Delete array element - move all elements down one index

Question

I have code which allows a user to delete an element from an array that they select however I then want to move all existing elements "down one" so there are no gaps left in the array.

At the moment if I delete the first element (index 0) it is deleted but if I add information to the array it is entered at index 1 and index 0 is left null. If something is deleted from an index which has information in the following indices how can I move all the information down one index?

My delete method:

  static void deleteStudent() {
    System.out.println("Wish student would you like to delete?");
    for(int i=0;i<9;i++) {
      System.out.println(i + ": " + studentNamesArray[i]);
    }
    int studentChoice = input.nextInt();
    for(int i = studentChoice+1; i<studentNamesArray.length; i++) {
      studentNamesArray[i-1] = studentNamesArray[i];
    }
  }

EDIT:

I added four entries to the array: [one, two, three, four, null, null, null, null, null, null]

I ran then program and tried to delete index [2], this was successful outputting the following: [one, two, four, null, null, null, null, null, null, null]

as you can see the the elements where moved down as wanted, the problem is then when I add a value to the array again the deleted index is passed over and the element is entered into the next index, see below: [one, two, four, null, newadd, null, null, null, null, null]

How can I have the program entering the new value into the correct array?

Add method:

  static void addStudent() {
    if (nameArrayCount < 10) {
      System.out.println("Enter the student's name in the following format - surname, forename: ");
      studentName = input.next();
      studentNamesArray[nameArrayCount] = studentName;
      nameArrayCount = nameArrayCount + 1;
    }
    else if (nameArrayCount == 10) {
      System.out.println("******Array is full, please delete a student before adding another.*****");
    }
    if (markArrayCount < 10){
    System.out.println("Enter the first mark: ");
          markOne = input.nextInt();
          System.out.println("Enter the second mark: ");
          markTwo = input.nextInt();
          System.out.println("Enter the third mark: ");
          markThree = input.nextInt();
          studentMarksArray[markArrayCount][0] = markOne;
          studentMarksArray[markArrayCount][1] = markTwo;
          studentMarksArray[markArrayCount][2] = markThree;
          markArrayCount = markArrayCount + 1;
    }
  }

Answer 1

I rewrote your code but added a temp array that stores all of the values except for the deleted element in the first index position onward. This should delete the element and shift the array to the left-most position with the right-most position left as null.

static void deleteStudent() {
    System.out.println("Which student would you like to delete?"); //fixed spelling error
    for(int i=0;i<9;i++) {
      System.out.println(i + ": " + studentNamesArray[i]);
    }
    int studentChoice = input.nextInt();
    StudentName[] temp = new StudentName[studentNamesArray.length];//I don't know format
    for(int i = 0; i<studentNamesArray.length; i++) {
        if(i != studentChoice)
        {
            temp[j] = studentNamesArray[i]
            j++;
        }
    }
    temp[studentNamesArray.length-1] = null;
    studentNamesArray = temp;
}