Android 将对象保存到bandle时出错
当我的手机旋转时,我想保存我的课程。我的代码是:Android 将对象保存到bandle时出错,android,eclipse,Android,Eclipse,当我的手机旋转时,我想保存我的课程。我的代码是: public class MainActivity extends FragmentActivity { private MapCanvas mapCanvas = null; @Override public void onCreate(Bundle savedInstanceState) { super.onCreate(savedInstanceState)
public class MainActivity extends FragmentActivity
{
private MapCanvas mapCanvas = null;
@Override
public void onCreate(Bundle savedInstanceState)
{
super.onCreate(savedInstanceState);
if(savedInstanceState == null)
{
this.mapCanvas = new MapCanvas(this);
}
else
{
this.mapCanvas = (MapCanvas)savedInstanceState.getSerializable("s");
}
setContentView(this.mapCanvas);
this.mapCanvas.requestFocus();
}
@Override
protected void onSaveInstanceState(Bundle outState)
{
super.onSaveInstanceState(outState);
outState.putSerializable("s", this.mapCanvas);
}
}
但当我旋转手机时,我在第setContentView(this.mapCanvas)行中遇到了错误代码>
我的地图画布是:
public class MapCanvas extends ImageView implements Serializable
{
private static final long serialVersionUID = 1L;
....
}
我的日志聊天是:
11-27 20:09:37.969: W/dalvikvm(14743): threadid=1: thread exiting with uncaught exception (group=0x40187560)
11-27 20:09:37.999: E/AndroidRuntime(14743): FATAL EXCEPTION: main
11-27 20:09:37.999: E/AndroidRuntime(14743): java.lang.RuntimeException: Unable to start activity ComponentInfo{ir.pangan.yazdbakishni/ir.pangan.yazdbakishni.activities.MainActivity}: java.lang.IllegalStateException: The specified child already has a parent. You must call removeView() on the child's parent first.
11-27 20:09:37.999: E/AndroidRuntime(14743): at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:1659)
11-27 20:09:37.999: E/AndroidRuntime(14743): at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:1675)
11-27 20:09:37.999: E/AndroidRuntime(14743): at android.app.ActivityThread.handleRelaunchActivity(ActivityThread.java:2844)
11-27 20:09:37.999: E/AndroidRuntime(14743): at android.app.ActivityThread.access$1600(ActivityThread.java:121)
11-27 20:09:37.999: E/AndroidRuntime(14743): at android.app.ActivityThread$H.handleMessage(ActivityThread.java:947)
11-27 20:09:37.999: E/AndroidRuntime(14743): at android.os.Handler.dispatchMessage(Handler.java:99)
11-27 20:09:37.999: E/AndroidRuntime(14743): at android.os.Looper.loop(Looper.java:130)
11-27 20:09:37.999: E/AndroidRuntime(14743): at android.app.ActivityThread.main(ActivityThread.java:3768)
11-27 20:09:37.999: E/AndroidRuntime(14743): at java.lang.reflect.Method.invokeNative(Native Method)
11-27 20:09:37.999: E/AndroidRuntime(14743): at java.lang.reflect.Method.invoke(Method.java:507)
11-27 20:09:37.999: E/AndroidRuntime(14743): at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:878)
11-27 20:09:37.999: E/AndroidRuntime(14743): at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:636)
11-27 20:09:37.999: E/AndroidRuntime(14743): at dalvik.system.NativeStart.main(Native Method)
11-27 20:09:37.999: E/AndroidRuntime(14743): Caused by: java.lang.IllegalStateException: The specified child already has a parent. You must call removeView() on the child's parent first.
11-27 20:09:37.999: E/AndroidRuntime(14743): at android.view.ViewGroup.addViewInner(ViewGroup.java:1976)
11-27 20:09:37.999: E/AndroidRuntime(14743): at android.view.ViewGroup.addView(ViewGroup.java:1871)
11-27 20:09:37.999: E/AndroidRuntime(14743): at android.view.ViewGroup.addView(ViewGroup.java:1851)
11-27 20:09:37.999: E/AndroidRuntime(14743): at com.android.internal.policy.impl.PhoneWindow.setContentView(PhoneWindow.java:226)
11-27 20:09:37.999: E/AndroidRuntime(14743): at com.android.internal.policy.impl.PhoneWindow.setContentView(PhoneWindow.java:216)
11-27 20:09:37.999: E/AndroidRuntime(14743): at android.app.Activity.setContentView(Activity.java:1668)
11-27 20:09:37.999: E/AndroidRuntime(14743): at ir.pangan.yazdbakishni.activities.MainActivity.onCreate(MainActivity.java:37)
11-27 20:09:37.999: E/AndroidRuntime(14743): at android.app.Instrumentation.callActivityOnCreate(Instrumentation.java:1047)
11-27 20:09:37.999: E/AndroidRuntime(14743): at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:1623)
11-27 20:09:37.999: E/AndroidRuntime(14743): ... 12 more
不能将控件存储在捆绑包中。您必须在每次onCreate调用时重新创建所有视图,但可以保存该自定义视图的内部状态。这也可以通过自定义构造函数恢复
请参见我的示例:
public class MapCanvas extends ImageView {
public MapCanvas(Context c, Bundle state) {
super(c);
recoverState(state);
}
public recoverState(Bundle state) {
if(state==null) {
return;
}
// read values...
}
public Bundle saveState(Bundle outState) {
// save whatever you want.
}
}
这是您修改的活动:
public class MainActivity extends FragmentActivity {
private MapCanvas mapCanvas = null;
@Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
mapCanvas = new MapCanvas(this, savedInstanceState);
setContentView(mapCanvas);
mapCanvas.requestFocus();
}
@Override
protected void onSaveInstanceState(Bundle outState) {
super.onSaveInstanceState(outState);
mapCanvas.saveState(outState);
}
}
我可以从logcat中知道错误吗…@shylendra是的,请查看我上面的编辑