unexpected output in code in passing array in java

Question

I have been facing problems in passing array in java. The code is:

package input_output;

import static java.lang.System.out;
import java.util.Scanner;

public class InputOutput {
    private static Scanner sc;
    public static void main(String []args){
        sc = new Scanner(System.in);
        out.print("Enter the length of arrays   :\t");
        int n = sc.nextInt();
        Employee[] emp = new Employee[n];
        for(int i=0;i<n;i++){
            out.print("\nEnter name and age of " + (i+1) + " employee   :\t");
            emp[i] = new Employee();
            emp[i].setName(sc.nextLine());
            sc.nextLine();
            emp[i].setAge(sc.nextInt());
        }

        Operation operate = new Operation(emp,n);

        operate.printOnScreen();

    }
}

class Operation{ 
    Employee []emp;
    public Operation(Employee[] emp,int n){
        this.emp=emp;
        for(Employee e: this.emp)
          e = new Employee();
    }

    public void printOnScreen() { 
        for(Employee e : emp){
            e = new Employee();
            out.println("Name:\t" + e.getName() + "\t\tAge:\t" + e.getAge() + "\n");
        }
    }
}

Employee class is a simple bean containing getter and setter methods of age and name.

The output is coming :

Name: null
Age:0

What's my mistake?

Now I have changed the constructor to

public Operation(Employee[] emp, int n){
        this.emp=emp;
}

and removed the line:

e = new Employee();

from PrintOnScreen()

And the output is:

Name:
Age:21

What are you trying to achieve with both for(Employee e: this.emp) e = new Employee();? — Tom
– Tom, Commented Sep 5, 2014 at 11:08
Please refrain from changing the question so that it renders valid answers invalid. Changing the source code with the corrected version is not right. — Thorsten Dittmar
– Thorsten Dittmar, Commented Sep 5, 2014 at 11:17
How about also posting the code for the Employee class so we can see whether the getter/setter is correctly implemented? — Thorsten Dittmar
– Thorsten Dittmar, Commented Sep 5, 2014 at 11:32

Thorsten Dittmar · Accepted Answer · 2014-09-05 11:20:35Z

4

You're not outputting data from the array in the following code:

public void printOnScreen() 
{ 
    for(Employee e : emp)
    {
        e = new Employee(); // <<< THIS IS WRONG, AS e IS ALREADY SET BY LOOP!!
        out.println("Name:\t" + e.getName() + "\t\tAge:\t" + e.getAge() + "\n");
    }
}

This code creates a new e on every iteration of the loop => you're not outputting the entry from the array, but the freshly created one. The code should read

public void printOnScreen() 
{ 
    for(Employee e : emp)
    {
        out.println("Name:\t" + e.getName() + "\t\tAge:\t" + e.getAge() + "\n");
    }
}

Also, the following code doesn't make sense:

public Operation(Employee[] emp,int n){
    this.emp=emp;
    for(Employee e: this.emp)
      e = new Employee();
}

Why do you iterate over all the employees in this.emp to create new instances of Employee that are stored nowhere? Also, the n parameter is not used. This code should read:

public Operation(Employee[] emp)
{
    this.emp=emp;
}

edited Sep 5, 2014 at 11:20

answered Sep 5, 2014 at 11:01

Thorsten Dittmar

56.9k10 gold badges95 silver badges145 bronze badges

Sign up to request clarification or add additional context in comments.

2 Comments

sagar Over a year ago

i have done changes as u have said,, but the o/p is now: Name: Age:21 that means name is empty

Thorsten Dittmar Over a year ago

Well, as you didn't show us the implementation of Employee, it is impossible for us to tell where the problem is. My best guess is that getter and setter simply don't work.

Tom · Accepted Answer · 2014-09-05 11:26:31Z

To your second problem: (empty name fields)

The problem is the sc.nextInt() call. This reads an integer from the input stream but leaves the carriage return and line feed signs there. The next sc.nextLine() call will read these sign and nothing else. That way all names are filled with \r\n.

You can fix that in to ways:

public static void main(String []args){
    sc = new Scanner(System.in);
    out.print("Enter the length of arrays   :\t");
    int n = sc.nextInt();
    sc.nextLine(); // <-- new
    Employee[] emp = new Employee[n];
    for(int i=0;i<n;i++){
        out.print("\nEnter name and age of " + (i+1) + " employee   :\t");
        emp[i] = new Employee();
        emp[i].setName(sc.nextLine());
        //sc.nextLine(); // <-- removed 
        emp[i].setAge(sc.nextInt());
        sc.nextLine(); // <-- new
    }
    //..
}

Or

public static void main(String []args){
    sc = new Scanner(System.in);
    out.print("Enter the length of arrays   :\t");
    int n = Integer.parseInt(sc.nextLine()); // <-- changed
    Employee[] emp = new Employee[n];
    for(int i=0;i<n;i++){
        out.print("\nEnter name and age of " + (i+1) + " employee   :\t");
        emp[i] = new Employee();
        emp[i].setName(sc.nextLine());
        //sc.nextLine(); // <-- removed 
        emp[i].setAge(Integer.parseInt(sc.nextLine())); // <-- changed
    }
    //..
}

If this solves your second problem, please accept Thorsten Dittmars anwser for you main question.

Pranalee · Accepted Answer · 2014-09-05 11:06:24Z

1

While printing data, you are printing data of new employee and not the earlier employee object that you created.

answered Sep 5, 2014 at 11:06

Pranalee

3,4074 gold badges24 silver badges36 bronze badges

Comments

Andreas L. · Accepted Answer · 2014-09-05 11:11:47Z

0

Not sure, but I think Array is not copying content with "=" in Java. Change in class Operation

this.emp=emp;
for(Employee e: this.emp)
    e = new Employee();

to

for(int i=0; i<n; i++) {
    this.emp[i].setName(emp.getName());
    this.emp[i].setAge(emp.getAge());
}

Then change

operate.printOnScreen();

to

operate.printOnScreen(emp);

and

public void printOnScreen() { 
    for(Employee e : emp){
        e = new Employee();
        out.println("Name:\t" + e.getName() + "\t\tAge:\t" + e.getAge() + "\n");
    }
}

to

public void printOnScreen(Employee emp) { 
    for(Employee e : emp){
        out.println("Name:\t" + e.getName() + "\t\tAge:\t" + e.getAge() + "\n");
    }
}

answered Sep 5, 2014 at 11:11

Andreas L.

2,98125 silver badges25 bronze badges

3 Comments

Thorsten Dittmar Over a year ago

The problem has nothing to do with array copying.

Andreas L. Over a year ago

this.emp=emp; would copy the contents?

Thorsten Dittmar Over a year ago

Heave you heard of references?

Collectives™ on Stack Overflow

unexpected output in code in passing array in java

4 Answers 4

2 Comments

Comments

Comments

3 Comments

Your Answer

Hot Network Questions

Collectives™ on Stack Overflow

4 Answers 4

2 Comments

Comments

Comments

3 Comments

Your Answer

Sign up or log in

Post as a guest

Related