android context调用startActivity时报错：Calling startActivity() from outside of an Activity context ...

问题描述：

startActivity时报错Calling startActivity() from outside of an Activity context requires the FLAG_ACTIVITY_NEW_TASK flag

问题代码：

Intent intent = new Intent();
intent.setClass(mContext, PhotoView.class);
mContext.startActivity(intent);

问题分析：

Context中有一个startActivity方法，Activity继承自Context，重载了startActivity方法。

遇到上面那个异常的，是因为使用了Context的startActivity方法。

因为使用 Activity的startActivity方法，不会有任何限制

但是使用Context的startActivity方法的话，就需要开启一个新的task，

解决办法：

加一个flag：intent.addFlags(Intent.FLAG_ACTIVITY_NEW_TASK); 

正确代码：

Intent intent = new Intent();
intent.setClass(mContext, PhotoView.class);
intent.addFlags(Intent.FLAG_ACTIVITY_NEW_TASK);  
mContext.startActivity(intent);

报错日志：

06-28 11:24:40.359: E/AndroidRuntime(7397): android.util.AndroidRuntimeException: Calling startActivity() from outside of an Activity  context requires the FLAG_ACTIVITY_NEW_TASK flag. Is this really what you want?
06-28 11:24:40.359: E/AndroidRuntime(7397):     at android.app.ContextImpl.startActivity(ContextImpl.java:617)
06-28 11:24:40.359: E/AndroidRuntime(7397):     at android.content.ContextWrapper.startActivity(ContextWrapper.java:258)
06-28 11:24:40.359: E/AndroidRuntime(7397):     at com.hotalk.ui.homepage.favorites.FavoritesListAdapter$7.onClick(FavoritesListAdapter.java:1509)
06-28 11:24:40.359: E/AndroidRuntime(7397):     at android.view.View.performClick(View.java:2408)
06-28 11:24:40.359: E/AndroidRuntime(7397):     at android.view.View$PerformClick.run(View.java:8816)
06-28 11:24:40.359: E/AndroidRuntime(7397):     at android.os.Handler.handleCallback(Handler.java:587)
06-28 11:24:40.359: E/AndroidRuntime(7397):     at android.os.Handler.dispatchMessage(Handler.java:92)
06-28 11:24:40.359: E/AndroidRuntime(7397):     at android.os.Looper.loop(Looper.java:123)
06-28 11:24:40.359: E/AndroidRuntime(7397):     at android.app.ActivityThread.main(ActivityThread.java:4627)
06-28 11:24:40.359: E/AndroidRuntime(7397):     at java.lang.reflect.Method.invokeNative(Native Method)
06-28 11:24:40.359: E/AndroidRuntime(7397):     at java.lang.reflect.Method.invoke(Method.java:521)
06-28 11:24:40.359: E/AndroidRuntime(7397):     at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:868)
06-28 11:24:40.359: E/AndroidRuntime(7397):     at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:626)
06-28 11:24:40.359: E/AndroidRuntime(7397):     at dalvik.system.NativeStart.main(Native Method)

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参考链接：

https://www.cnblogs.com/Free-Thinker/p/6707506.html