android：将微调框绑定到自定义列表

Question

I am trying to display a Spinner list for user to select, then take the selection to bind to another array . The user-selected value surfaceCode is saved for later use. The Spinner array R.array.surface_option and the array to bind R.array.surface_code are aligned and saved in xml.

This is my code...

spinnerSurface = (Spinner) findViewById(R.id.spinnerSurface);
ArrayAdapter<CharSequence> adapterSurface = ArrayAdapter.createFromResource(this, R.array.surface_option, android.R.layout.simple_spinner_item);
adapterSurface.setDropDownViewResource(android.R.layout.simple_spinner_dropdown_item);
spinnerSurface.setAdapter(adapterSurface);

spinnerSurface.setOnItemSelectedListener(new Spinner.OnItemSelectedListener() { 
    public void onItemSelected(AdapterView<?> parent, View v, int position, long id) { 
        TextView tx = (TextView)v; 
        Log.i("\n\nid",String.valueOf(tx.getText()));
        String surfaceCode = getResources().getStringArray(R.array.surface_code)[spinnerSurface.getSelectedItemPosition()];
    }

    public void onNothingSelected(AdapterView<?> arg0) {
    } 
});

Log.d("code outside", surfaceCode.trim() + " is equal to SW: " + surfaceCode.trim().equals("SW"));

The surfaceCode comes out as error process stopped unexpectedly , probably because it returns null . What's wrong with my code?

Answer 1

surfaceCode can be null in the last code line because the code in the anonymous listener is only executed when the selection is made.

This would cause a NullPointerException in the last line.

Even if onItemSelected() is called, it will not set the member surfaceCode because you have declared a local variable of the same name that is shadowing it.

You should remove the "String " before the surfaceCode and put the log statement inside onItemSelected().