title: Android: can't replace one fragment with another
body: <p>I need to replace a <code>Fragment</code> in one <code>Activity</code> with another <code>Fragment</code>, below is the layer file of the <code>Activity</code>:</p>
  
  <pre><code>&lt;?xml version="1.0" encoding="utf-8"?&gt;
  
  &lt;FrameLayout
    xmlns:android="http://schemas.android.com/apk/res/android"
    android:layout_width="fill_parent"
    android:layout_height="fill_parent"
    android:id="@+id/home_layout_container"&gt;
  
      &lt;fragment android:name="com.foo.FragA"
          android:id="@+id/home_list"
          android:layout_width="fill_parent"
          android:layout_height="fill_parent" /&gt;
  
      &lt;/FrameLayout&gt;
  </code></pre>
  
  <p>so by default there is <strong>FragA</strong>, now I want to replace it with <strong>FragB</strong> in activity, I did:</p>
  
  <pre><code>public void onRegionClicked(Region region) {
      RegionInfoFragment rif = RegionInfoFragment.newInstance(region);
      FragmentTransaction ft = getSupportFragmentManager().beginTransaction();
      ft.replace(R.id.home_list, rif);
  }
  </code></pre>
  
  <p>But I got exception:</p>
  
  <pre><code>&gt;6:24:40.685: ERROR/AndroidRuntime(9194): Uncaught handler: thread main exiting due to uncaught exception
  05-06 16:24:40.692: ERROR/AndroidRuntime(9194): java.lang.IllegalStateException: The specified child already has a parent. You must call removeView() on the child's parent first.
  05-06 16:24:40.692: ERROR/AndroidRuntime(9194):     at android.view.ViewGroup.addViewInner(ViewGroup.java:1857)
  05-06 16:24:40.692: ERROR/AndroidRuntime(9194):     at android.view.ViewGroup.addView(ViewGroup.java:1752)
  05-06 16:24:40.692: ERROR/AndroidRuntime(9194):     at android.view.ViewGroup.addView(ViewGroup.java:1709)
  05-06 16:24:40.692: ERROR/AndroidRuntime(9194):     at android.view.ViewGroup.addView(ViewGroup.java:1689)
  05-06 16:24:40.692: ERROR/AndroidRuntime(9194):     at android.support.v4.app.NoSaveStateFrameLayout.wrap(NoSaveStateFrameLayout.java:40)
  05-06 16:24:40.692: ERROR/AndroidRuntime(9194):     at android.support.v4.app.FragmentManagerImpl.moveToState(FragmentManager.java:743)
  05-06 16:24:40.692: ERROR/AndroidRuntime(9194):     at android.support.v4.app.FragmentManagerImpl.moveToState(FragmentManager.java:933)
  05-06 16:24:40.692: ERROR/AndroidRuntime(9194):     at android.support.v4.app.BackStackRecord.run(BackStackRecord.java:578)
  05-06 16:24:40.692: ERROR/AndroidRuntime(9194):     at android.support.v4.app.FragmentManagerImpl.execPendingActions(FragmentManager.java:1219)
  05-06 16:24:40.692: ERROR/AndroidRuntime(9194):     at android.support.v4.app.FragmentManagerImpl$1.run(FragmentManager.java:380)
  05-06 16:24:40.692: ERROR/AndroidRuntime(9194):     at android.os.Handler.handleCallback(Handler.java:587)
  05-06 16:24:40.692: ERROR/AndroidRuntime(9194):     at android.os.Handler.dispatchMessage(Handler.java:92)
  05-06 16:24:40.692: ERROR/AndroidRuntime(9194):     at android.os.Looper.loop(Looper.java:123)
  05-06 16:24:40.692: ERROR/AndroidRuntime(9194):     at android.app.ActivityThread.main(ActivityThread.java:4363)
  05-06 16:24:40.692: ERROR/AndroidRuntime(9194):     at java.lang.reflect.Method.invokeNative(Native Method)
  05-06 16:24:40.692: ERROR/AndroidRuntime(9194):     at java.lang.reflect.Method.invoke(Method.java:521)
  05-06 16:24:40.692: ERROR/AndroidRuntime(9194):     at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:860)
  05-06 16:24:40.692: ERROR/AndroidRuntime(9194):     at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:618)
  05-06 16:24:40.692: ERROR/AndroidRuntime(9194):     at dalvik.system.NativeStart.main(Native Method)
  </code></pre>
  
  <p>What can I do?</p>
  
  <p>Thanks!</p>