[英]Intent crashing when trying to navigate to Previous activity
Basically, I don't know why, but when I try to go from one activity to the previous one ( using ym back button) the intent is null, therefore null pointer exception. 基本上,我不知道为什么,但是当我尝试从一个活动转到上一个活动(使用ym后退按钮)时,intent为null,因此为null指针异常。
The way I do the intent is: 我这样做的目的是:
Intent intent = new Intent(Puzzle_Activity.this, Play_Activity.class );
startActivity(intent);
and there's nothing wrong with that code as far as I know. 据我所知,该代码没有任何问题。 yet the logcat is giving me
但是logcat给了我
04-24 19:23:15.074: E/AndroidRuntime(829): FATAL EXCEPTION: main
04-24 19:23:15.074: E/AndroidRuntime(829): java.lang.RuntimeException: Unable to start activity ComponentInfo{com.example.angrywordsearch/com.example.angrywordsearch.Play_Activity}: java.lang.NullPointerException
04-24 19:23:15.074: E/AndroidRuntime(829): at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2059)
04-24 19:23:15.074: E/AndroidRuntime(829): at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2084)
04-24 19:23:15.074: E/AndroidRuntime(829): at android.app.ActivityThread.access$600(ActivityThread.java:130)
04-24 19:23:15.074: E/AndroidRuntime(829): at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1195)
04-24 19:23:15.074: E/AndroidRuntime(829): at android.os.Handler.dispatchMessage(Handler.java:99)
04-24 19:23:15.074: E/AndroidRuntime(829): at android.os.Looper.loop(Looper.java:137)
04-24 19:23:15.074: E/AndroidRuntime(829): at android.app.ActivityThread.main(ActivityThread.java:4745)
04-24 19:23:15.074: E/AndroidRuntime(829): at java.lang.reflect.Method.invokeNative(Native Method)
04-24 19:23:15.074: E/AndroidRuntime(829): at java.lang.reflect.Method.invoke(Method.java:511)
04-24 19:23:15.074: E/AndroidRuntime(829): at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:786)
04-24 19:23:15.074: E/AndroidRuntime(829): at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:553)
04-24 19:23:15.074: E/AndroidRuntime(829): at dalvik.system.NativeStart.main(Native Method)
04-24 19:23:15.074: E/AndroidRuntime(829): Caused by: java.lang.NullPointerException
04-24 19:23:15.074: E/AndroidRuntime(829): at com.example.angrywordsearch.Play_Activity.onCreate(Play_Activity.java:60)
04-24 19:23:15.074: E/AndroidRuntime(829): at android.app.Activity.performCreate(Activity.java:5008)
04-24 19:23:15.074: E/AndroidRuntime(829): at android.app.Instrumentation.callActivityOnCreate(Instrumentation.java:1079)
04-24 19:23:15.074: E/AndroidRuntime(829): at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2023)
04-24 19:23:15.074: E/AndroidRuntime(829): ... 11 more
So what I'm asking is; 所以我要问的是 Why is it null if I specify the classes to go to?
如果指定要转到的类,为什么它为null?
Play activity 玩活动
@Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
Intent Newintent = getParent().getIntent(); // Line 60
Bundle extras = Newintent.getExtras();
if(Newintent.hasExtra("userName"))
{
userName = extras.getString("userName");
Password = extras.getString("Password");
}
setContentView(R.layout.play_layout);
}
You should be using getIntent()
instead of getParent().getIntent()
, getParent()
is probably null. 您应该使用
getIntent()
而不是getParent().getIntent()
, getParent()
可能为null。
getIntent()
gives you the intent that the activity was started with. getIntent()
提供了活动开始的意图。
Documentation says: 文档说:
public final Activity getParent ()
Since: API Level 1 public final Activity getParent ()
从:API级别1
Return the parent activity if this view is an embedded child. 如果此视图是嵌入式子级,则返回父级活动。
Is your Activity an embedded child? 您的活动是嵌入式孩子吗?
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