Android：爲什麼TextField不顯示？

Question

TextView t = new TextView(this); 
    t.setX(0); 
    t.setY(0); 
    t.setText("Tap"); 
    t.setTextColor(Color.GREEN); 
    t.setTextSize(25); 
    t.setLayoutParams(new FrameLayout.LayoutParams(100, 100)); 
    setContentView(t); 

我在ActionBarActivity中，爲什麼我使用「this」作爲上下文，無法理解爲什麼textField沒有顯示，這裏是錯誤的嗎？

Answer 1

試試這個

TextView t= new TextView(this); 
    t.setX(0); 
    t.setY(0); 
    t.setText("Tap"); 
    t.setTextColor(Color.GREEN); 
    t.setTextSize(25); 
    addContentView(t, new FrameLayout.LayoutParams(100, 100)); 

Answer 2

創建XML文件

<FrameLayout xmlns:android="http://schemas.android.com/apk/res/android" 
    xmlns:tools="http://schemas.android.com/tools" 
    android:id="@+id/frame_layout" 
    android:layout_width="match_parent" 
    android:layout_height="match_parent" 
    android:paddingBottom="@dimen/activity_vertical_margin" 
    android:paddingLeft="@dimen/activity_horizontal_margin" 
    android:paddingRight="@dimen/activity_horizontal_margin" 
    android:paddingTop="@dimen/activity_vertical_margin" 
    tools:context="in.appkart.flashlight.MainActivity" > 

</FrameLayout> 

和MainActivity

package in.appkart.flashlight; 

import android.graphics.Color; 
import android.os.Bundle; 
import android.support.v7.app.ActionBarActivity; 
import android.view.View; 
import android.widget.FrameLayout; 
import android.widget.FrameLayout.LayoutParams; 
import android.widget.TextView; 

public class MainActivity extends ActionBarActivity { 

    private static final String TAG = MainActivity.class.getSimpleName(); 

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

     View frameLayout = findViewById(R.id.frame_layout); 

     TextView t = new TextView(this); 

     t.setX(0); 
     t.setY(0); 
     t.setText("Tap"); 
     t.setTextColor(Color.GREEN); 
     t.setTextSize(25); 
     t.setLayoutParams(new FrameLayout.LayoutParams(100, 100)); 
     t.setLayoutParams(new LayoutParams(LayoutParams.MATCH_PARENT, 
       LayoutParams.WRAP_CONTENT)); 

     ((FrameLayout) frameLayout).addView(t); 
    } 
}