android - 如何更改特定 ListView 的项目或元素的颜色

Question

我有一个 ListView，它由一个字符串数组扩充。在 ListView 的顶部，我添加了一个按钮，我希望每当用户单击该按钮时，4 个项目的颜色会自动更改。

这是我的 Activity 代码:

    public class MainActivity extends Activity
    {
    String[] countryNames = {"Germany", "France", "Italy", "Spain", "Russia", "USA", "Iran", "China", "Inida"};
    Button button;
    ListView listView;

    /**
     * Called when the activity is first created.
     */
    @Override
    public void onCreate(Bundle savedInstanceState)
    {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.listview);

        button = (Button) findViewById(R.id.button_changeColor);

        ListViewAdapter adapter = new ListViewAdapter(getApplicationContext());//
        listView = (ListView) findViewById(R.id.listView_1);//
        listView.setAdapter(adapter);//


        button.setOnClickListener(new View.OnClickListener()
        {
            @Override
            public void onClick(View v)
            {
                // here i want to change the the color 4th item.
            }
        });


    }


    private class ListViewAdapter extends BaseAdapter
    {
        LayoutInflater layoutInflater;

        public ListViewAdapter(Context context)
        {
            layoutInflater = (LayoutInflater) getSystemService(Context.LAYOUT_INFLATER_SERVICE);
        }

        @Override
        public int getCount()
        {
            return countryNames.length;
        }

        @Override
        public Object getItem(int position)
        {
            return null;
        }

        @Override
        public long getItemId(int position)
        {
            return 0;
        }

        @Override
        public View getView(final int position, View convertView, ViewGroup parent)
        {

            ViewHolder viewHolder;
            if (convertView == null)
            {
                convertView = layoutInflater.inflate(R.layout.listview_template, null);

                viewHolder = new ViewHolder();
                viewHolder.addedTextView = (TextView) convertView.findViewById(R.id.textView_Template);
                convertView.setTag(viewHolder);
            } else
            {
                viewHolder = (ViewHolder) convertView.getTag();
            }

            viewHolder.addedTextView.setText(countryNames[position]);

            return convertView;
        }
    }

    private class ViewHolder
    {
        TextView addedTextView;
    }
}

还有我的 listview.xml 文件:

<?xml version="1.0" encoding="utf-8"?>

<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
              android:orientation="vertical"
              android:layout_width="match_parent"
              android:layout_height="match_parent">

    <Button
            android:layout_gravity="center"
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"
            android:text="Change Color"
            android:id="@+id/button_changeColor"/>
    <ListView
            android:layout_width="wrap_content"
            android:layout_height="300dp"
            android:id="@+id/listView_1">
    </ListView>
</LinearLayout>

最后是 listview_template.xml:

<?xml version="1.0" encoding="utf-8"?>

<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
              android:orientation="vertical"
              android:layout_width="match_parent"
              android:layout_height="match_parent">

    <TextView
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"
            android:id="@+id/textView_Template"
            />
</LinearLayout>

所以我的问题是，如何通过单击按钮更改特定项目的颜色。

Answer 1

像那样吗？

    listView.getChildAt( 4 );
    View item_4 = listView.getChildAt(4);
    item_4.setBackgroundResource( <new_background> );
    ( (TextView) item_4.findViewById( R.id.text1 ) ).setTextColor( <new_font_color> );

如果你需要改变所有的项目，你可以使用带有迭代器的cicle或者像这样的简单的For:

for(int i=0;i<listView.getChildCount();i++) {
  View item = listView.getChildAt(i);
  // some yours code
}