android - 在 android 中以编程方式创建和添加 TextView

Question

我正在尝试以编程方式添加TextView到 may RelativeLayout。它不工作。

public class MainActivity extends Activity {

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);

        RelativeLayout rl = (RelativeLayout) findViewById(R.layout.activity_main);
        TextView tv = new TextView(MainActivity.this);

        tv.setText("Hello World");
        tv.setTextColor(Color.BLACK);
        tv.setLayoutParams(new LayoutParams(LayoutParams.MATCH_PARENT,LayoutParams.WRAP_CONTENT));
        rl.addView(tv);     
        setContentView(R.layout.activity_main);

    }

Answer 1

你应该setContentView(R.layout.activity_main)在之后打电话super.onCreate。

我这样做了：

1. 我去了 main_activity.xmlandroid:id="@+id/activity_main"并向RelativeLayout 添加了一个属性。

2. 编辑代码：

   @Override
   protected void onCreate(Bundle savedInstanceState) {
       super.onCreate(savedInstanceState);
       setContentView(R.layout.activity_main);
   
       //RelativeLayout rl = (RelativeLayout) findViewById(R.layout.activity_main);
       RelativeLayout rl = (RelativeLayout) findViewById(R.id.activity_main);
       TextView tv = new TextView(MainActivity.this);
   
       tv.setText("Hello World");
       tv.setTextColor(Color.BLACK);
       tv.setLayoutParams(new LayoutParams(LayoutParams.MATCH_PARENT,LayoutParams.WRAP_CONTENT));
       rl.addView(tv);     
   
   }
   

   但是，textView 仍然会与 RelativeView 上的其他生成项目重叠。也许您应该考虑使用具有垂直方向的 LinearLayout。

Answer 2

调用setContentView(R.layout.activity_main)将重新膨胀您的布局，覆盖您之前所做的添加。向上移动它，所以这是super通话后的第一件事。就像是：

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

    RelativeLayout rl = (RelativeLayout) findViewById(R.layout.activity_main);
    TextView tv = new TextView(MainActivity.this);

    tv.setText("Hello World");
    tv.setTextColor(Color.BLACK);
    tv.setLayoutParams(new LayoutParams(LayoutParams.MATCH_PARENT,LayoutParams.WRAP_CONTENT));
    rl.addView(tv);     
}