Android Studio-Spinner-获取Spinner项不起作用

Question

i tryed for hours to get the item out of my Spinner-Object but i always get the first item out of the Spinner Array. The array is defined in the string.xml. Is this mistake caused by the different contexts? When i only use the getSelectedItem command, i get a NullPointer Reference

 String taskName;
 String taskTag;
 Spinner spinner;
 ArrayAdapter<CharSequence> adapter;


 public void newTaskName() {

    final AlertDialog.Builder taskBuilder = new AlertDialog.Builder( MainActivity.this );
    final View bView = getLayoutInflater().inflate( R.layout.dialog_taskname, null );
    final EditText bTaskName = (EditText) bView.findViewById( R.id.taskNameEditText );
    Button buttonAdd = (Button) bView.findViewById( R.id.buttonAdd );
    Button buttonBack = (Button) bView.findViewById( R.id.buttonBack );


    taskBuilder.setView( bView );
    final AlertDialog dialog = taskBuilder.create();
    dialog.show();

    buttonAdd.setOnClickListener( new View.OnClickListener() {
        @Override
        public void onClick(View v) {
            if (!bTaskName.getText().toString().isEmpty()) {

                taskName = bTaskName.getText().toString();
                taskTag = (String) spinner.getSelectedItem();
                dialog.dismiss();
                System.out.println("Das ist der Tag: "+ taskTag);
                newTask( taskName, taskTag );

            } else {
              (...)

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

    spinner = (Spinner) findViewById( R.id.spinner_WT );
    adapter = ArrayAdapter.createFromResource( this, R.array.array_wochentage, android.R.layout.simple_spinner_item );
    adapter.setDropDownViewResource( android.R.layout.simple_spinner_dropdown_item );
    spinner.setAdapter( adapter );

    spinner.setOnItemSelectedListener( new AdapterView.OnItemSelectedListener() {
        @Override
        public void onItemSelected(AdapterView<?> parent, View view, int position, long id) {
            Object item = spinner.getItemAtPosition(position);

        }

        @Override
        public void onNothingSelected(AdapterView<?> parent) {
        }
    } );



            setContentView( R.layout.activity_main );
                    (...)

Answer 1

Instead of this line:

Object item = spinner.getItemAtPosition(position);

Try using this one:

Object item = parent.getItemAtPosition(position)

Also, did you add below lines in your code?

 Spinner spinner = (Spinner) findViewById(R.id.spinner);
 spinner.setOnItemSelectedListener(this);