需要帮助弄清楚为什么我不能使用自定义ArrayAdapter更改TextView文本

Question

I have a very simple app:

activity_main.xml

<RelativeLayout>
    <ListView android:id="@+id/emoticon_listview" />
</RelativeLayout>

item.xml

<TextView />

MainActivity.java

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

    int start = 0x1F004;
    int end = 0x1F65C;

    ListView listView = (ListView)findViewById(R.id.emoticon_listview);
    Integer[] emoticon_array = new Integer[end - start]

    for(int codepoint=start, i=0; codepoint<end; codepoint++, i++){
        emoticon_array[i] = codepoint;
    }

    CustomArrayAdapter customArrayAdapter = new CustomArrayAdapter(this, R.layout.item, emoticon_array);
    listView.setAdapter(customArrayAdapter);
}

CustomArrayAdapter.java

public class CustomArrayAdapter extends ArrayAdapter {
    public customArrayAdapter(Context context, int resource, Object[] objects){
        super(context, resource, objects);
    }

    @Override
    public View getView(int position, View convertView, ViewGroup parent){
        TextView textView = (TextView) convertView;

        if(textView != null){
            textView.setText(new String(Characters.toChars(Integer.parseInt(textView.getText().toString))));
            // -or-
            textView.setText("Hello, world!");
            // -or-
            textView.setText("whatever ...");
        }
    }

    return super.getView(position, convertView, parent);
}

The problem is that no matter what I put in the textView.setText() of the overridden getView() of my CustomArrayAdapter it always displays what is in the original emoticon_array.

I even tried this:

return super.getView(position, textView, parent);

But that didn't do anything either.

What am I doing wrong?

Thanks :)

Answer 1

You are using a custom layout R.layout.item so

• You need to inflate that layout in getview

• find your views(TextView) and apply changes then return that view

   @Override public View getView(int position, View convertView, ViewGroup parent){ TextView textView; if(convertView == null){ convertView = LayoutInflater.from(getContext()).inflate(R.layout.item,parent,false); // to reuse view next time } // find your text view textView = (TextView)convertView.findViewById(R.id.yourTextViewID); textView.setText(getItem(position).toString()); //textView.setText("Hello, world!"); // -or- //textView.setText("whatever ..."); // return inflated view return convertView; } 

Note : Don't use Object array and use getItem to fetch the item using position to display the item from array

Answer 2

You should call super.getView() at the beginning of your own getView() method:

@Override
public View getView(int position, View convertView, ViewGroup parent){
    TextView textView = (TextView) super.getView(position, convertView, parent);
    textView.setText("Hello, world!");
    // -or-
    textView.setText("whatever ...");

    return textView;
}

This allows you to take advantage of the logic to recycle convertView if it is not null . Then you can make whatever changes you wish and return the resulting view directly.

Note that I have removed this line:

    textView.setText(new String(Characters.toChars(Integer.parseInt(textView.getText().toString))));

First of all, it is missing a pair parentheses which causes a compiler error. More importantly, this does a lot of work for not visible benefit. The end result is either an error, if the original text is not numerical, or setting the text back to the original value.