基本上,我不知道爲什麼,但是當我嘗試從一個活動轉到上一個時(使用ym後退按鈕) 意圖爲空,因此空指針異常。試圖導航到以前的活動時意圖崩潰
我做的意圖的方法是:
Intent intent = new Intent(Puzzle_Activity.this, Play_Activity.class);
startActivity(intent);
並沒有什麼錯代碼據我所知。 然而,logcat的是給我
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
那麼,我問的是;爲什麼如果我指定要去的類,它爲空?
Play活動
@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);
}
在'Play_Activity'中顯示'onCreate()' – 2013-04-24 19:26:39
特別是第60行 – 323go 2013-04-24 19:27:07
第60行:Intent Newintent = getParent()。getIntent(); – 2013-04-24 19:28:58