Question

1. Identify a logical error in the following code and fix it.

public class test1 {
    public static void main(String[] args){
        int total;
        float avg;
        int a, b, c;
        a=10;
        b=5;
        c=2;
        total=a+b+c;
        avg=total/3;
        System.out.println("Average: "+avg);
    }
}

Answer:

2. Write the output of the program below.

import java.util.Scanner;

public class test2 {

    public static void main(String[] arg){

        int psid;

        String name;

        Scanner input=new Scanner(System.in);

        System.out.println("Enter your PSID");

        psid=input.nextInt();

        System.out.println("Enter your Name");

        name=input.nextLine();



        System.out.println("Name: "+ name);

        System.out.println("PSID: "+psid);

    }

}

Did the program produced expected output?

If your answer is “yes”, then justify your answer. Else if your answer is “no”, then what is the reason for that and how to fix it?

Answer 1

public class test1 {
public static void main(String[] args){
int total;
float avg;
int a, b, c;
a=10;
b=5;
c=2;
total=a+b+c;
avg=total/3.0f;
System.out.println("Average: "+avg);
}
}

Answer:
=====
The fixed code is given above. The error is in calculating average. We need to use 3.0f instead of 3, otherwise it will perform integer division and we will loose the fractional part. Using 3.0f will ensure that we get float as result without loosing data.

output of program
====
Average: 5.6666665

*******************************************
import java.util.Scanner;

public class test2{
   public static void main(String[] arg){

   int psid;

   String name;

   Scanner input=new Scanner(System.in);

   System.out.println("Enter your PSID");

   psid=input.nextInt();
   input.nextLine(); //get rid of newline before reading name
  
  
   System.out.println("Enter your Name");

   name=input.nextLine();

   System.out.println("Name: "+ name);

   System.out.println("PSID: "+psid);

   }
}

output:
=======
Enter your PSID
12
Enter your Name
John
Name: John
PSID: 12

Answer:
=====
The fixed program is given above. The program would not read the name input from user. This is because after the integer for Id is input, there is a newline which is taken by nextLine() method. It would not wait for user to type in name. So avoid the problem, we use input.nextLine() after reading the int input. This removes the newline from input and waits for user input of name after prompting.