ArrayAdapter returns a NullPointerException

Question

I am using a spinner that has data to be filled in by an Array Adapter. The code returns a run-time error caused by NullPointerException. I have declared the spinner and initialized it in on create method.The error still persists. Please help me solve the bug.

MainActivity.java

public class MainActivity extends AppCompatActivity implements View.OnClickListener
{

Button btnCfg, btnConnect, btnClear, btnUpload, btnDownload, btnLoad_on, btnLoad_off;
TextView txtSelectDayTitle;
Spinner spinnerDay;
private String[] arraySpinner;
private Context context;


@Override
protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.activity_main);

    //Automatic Day Picker
    String from = getIntent().getStringExtra("FROM");
    if (from != null && from.equals("DaysOfTheWeek"))
    {
        this.arraySpinner = new String[]{"Sunday", "Monday", "Tuesday", "Wednesday", "Thursday", "Friday", "Saturday"};

    }
    //Initialization of variables
    spinnerDay = (Spinner) findViewById(R.id.spinnerDay);
    btnCfg = (Button) findViewById(R.id.btnCfg);
    btnConnect = (Button) findViewById(R.id.btnConnect);
    btnClear = (Button) findViewById(R.id.btnClear);
    btnUpload = (Button) findViewById(R.id.btnUpload);
    btnDownload = (Button) findViewById(R.id.btnDownload);
    btnLoad_on = (Button) findViewById(R.id.btnLoad_on);
    btnLoad_off = (Button) findViewById(R.id.btnLoad_off);
    txtSelectDayTitle = findViewById(R.id.txtSelectDayTitle);


    SimpleDateFormat dayFormat = new SimpleDateFormat("EEEE");
    Date d = new Date();
    Calendar calendar = null;
    try
    {
        calendar = Calendar.getInstance();
        calendar.setTime(d);
    }
    catch (Exception e)
    {
        e.printStackTrace();
    }
    String dayOfTheWeek = dayFormat.format(d);
    txtSelectDayTitle.setText(dayOfTheWeek);

    ArrayAdapter<String> adapter = new ArrayAdapter<String>(this, android.R.layout.simple_spinner_item, arraySpinner);
    adapter.setDropDownViewResource(android.R.layout.simple_spinner_dropdown_item);
    spinnerDay.setAdapter(adapter);

Logcat:

Caused by: java.lang.NullPointerException
    at java.util.Objects.requireNonNull(Objects.java:203)
    at java.util.Arrays$ArrayList.<init>(Arrays.java:3741)
    at java.util.Arrays.asList(Arrays.java:3728)
    at android.widget.ArrayAdapter.<init>(ArrayAdapter.java:163)
    at com.example.itimer.MainActivity.onCreate(MainActivity.java:110)
    at android.app.Activity.performCreate(Activity.java:7023)
    at android.app.Activity.performCreate(Activity.java:7014)
    at android.app.Instrumentation.callActivityOnCreate(Instrumentation.java:1214)
    at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2758)

the exception stacktrace will show what is null in your code. Either check it yourself or post here. — Vladyslav Matviienko, Jul 15 '19 at 07:34
Possible duplicate of [What is a NullPointerException, and how do I fix it?](https://stackoverflow.com/questions/218384/what-is-a-nullpointerexception-and-how-do-i-fix-it) — Cà phê đen, Jul 15 '19 at 07:41
`if (from != null && from.equals("DaysOfTheWeek"))` check if this condition is `true`. `arraySpinner` only initialized if it is `true` — Vladyslav Matviienko, Jul 15 '19 at 07:41
`Analyze my Code and help me solve the bug.` this does not work that way on StackOverflow. If you want somebody to `Analyze my Code and help me solve the bug.`, you can hire a developer somewhere. Or you can *ask people here to help you fixing your code*. Please be more kind, and instead of giving orders like `Analyze my Code and help me solve the bug.` ask people to help. — Vladyslav Matviienko, Jul 15 '19 at 07:43

score 0 · Accepted Answer · answered Jul 15 '19 at 07:42

0

Check if this part of your code is getting initialized,

String from = getIntent().getStringExtra("FROM");
if (from != null && from.equals("DaysOfTheWeek"))
{
    this.arraySpinner = new String[]{"Sunday", "Monday", "Tuesday", "Wednesday", "Thursday", "Friday", "Saturday"};

}

Confirm if arraySpinner is not null. If it is null then this is causing that null pointer exception.

answered Jul 15 '19 at 07:42

Rohit J

107
7

1

Yah appears that is the issue. – fredrick mwenda Jul 16 '19 at 07:31

score 0 · Answer 2 · answered Jul 15 '19 at 08:21

The problem is simply because you have a null value of arraySpinner variable for the Adapter.

You should always initialize the array whenever you need to give it to your Adapter.

You can use one of the following options:

First option, always initialize the array:

String from = getIntent().getStringExtra("FROM");
if (from == null) {
  // initialize the array when found nothing
  arraySpinner = new String[];

} else if(from.equals("DaysOfTheWeek")) {
    arraySpinner = new String[]{"Sunday", "Monday", "Tuesday", "Wednesday", "Thursday", "Friday", "Saturday"};

} else {
  // initialize the array when incorrect from string found.
  arraySpinner = new String[];
}

Second option, crash the program when there is no from string:

String from = getIntent().getStringExtra("FROM");
if (from == null) {
  throw new RuntimeException("No extra found!");
  return;
}

// if incorrect from string found
if (!from.equals("DaysOfTheWeek")) {
  throw new RuntimeException("No DaysOfTheWeek found!");
  return;
}

 // correct extra for from is found.
 arraySpinner = new String[]{"Sunday", "Monday", "Tuesday", "Wednesday", "Thursday", "Friday", "Saturday"};

ArrayAdapter returns a NullPointerException

2 Answers2