Question

I have created this simple android Activity to demonstrate my problem.

I just want the screen to have a textInput, and a button. Below these two, I want to create a ListView if the button is pressed (The button basically calls some method and gets an array of String. I want the ListView to display this array.

So its a plain Screen, a button, a text input, when button pressed it calls a method and receives an array of string and want to Print the list underneath them.

public class TagListViewer  extends ListActivity {

    private Button clickBtn;
    EditText textInput;
    String[] resultStr = {"a", "b", "c"}; //Ideally would want this inside the button OnClickListener... but couldn't bcz I needed one for the Array adapter.

    @Override
    public void onCreate(Bundle savedInstanceState) {

        super.onCreate(savedInstanceState);
        setContentView(R.layout.tagselection);

        clickBtn = (Button) findViewById(R.id.CreatePL);
        clickBtn.setText("Search");
        textInput = (EditText) findViewById(R.id.textInput);

        ArrayAdapter<String> adapter = new ArrayAdapter<String>(this,android.R.layout.simple_list_item_1, resultStr);
        setListAdapter(adapter);

        clickBtn.setOnClickListener(new OnClickListener() {

            public void onClick(View v) {

                ArrayAdapter<String> adapter = (ArrayAdapter<String>) getListAdapter();

                adapter.add("ABC"); //This I could use the array I get to add its elements
                adapter.notifyDataSetChanged();
            }

        });
    }
}

Answer 1

I’m not certain what your question is, but I noticed that you are trying to add items to a primitive String array and creating two different adapters… I have a hunch about the problem. Look at the simple changes below:

public class TagListViewer  extends ListActivity {
    // Make adapter a class variable
    private ArrayAdapter<String> adapter;

    private Button clickBtn;
    EditText textInput;

    // You cannot add items to a primitive String array, we'll convert this to an ArrayList
    String[] resultStr = {"a", "b", "c"}; 
    List<String> list = new ArrayList<String>();

    @Override
    public void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.tagselection);

        // Add contents of resultStr to the dynamic List
        Collections.addAll(list, resultStr);

        clickBtn = (Button) findViewById(R.id.CreatePL);
        clickBtn.setText("Search");
        textInput = (EditText) findViewById(R.id.textInput);

        // Reflect class variable change and use list instead of resultStr
        adapter = new ArrayAdapter<String>(this,android.R.layout.simple_list_item_1, list);
        setListAdapter(adapter);

        clickBtn.setOnClickListener(new OnClickListener() {
            public void onClick(View v) {
                // This will add the one phrase "ABC"
                //adapter.add("ABC");

                // This will add the contents of textInput
                adapter.add(textInput.getText().toString());
            }
        });
    }
}

Added from comments

A ListActivity is required to have a ListView with the id android.R.id.list in its layout:

<ListView android:id="@android:id/list"
        android:layout_width="fill_parent"
        android:layout_height="fill_parent"/>