Question

In Java Let’s say we’re designing a Student class that has two data fields. One data field, called id, is for storing each student’s ID number. Another data field, called numStudents, keeps track of how many Student objects have been created. For each of the blanks, indicate the appropriate choice.
id should be   public/private   and   static/not static .
numStudents should be   public/private   and   static/not static .

The next three questions use the following class:
class Counter {
    private int count;
  
    public Counter() {
        this(0);
    }
  
    public Counter(int startingCount) {
        count = startingCount;
    }
  
    public void increment() {
        count++;
    }
  
    public int getCount() {
        return count;
    }

    public void setCount(int count) {
        this.count = count;
    }
}

Here is one program using the above class:
public class Main {
   public static void main(String[] args) {
       Counter c1 = new Counter();
       Counter c2 = new Counter(5);
       swap(c1.getCount(), c2.getCount());
       System.out.print(c1.getCount() + " " +
                           c2.getCount());
   }
  
   public static void swap(int c1, int c2) {
        int temp = c1;
        c1 = c2;
        c2 = temp;
   }
}
If you run the program, you’ll see that the output is:
0 5
Explain using words and/or pictures why that is the output.

Here is a second program using the above class:
public class Main {
   public static void main(String[] args) {
       Counter c1 = new Counter();
       Counter c2 = new Counter(5);
       swap(c1, c2);
       System.out.print(c1.getCount() + " " +
                           c2.getCount());
   }
  
   public static void swap(Counter c1, Counter c2) {
        Counter temp = c1;
        c1 = c2;
        c2 = temp;
   }
}
If you run the program, you’ll see that the output is:
0 5
Explain using words and/or pictures why that is the output.

Here is a third program using the above class:
public class Main {
   public static void main(String[] args) {
       Counter c1 = new Counter();
       Counter c2 = new Counter(5);
       swap(c1, c2);
       System.out.print(c1.getCount() + " " +
                           c2.getCount());
   }
  
   public static void swap(Counter c1, Counter c2) {
        int temp = c1.getCount();
        c1.setCount(c2.getCount());
        c2.setCount(temp);
   }
}
If you run the program, you’ll see that the output is:
5 0
Explain using words and/or pictures why that is the output.

Answer 1

Answer 1:
id should be private and non static:
numStudents should be public and static

Answer 2:
because c1 and c2 has 0 and 5 we are calling swap function
but here the we are passing parameters using call by value
so that swap occured in that function will not have impact at main

Answer 3:
because c1 and c2 has 0 and 5 we are calling swap function
but here the we are passing parameters using call by value
so that swap occured in that function will not have impact at main

Answer 4:here we are changing the values of c1 and c2 in swap function so the chages will
have effect at main