Android 在片段中添加画布时发生异常

我想把画布放在一块碎片里。不知道为什么它不起作用。我得到以下例外情况：

03-12 15:51:36.352    1911-1911/com.example.asif.test E/AndroidRuntime﹕ FATAL EXCEPTION: main
    Process: com.example.asif.test, PID: 1911
    java.lang.RuntimeException: Unable to start activity ComponentInfo{com.example.asif.test/com.example.asif.test.MainActivity}: android.view.InflateException: Binary XML file line #7: Error inflating class fragment
            at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2298)
            at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2360)
            at android.app.ActivityThread.handleRelaunchActivity(ActivityThread.java:3912)
            at android.app.ActivityThread.access$900(ActivityThread.java:144)
            at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1284)
            at android.os.Handler.dispatchMessage(Handler.java:102)
            at android.os.Looper.loop(Looper.java:135)
            at android.app.ActivityThread.main(ActivityThread.java:5221)
            at java.lang.reflect.Method.invoke(Native Method)
            at java.lang.reflect.Method.invoke(Method.java:372)
            at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:899)
            at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:694)
     Caused by: android.view.InflateException: Binary XML file line #7: Error inflating class fragment
            at android.view.LayoutInflater.createViewFromTag(LayoutInflater.java:763)
            at android.view.LayoutInflater.rInflate(LayoutInflater.java:806)
            at android.view.LayoutInflater.inflate(LayoutInflater.java:504)
            at android.view.LayoutInflater.inflate(LayoutInflater.java:414)
            at android.view.LayoutInflater.inflate(LayoutInflater.java:365)
            at com.android.internal.policy.impl.PhoneWindow.setContentView(PhoneWindow.java:377)
            at android.app.Activity.setContentView(Activity.java:2144)
            at com.example.asif.test.MainActivity.onCreate(MainActivity.java:19)
            at android.app.Activity.performCreate(Activity.java:5933)
            at android.app.Instrumentation.callActivityOnCreate(Instrumentation.java:1105)
            at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2251)
            at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2360)
            at android.app.ActivityThread.handleRelaunchActivity(ActivityThread.java:3912)
            at android.app.ActivityThread.access$900(ActivityThread.java:144)
            at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1284)
            at android.os.Handler.dispatchMessage(Handler.java:102)
            at android.os.Looper.loop(Looper.java:135)
            at android.app.ActivityThread.main(ActivityThread.java:5221)
            at java.lang.reflect.Method.invoke(Native Method)
            at java.lang.reflect.Method.invoke(Method.java:372)
            at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:899)
            at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:694)
     Caused by: java.lang.IllegalStateException: Fragment com.example.asif.test.FragmentOne did not create a view.
            at android.app.FragmentManagerImpl.onCreateView(FragmentManager.java:2145)
            at android.app.Activity.onCreateView(Activity.java:5282)
            at android.view.LayoutInflater.createViewFromTag(LayoutInflater.java:733)
            at android.view.LayoutInflater.rInflate(LayoutInflater.java:806)
            at android.view.LayoutInflater.inflate(LayoutInflater.java:504)
            at android.view.LayoutInflater.inflate(LayoutInflater.java:414)
            at android.view.LayoutInflater.inflate(LayoutInflater.java:365)
            at com.android.internal.policy.impl.PhoneWindow.setContentView(PhoneWindow.java:377)
            at android.app.Activity.setContentView(Activity.java:2144)
            at com.example.asif.test.MainActivity.onCreate(MainActivity.java:19)
            at android.app.Activity.performCreate(Activity.java:5933)
            at android.app.Instrumentation.callActivityOnCreate(Instrumentation.java:1105)
            at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2251)
            at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2360)
            at android.app.ActivityThread.handleRelaunchActivity(ActivityThread.java:3912)
            at android.app.ActivityThread.access$900(ActivityThread.java:144)
            at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1284)
            at android.os.Handler.dispatchMessage(Handler.java:102)
            at android.os.Looper.loop(Looper.java:135)
            at android.app.ActivityThread.main(ActivityThread.java:5221)
            at java.lang.reflect.Method.invoke(Native Method)
            at java.lang.reflect.Method.invoke(Method.java:372)
            at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:899)
            at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:694)

以下是MainActivity.java：

package com.example.asif.test;

import android.app.Activity;
import android.app.Fragment;
import android.app.FragmentManager;
import android.app.FragmentTransaction;
import android.support.v7.app.ActionBarActivity;
import android.os.Bundle;
import android.view.Menu;
import android.view.MenuItem;


public class MainActivity extends Activity {

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

        setContentView(R.layout.activity_main);

        FragmentManager fm = getFragmentManager();
        FragmentTransaction fragmentTransaction = fm.beginTransaction();
        Fragment fr = new FragmentOne();
        fragmentTransaction.replace(R.id.fragment_place, fr);
        fragmentTransaction.commit();
    }


    @Override
    public boolean onCreateOptionsMenu(Menu menu) {
        // Inflate the menu; this adds items to the action bar if it is present.
        getMenuInflater().inflate(R.menu.menu_main, menu);
        return true;
    }

    @Override
    public boolean onOptionsItemSelected(MenuItem item) {
        // Handle action bar item clicks here. The action bar will
        // automatically handle clicks on the Home/Up button, so long
        // as you specify a parent activity in AndroidManifest.xml.
        int id = item.getItemId();

        //noinspection SimplifiableIfStatement
        if (id == R.id.action_settings) {
            return true;
        }

        return super.onOptionsItemSelected(item);
    }
}

我的片段类FragmentOne.java：

package com.example.asif.test;

import android.content.Context;
import android.graphics.Canvas;
import android.graphics.Color;
import android.graphics.Paint;
import android.graphics.Rect;
import android.os.Bundle;
import android.app.Fragment;
import android.view.LayoutInflater;
import android.view.View;
import android.view.ViewGroup;
import android.widget.RelativeLayout;

public class FragmentOne extends Fragment 
{
    @Override
    public View onCreateView(LayoutInflater inflater, ViewGroup container,
                             Bundle savedInstanceState) {

        View rootView = inflater.inflate(R.layout.fragment_one, container, false);

        RelativeLayout relativeLayout = (RelativeLayout) rootView.findViewById(R.id.rect);
        relativeLayout.addView(new Rectangle(getActivity()));

        return rootView;
    }

    private class Rectangle extends View {
        Paint paint = new Paint();

        public Rectangle(Context context) {
            super(context);
        }
        @Override
        public void onDraw(Canvas canvas) {
            paint.setColor(Color.GREEN);
            Rect rect = new Rect(20, 56, 200, 112);
            canvas.drawRect(rect, paint );
        }
    }
}

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" android:paddingLeft="@dimen/activity_horizontal_margin"
    android:paddingRight="@dimen/activity_horizontal_margin"
    android:paddingTop="@dimen/activity_vertical_margin"
    android:paddingBottom="@dimen/activity_vertical_margin" tools:context=".MainActivity">
    <fragment android:name="com.example.asif.test.FragmentOne"
        android:id="@+id/fragment_place"
        android:layout_width="match_parent"
        android:layout_height="match_parent" />

</RelativeLayout>

这是FramgmentOne的布局文件fragment_one.xml：

<?xml version="1.0" encoding="utf-8"?>
<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:orientation="vertical"
    android:background="#fa6a6a"
    >


    <RelativeLayout
        android:layout_width="fill_parent"
        android:layout_height="fill_parent"
        android:layout_alignParentTop="true"
        android:layout_centerHorizontal="true"
        android:layout_marginTop="51dp"
        android:background="#444"
        android:id="@+id/rect">

    </RelativeLayout>
</RelativeLayout>

---

您的活动MainActivity必须扩展FragmentActivity。

---

另外，我认为最好使用android.support.v4.app.*classes Fragment、FragmentActivity等，这样你的应用程序就可以向后兼容。

我认为错误在于你的活动的xml。像这样更改活动布局的内容

<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" android:paddingLeft="@dimen/activity_horizontal_margin"
    android:paddingRight="@dimen/activity_horizontal_margin"
    android:paddingTop="@dimen/activity_vertical_margin"
    android:paddingBottom="@dimen/activity_vertical_margin" 
    android:id="@+id/fragment_place"
    tools:context=".MainActivity" />

---

谢谢你的回复。我照你说的做了，但还是得到了同样的例外。