我有以下情况,这是相当拉我的头发:我正在写一个类来管理Android相机,它扩展了活动。在那个类里面我有下面的代码。什么情况是,我总是得到零点异常--with其强制关闭小friend--在这行:Android:startActivityForResult始终为空并强制关闭我的应用程序
startActivityForResult(intent, 0);
但是我得到的System.out.println(“故意不为空”);印在logcat中确定...
的logcat的说:
03-08 22:46:38.584: ERROR/AndroidRuntime(1079): java.lang.NullPointerException
03-08 22:46:38.584: ERROR/AndroidRuntime(1079): at android.app.Activity.startActivityForResult(Activity.java:2749)
03-08 22:46:38.584: ERROR/AndroidRuntime(1079): at com.test.cameratest.startCameraActivity(cameratest.java:39)
在清单中,我有:
<uses-permission android:name="android.permission.WRITE_EXTERNAL_STORAGE" />
<uses-permission android:name="android.permission.CAMERA" />
<uses-feature android:name="android.hardware.camera"/>
<activity android:name=".cameratest" />
所以,我在做什么错?为什么startActivityForResult总是抛出null!?
@Override
public void onCreate(Bundle savedInstanceState)
{
super.onCreate(savedInstanceState);
}
/** As per suggestion tried to change the method from protected to private or public
but still have the same problem */
protected void startCameraActivity()
{
String path = (new StringBuilder()).append(Environment.getExternalStorageDirectory()).append("/images/test.jpg").toString();
System.out.println("started");
File file = new File(path);
System.out.println(path);
Uri outputFileUri = Uri.fromFile(file);
Intent intent = new Intent("android.media.action.IMAGE_CAPTURE");
intent.putExtra("output", outputFileUri);
/** Removed as per suggestion
if (intent!=null)
{
System.out.println("intent not null");
**startActivityForResult(intent, 0);**
}
*/
**startActivityForResult(intent, 0);** <== null pointer exception
}
编辑:
按照建议,我接过来一看从Android 2.1r2框架上Activity.java线2749和这里是代码:
public void startActivityForResult(Intent intent, int requestCode) {
if (mParent == null) {
**** Line 2749 is the folowing
Instrumentation.ActivityResult ar =
mInstrumentation.execStartActivity(
this, mMainThread.getApplicationThread(), mToken, this,
intent, requestCode);
****
if (ar != null) {
mMainThread.sendActivityResult(
mToken, mEmbeddedID, requestCode, ar.getResultCode(),
ar.getResultData());
}
if (requestCode >= 0) {
// If this start is requesting a result, we can avoid making
// the activity visible until the result is received. Setting
// this code during onCreate(Bundle savedInstanceState) or onResume() will keep the
// activity hidden during this time, to avoid flickering.
// This can only be done when a result is requested because
// that guarantees we will get information back when the
// activity is finished, no matter what happens to it.
mStartedActivity = true;
}
} else {
mParent.startActivityFromChild(this, intent, requestCode);
}
}
线2749标有双**但是,我没有看到该代码的问题
EDITED
忘了解释我是如何把这种:
cameratest cam = new cameratest();
cam.startCameraActivity();
既然你已经过了'intent.putExtra(...)',那么检查'intent!= null'是没用的。这不是问题。我会看看你正在使用的操作系统版本的Activity.java 2749行。这可能会提供一个提示。你可以在这里找到框架源码(http://android.git.kernel.org/?p=platform/frameworks/base.git;a=summary) –
谢谢泰德,但是我没有看到问题没有,或者据我所知。我还发现,无论我想开始什么活动,它总是会抛出一个空的异常错误。我试着用snippets来获取联系人并拨打一个号码... –
我认为问题可能是由于受保护的方法所致。请尝试使用私人的方式 –