Java Inserting numbers into an array in order

Question

I am having problems with an assignment. I'm fairly new to coding and I am having a hard time trying to figure out how to do this. My professor supplied code for adding and removing items from an array but he wants us to add a method that would add items to the array in the correct position. This is the supplied code:

import java.util.*;

public class MyArrayList {
private Object[]buffer;
private int currentSize;

public MyArrayList(){
   final int INITIAL_SIZE=10;
  buffer = new Object[INITIAL_SIZE];
  currentSize=0;
  }

public int size() {
  return currentSize;
  }

private void checkBounds(int n){
  if (n<0||n>= currentSize){
     throw new IndexOutOfBoundsException();
     }
  }
public Object get (int pos){
  checkBounds(pos);
  return buffer[pos];
  }
public Object remove(int pos){
  checkBounds(pos);
  Object removed = buffer[pos];
  for (int i = pos+1; i < currentSize; i++){
     buffer[i-1] = buffer[i];
  }
  currentSize--;
  return removed;
}
public boolean add(int pos, Object newElement){
  growBufferIfNecessary();
  currentSize++;
  checkBounds(pos);
  for(int i = currentSize - 1; i > pos; i--){
     buffer[i] = buffer [i-1];
  }
  buffer[pos] = newElement;
  return true;
}
public boolean addLast(Object newElement){
  growBufferIfNecessary();
  currentSize++;
  buffer[currentSize -1] = newElement;
  return true;
}
 private void growBufferIfNecessary(){
  if (currentSize==buffer.length){
     Object[] newBuffer = new Object[2*buffer.length];
     for(int i=0; i<buffer.length; i++){
     newBuffer[i] = buffer[i];
     }
  buffer = newBuffer;
   }
} 

}

This is our assignment:

Add a method called "public void insert(int n)" that will add n to your MyArrayList object in the correct position maintaining the sorted order. Use your existing MyArrayList class with necessary modification.Here is a test case:

MyArrayList list = new MyArrayLst();

list.insert(5); insert(10); insert(8); insert(20); insert(6);

If you print the list now, it should print as:

5

6

8

10

20

So this is what I have so far in my main method:

 import java.util.*;

 public class ArrayListHomework {
 public static void main (String[]args){
 MyArrayList list = new MyArrayList();

 list.insert(5);
 list.insert(10);
 list.insert(8);
 list.insert(20);
 list.insert(6);
 for (int i=0; i<list.size(); i++){

     System.out.println(list.get(i));

   }
  }  
 }

I am super lost as to how to start this insert method. Any help would be appreciated. Thanks.

Answer 1

Thank you everyone for your help and suggestions. I got it to work by using the code that Marco13 suggested: https://codereview.stackexchange.com/questions/36221/binary-search-for-inserting-in-array#answer-36239 Hope everyone has a great day and happy programming. -TJ