java - Android:java TextView颜色

Question

我需要一点帮助。我需要用java代码改变 TextView 的颜色。我尝试了不同的方法，但它总是给我一个错误:

java.lang.NullPointerException

我尝试过:

TextView sts;
sts = (TextView) findViewById(R.id.stato);
sts.setTextColor(Color.rgb(12,255,0));

或者..

sts.setTextColor(android.graphics.Color.GREEN);

但双向开始时给我同样的错误..我的类扩展了 ListActivity

我该怎么办？提前致谢

完整代码:

public class ProvaDatabase extends ListActivity{

    TextView sts;   
    private DatabaseHelper databaseHelper;

    @Override
    public void onCreate(Bundle savedInstanceState)
    {
        sts = (TextView) findViewById(R.id.stato);
        sts.setTextColor(android.graphics.Color.GREEN);
        //sts.setTextColor(Color.rgb(12,255,0));

        super.onCreate(savedInstanceState);
        databaseHelper = new DatabaseHelper(this);
        SQLiteDatabase db = databaseHelper.getWritableDatabase();
        databaseHelper.insertdb(db, "sta", "25/11/2016", "SUCCESS", null, null, null);
        databaseHelper.insertdb(db, "ssis", "25/11/2016", "WAITING", null, null, null);
        databaseHelper.insertdb(db, "AAAAAAAA", "25/11/2016", "FAILED", null, null, null);
        databaseHelper.insertdb(db, "BBBB", "bBBBBBB", "SUCCESS", null, null, null);
        Cursor c = databaseHelper.getDB();
        startManagingCursor(c);
        setListAdapter(new SimpleCursorAdapter(this, R.layout.registryvista, c, new String[]
        { TabellaRegistry.TYPE, TabellaRegistry.DATE, TabellaRegistry.STATUS }, new int[]
        { R.id.tipo, R.id.data, R.id.stato }));


        setContentView(R.layout.main2);

Answer 1

似乎未找到您的 View R.id.stato，因此sts == null。尝试检查 sts 是否不为空，或者需要一些额外的代码

编辑:

如果您无法访问列表中项目的布局而不是做

setListAdapter(new SimpleCursorAdapter(this, R.layout.registryvista, c, new String[]
    { TabellaRegistry.TYPE, TabellaRegistry.DATE, TabellaRegistry.STATUS }, new int[]
    { R.id.tipo, R.id.data, R.id.stato }));

你可以像这样编写自己的适配器:

public class MyAdapter extends SimpleCursorAdapter
{
    //here goes methods that should be overriden

    //and method getView in which we can access layout of our list item
    @Override
    public View getView (int position, View convertView, ViewGroup parent)
    {
        View view = super.getView(postition, convertView, parent);
        TextView sts = (TextView) view.findViewById(R.id.stato);
        sts.setTextColor(android.graphics.Color.GREEN);
    }
}

希望你明白我的想法