请帮我在android中的自定义布局

Question

java.lang.RuntimeException: Unable to start activity `ComponentInfo{com.example.demo/com.example.demo.Demo}: android.view.InflateException: Binary XML file line #7: Error inflating class com.example.component.MainActivity`

 public class MainActivity extends FrameLayout { public MainActivity(Context context) { super(context); // TODO Auto-generated constructor stub } } 

activity_main.xml

<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:tools="http://schemas.android.com/tools"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    tools:context=".MainActivity" >

    <TextView
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:layout_centerHorizontal="true"
        android:layout_centerVertical="true"
        android:text="@string/hello_world" />

</RelativeLayout>

Demo.java

public class Demo extends Activity {

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


}

activity_demo.xml

<FrameLayout xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:tools="http://schemas.android.com/tools"
    android:layout_width="fill_parent"
    android:layout_height="fill_parent"
 >

  <com.example.component.MainActivity
    android:id="@+id/comp"
    android:layout_width="fill_parent"
    android:layout_height="fill_parent"
      />
</FrameLayout>

Answer 1

You can't put an activity in a layout. Only views or view groups.

Answer 2

The inflator uses the two argument constructor when it creates an instance of your view class. You must provide

public MainActivity(Context context, AttributeSet attrs) {
    super(context, attrs);
    // TODO Auto-generated constructor stub
}

Answer 3

Since Demo is your Activity, define it in Android manifest.xml file using the package name: com.example.demo.Demo. And why are you adding framelayout inside frameLayout use only one , your custom framelayout. and define the xml as:

<com.example.component.MainActivity
    xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:tools="http://schemas.android.com/tools"
    android:id="@+id/comp"
    android:layout_width="fill_parent"
    android:layout_height="fill_parent"
 />

//hope it works