 
}
  • A. this(4);
  • B. new Main(4);
  • C. this(5);
  • D. v = 4; 


A.

Note

All of the lines compile but they produce various different results.

The default initialization of a boolean instance variable is false, making outside false at line p1.

this(4) will cause v to be set to 5, while this(5) will cause v to be set to 6.

Since 5 is the number we are looking for, Option A is correct, and Option C is incorrect.

Option B is incorrect.

While the statement does create a new instance of Main, with v having a value of 5, that instance is nested and the value of v does not affect the surrounding instance of Main that the constructor was called in.

Option D is also incorrect.

The value assigned to v is 4, not the target 5.




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