How to check if array indexes are empty and if so check the next?

Question

Anybody got any idea on how I can check if an array indexes(not just one index) are empty and if is empty or zero put a value there. And also if all the indexes are all not empty print an error.

Sorry unfortunately I can't give rep.

import java.util.Scanner; 
public class Myhash {
/**
 * @param args
 */
public static void main(String[] args) {
 // TODO Auto-generated method stub
 int [] myData = new int[17]; 
 int [] newData = new int [17];
 System.out.println("Please enter 16 integer numbers");
 for(int i= 0; i<myData.length; i++){
 //System.out.print("Please enter 16 numbers");
 Scanner input = new Scanner(System.in);
 int data =input.nextInt(); 
 myData[i]=data; 
 int num3 = data % 17;
 newData[num3]=data; 
 } 
 System.out.println("These are the numbers you entered\n"); 
 System.out.printf("%s%8s \n", "Index", "Value"); 
 for(int t=0; t<myData.length; t++){
 System.out.printf("%5d%8d\n", t, myData[t]);
 }
 System.out.println("\n");
 System.out.println("The Hash Function:\n\n");
 System.out.printf("%5s%8s \n", "Index", "Value"); 
 for(int s=0; s<newData.length; s++){
 System.out.printf("%5d%8d\n", s, newData[s]);
 } 
 }
}

on here:

 for(int s=0; s<newData.length; s++){
 System.out.printf("%5d%8d\n", s, newData[s]);
 }

how do check for more than one index(if empty? If the index is empty how do check for the next index and if that one is not empty how do i check the next one, etc?

• ianaldo21: Also, what is the array storing? Strings, integers etc?
• user1244123: in java is an int. I only know how to check for one index
• Hot Licks: Uh, what does it mean for an index to be "empty"???
• Andrzej Jozwik: arrays of int by default has all zero values. So if element is zero it has not been set or it has been set to zero :)
• user1244123: I can't figure this out: If the index is empty how do check for the next index and if that one is not empty how do i check the next one, etc? as ajozwik said, if is zero then is considered empty because is an int

Answer 1

Elements in primitive arrays can't be empty. They'll always get initialized to something

If you declare the array like so

 int [] newData = new int [17];

then all of the elements will default to zero.

For checking if an element is not entered, you can use a simple loop :

 for(int i=0;i<newData.length;i++)
 {
 if(newData[i]==0)
 System.out.println("The value at " + i + "is empty");
 }

Although , the above code will not work in your case, because the user might enter 0 as an input value and still this code will consider it to be empty.

What you can do is, initialize the array with all values as -1, and specify at the input prompt that only values>=0 can be entered . The initialization can be done like this:

int[] newData = new int[17];
for(int i=0;i<newData.length;i++)
{
 newData[i]= -1; 
}

Then you can ask the user for input and do the processing. Then you can use this:

for(int i=0;i<newData.length;i++)
 {
 if(newData[i]==-1)
 System.out.println("The value at " + i + "is empty");
 }

Answer 2

Here:

for(int i = 0; i < array.length; i++)
{
 if(array[i] == null)
 continue;
}

• Wulf: You have to explain more. This is basically a code-only answer.