Android: getting Null Pointer Exception when inserting in Array

Question

I'm getting the error "java.lang.NullPointerException: Attempt to write to null array" when, after getting some data from database I have to put that data in a ArrayAdapter.

DatabaseHelper databaseHelper = new DatabaseHelper(this.getApplicationContext());

        List <Gasto> gastos;
        gastos = databaseHelper.getAllGastos();

        Gasto[] items=null;

        for(int i=0;i<gastos.size();i++)
        {
            items[i] = new Gasto(gastos.get(i).getMes(),gastos.get(i).getAno(), gastos.get(i).getDespesa_final());

        }

dataAdapter = new ArrayAdapter<Gasto>(this,android.R.layout.simple_list_item_1, items);

Can you please tell me how can I solve this error?

You have this line of code "Gasto[] items = null;" which surely causes a NPE. — harism
– harism, Commented Feb 23, 2015 at 19:54

Blackbelt · Accepted Answer · 2015-02-23 19:55:42Z

6

Gasto[] items=null;

you have to create the array of Gastos before accessing it:

Gasto[] items = new Gastos[gastos.size()];

answered Feb 23, 2015 at 19:55

Blackbelt

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2 Comments

porthfind Over a year ago

I do know it, but if I do what you said, I can't do this "items[i] = new Gasto(gastos.get(i).getMes(),gastos.get(i).getAno(), gastos.get(i).getDespesa_final());"

Blackbelt Over a year ago

why you can't? What I wrote allocates memory for the array. what you wrote create the object you want to store into the array. Both are needed.

dpassy · Accepted Answer · 2015-02-23 19:55:38Z

2

Gasto[] items = null; is the problem. Array is not created when you insert to it. Use Gasto[] items = new Gasto[gastos.size()];

answered Feb 23, 2015 at 19:55

dpassy

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