My array of objects only printing last entered value java

Question

Hi I am new to Java programming. Here I am trying to implement a code with array of objects. The problem is whenever I try to print. It only prints the last entered value 10 times.

import java.util.*;

class Tax{
    int ssn,income;
    void Tax(){}

    void Tax(int s,int i){
         this.ssn=s;this.income=i;      
    }

    int getssn(){
        return ssn;
    }

    int getincome(){
        return income;
    }
}

public class Usetaxpayer{
     public static void main(String[] args){
         Tax[] y=new  Tax[10];
         int i,inc,s=100;
         Scanner in=new Scanner(System.in);Tax x=new Tax();
         for(i=0;i<10;i++)
         {
             inc=in.nextInt();y[i]=x;
             x.Tax(s,inc);
             s++;      
         }
         for(i=0;i<10;i++)
         {
              System.out.println("SSN"+y[i].getssn()
              +"income"+y[i].getincome()+"\n");
         }
     }
}

Please help me out`

Answer 1

You've mistakenly put void for the constructor. Also, you need to create the instance inside the loop.

Demo:

import java.util.Scanner;

class Tax {
    int ssn, income;

    Tax(int s, int i) {
        this.ssn = s;
        this.income = i;
    }

    int getssn() {
        return ssn;
    }

    int getincome() {
        return income;
    }
}

public class Usetaxpayer {
    public static void main(String[] args) {
        final int SIZE = 2;
        Tax[] y = new Tax[SIZE];
        int i, inc = 0, s;
        Scanner in = new Scanner(System.in);
        for (i = 0; i < SIZE; i++) {
            System.out.print("Enter SSN: ");
            s = in.nextInt();
            System.out.print("Enter income: ");
            inc = in.nextInt();

            y[i] = new Tax(s, inc);
        }
        for (i = 0; i < SIZE; i++) {
            System.out.println("SSN: " + y[i].getssn() + ", income: " + y[i].getincome());
        }
    }
}

A sample run:

Enter SSN: 123
Enter income: 1000
Enter SSN: 234
Enter income: 2000
SSN: 123, income: 1000
SSN: 234, income: 2000

Note: I've used an array of size, 2 for demo. Change the value of SIZE as per your requirement.

Answer 2

The problem is you are using one object 10 times and replacing the values again and again. This is persisting only the last value. Try out this:

class Tax{

    int ssn,income;
    void Tax(){}

    void Tax(int s,int i){
        this.ssn=s;this.income=i;
    }

    int getssn(){
        return ssn;
    }

    int getincome(){
        return income;
    }
}

public class Main{
    public static void main(String[] args){
        Tax[] y=new  Tax[10];

        int i,inc,s=100;

        Scanner in=new Scanner(System.in);

        for(i=0;i<10;i++)
        {
            Tax x=new Tax();
            inc=in.nextInt();
            y[i]=x;
            x.Tax(s,inc);
            s++;
        }

        for(i=0;i<10;i++)
        {
            System.out.println("SSN "+y[i].getssn() +"income "+y[i].getincome()+"\n");
        }
    }
}

Answer 3

You have two errors:

1. Error when declaring the constructors these are declared without type as in the following code:

public Tax(){}

 public Tax(int s, int i){ this.ssn=s;this.income=i; }

the builders can be public or private according to your need.

2. At the moment going through your loop and adding to the array the object x is only adding the same memory instance, the best way to add is the following.

 Scanner in=new Scanner(System.in); for(i=0;i<10;i++) { inc= in.nextInt(); y[i]= new Tax(s,inc); s++; }

this way you always add a new Tax instance.