How to declare an array element null?

Question

I am trying to find out whats happening with my code, I kept getting nullexeptionpointer problem. So I decided to reduce my code and find out whats happening. I want to remove a particular element providing the index to be removed, afterwards, moving all element after it to fill up the space left.

After moving all element, I want to set the last element in the array to null, but i get error and wont compile.

public static void main(String[] args) {


    int [] charSort = new int[] {12, 5, 7, 4 ,26 ,20 ,1, 6 ,3 ,14, 8, 11};

    TextIO.putln("ArrayNum = [12, 5, 7, 4 ,26 ,20 ,1, 6 ,3 ,14, 8, 11]\n");

    TextIO.put("Sorted ArrayNum is:  \n");

    //IntSelecttionSort(charSort);

    TextIO.putln(Arrays.toString(charSort));

    TextIO.put("Enter: "); RemoveShift (charSort, TextIO.getInt());
}


public static void RemoveShift (int[] move, int p){

    for(int i = 0; i<move.length; i++){

        TextIO.put(i+", ");
    }
    TextIO.putln();
    for(int i = p; i<move.length-1; i++){

        move[i]=move[i+1];
    }
    move[move.length-1]=null; // null seems not to work here

    TextIO.putln(Arrays.toString(move));
}

Keppil · Accepted Answer · 2014-01-12 17:38:17Z

5

int is a primitive, and can't be assigned the value null.

If you want to use null here, you can use the wrapper class Integer instead:

public static void RemoveShift (Integer[] move, int p){

Because of autoboxing, you can even initialize your array in the same way:

Integer[] charSort = new Integer[] {12, 5, 7, 4 ,26 ,20 ,1, 6 ,3 ,14, 8, 11};

As @JBNizet points out, a nice alternative if you want to modify an array of Integer is to use an ArrayList instead. That can make your life much easier.

edited Jan 12, 2014 at 17:38

answered Jan 12, 2014 at 17:28

Keppil

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1 Comment

JB Nizet Over a year ago

If a modifiable array of Integer is what the OP wants, then he should use an ArrayList instead of reinventing the wheel. Not a critique of your answer, just worth mentioning, IMO.

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