check if array is alrdeady FULLY filled with any non-default value-CodePudding

I am not sure if it's rly possible to check but I have an issue rn where I have an array

let's say: int[] unmarkedSum = new int[100];

Now I put something in this array when a certain condition is true so not in every single iteration. But I know for a fact that at some point the whole array will be filled with any positive values that are not 0 because of how my algorithm works.

My question here is: Is there a way of checking WHEN it's fully filled?

Like I started like this:

for(int i = 0; i < unmarkedSum.length; i  ){
if(unmarkedSum[i] == 0{
break; //
}
else{
// idk tbh 
}
}

CodePudding user response：

In Java by default an array of ints is filled with zeros. You can use this to check if the array is fully filled. For example you can create a method which checks for 0 and returns true if there are no 0:

public static bool isArrayFilled(int[] array) {
    for(int i = array.length; i >= 0; i--){
        if(array[i] == 0) {
            return false;
        }
     }
     return true;
}

If array is big enough and filled out of order, you can use advanced algorithms to find at least one 0 value in the array.

CodePudding user response：

Per my previous comment, you can share this array with another thread so that one thread can fill the values and another can check the array at the same time. When the second thread finds that there are no default values (or 0s) then it can notify the first thread (or the main thread). Here is how you can do that

import java.util.Arrays;
import java.util.Random;

public class CheckArray {

    public static void main(String[] args) throws InterruptedException {
        var arr = new int[50];

        Thread arrayChecker = new Thread(() -> {
            var isZeroPresent = false;
            while (true) {
                for (int index = 0; index < arr.length; index  ) {
                    isZeroPresent = false;
                    if (arr[index] == 0) {
                        isZeroPresent = true;
                        break;
                    }
                }
                if (isZeroPresent == false) {

                    // if the for loop completed then control will come here
                    System.out.println("Array has been filled");
                    System.out.println(Arrays.toString(arr));
                    System.exit(0);
                }
            }
        });
        arrayChecker.start();
        
        // fill random values in the array
        // while another thread has been started
        Random random = new Random(); 
        while(true) {
            Thread.sleep(500);
            
            int index = random.nextInt(arr.length);
            arr[index] = random.nextInt(100);
            System.out.println(Arrays.toString(arr));
        }
        
    }


}