Null Pointer Exception when trying to add new object to array?

Question

I have an array, moviearray, with logical size of 15 and physical size of 50. I have the following code:

    for(int a=0;a<moviearray.length;a++)
            {
                if (moviearray[a]!=null)
                    {
                        if(moviearray[a].getTitle()==catAddTitle.getText())
                        {
                            moviearray[a].addExisting(Integer.parseInt(catAddNumber.getText()));
                            break;
                        }
                    }   
                else
                {
                    moviearray[a].setTitle(catAddTitle.getText());
                    moviearray[a].setNumber(Integer.parseInt(catAddNumber.getText()));
                    moviearray[a].setGenre(catAddGenre.getText());
                    moviearray[a].setYear(Integer.parseInt(catAddYear.getText()));
                    moviearray[a].setRating(catAddRating.getSelectedItem());
                    moviearray[a].setPrice(Double.parseDouble(catAddPrice.getText()));
                    break;
                }
            }

I am trying to have it so where when I enter a movie title into catAddTitle (text field), and it matches a movie currently in moviearray, it will increase the movie's amount element by the number entered in the textfield catAddNumber. However, when I try doing this, it gives me a nullpointerexception on the line:

    moviearray[a].setTitle(catAddTitle.getText());

Example: one of my objects in the array has the elements "Hobbit/55/Adventure/2012/PG-13/10.00" (title, number, genre, year, rating, price). What should happen is that when I enter "Hobbit" into catAddTitle and "3" into catAddNumber, it should change the number to "58" (despite the other textfield data). Thanks in Advance

By the way you should use .equals() to compare string rather than ==. The later will return false for two distinct instances of Strings with the same content whereas .equals() checks the content. — Pierre
– Pierre, Commented Mar 7, 2014 at 15:14

A4L · Accepted Answer · 2014-03-07 15:16:28Z

4

In your else-branch - which is executed only if moviearray[a] == null - you need to do

moviearray[a] = new YourObject();

first, i.e. create an instance of your class and store it in the array.

edited Mar 7, 2014 at 15:16

answered Mar 7, 2014 at 15:10

A4L

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1 Comment

Stanton Programmer Over a year ago

That fixed it. I keep forgetting that it doesn't automatically make empty objects. Thank you :).

Nambi · Accepted Answer · 2014-03-07 15:11:16Z

1

You need to compare the String with equals() not with == Operator

change this line with

if(moviearray[a].getTitle()==catAddTitle.getText())

to

if(moviearray[a].getTitle().equals(catAddTitle.getText()))

answered Mar 7, 2014 at 15:11

Nambi

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