Question

This is a method I’m working on. It needs to return an Array[] of results or return null.
However, I’m getting a NullPointerException error when I attempt to test it. I’ve been searching and getting nowhere the past few hours. Any help for a suffering student would be appreciated.

public Item[] searchByName(String name) {

    String n = name;
    ArrayList<Item> sortName = new ArrayList<Item>();
    Item[] matchArr;
    boolean noResult = false;

    for(int j = 0; j < itemInventory.size(); j++){
        if(itemInventory.get(j).getName().equalsIgnoreCase(n) == true)
            sortName.add(itemInventory.get(j));
        else
            noResult = true;
    }
    matchArr = new Item[sortName.size()];
    for(int j = 0; j < sortName.size(); j++){
        matchArr[j] = sortName.get(j);
    }
    if(noResult == true)
        return null;

    else
        return matchArr;

}

//Revised version
//itemInventory is an ArrayList of objects being inventoried and sorted.

public Item[] searchByName(String name) {

    String n = name;
    ArrayList<Item> sortName = new ArrayList<Item>();
    Item[] matchName;

    for(int j = 0; j < itemInventory.size() ; j++){
        if(itemInventory.get(j) != null){
            if(itemInventory.get(j).getName().equalsIgnoreCase(n) == true){
                sortName.add(itemInventory.get(j));
                System.out.println(j + " Is a match");
            }
        }               
    }

    if(sortName.size() == 0)
        return null;
    else{
        matchName = sortName.toArray(new Item[sortName.size()]);
        return matchName;
    }

Answer 1

Probably this line itemInventory.get(j).getName().equalsIgnoreCase(n) == true causes NPE. Make sure that itemInventory.get(j) is not null before you get the name:

if(itemInventory.get(j)!=null) //only then get the name
    if(itemInventory.get(j).getName().equalsIgnoreCase(n))