新的Android和Java真的(我最初是一名Pascal程序员)并且遇到了问题 - 我的应用程序正在关闭,我无法解决原因。Android部队关闭错误
我只是试图调用一个活动来显示我的(当前为空)数据库中的数据表。我正在使用'学习Android'书籍,并且大部分代码都被剪掉并粘贴了。我已将所有数据库访问例程重构为特定的类,但似乎是一个问题。
调用方法:
@Override
public void onResume() {
super.onResume();
Log.i(TAG, "In onResume...");
// Link to WYWHApplication module
WYWHApplication wywh = (WYWHApplication) this.getApplication();
// Fetch trip list
Cursor tripList = wywh.getBasicList();
,这是DB类:
public class WYWHApplication extends Application {
private static final String TAG = WYWHApplication.class.getSimpleName();
@Override
public void onCreate() {
super.onCreate();
Log.i(TAG, "In onCreate for app...");
}
@Override
public void onTerminate() {
super.onTerminate();
Log.i(TAG, "In onTerminate for app...");
}
// Link to DB class
private DatabaseUtils dbUtils;
// Accessor method - how other modules get access to DB.
public DatabaseUtils getDBData() {
return dbUtils;
}
public synchronized Cursor getBasicList() {
Log.i(TAG, "Getting basic list of trips");
// Get list of DB entries
Cursor tripEntries = this.getDBData().fetchList("TRIP_TABLE");
Log.i(TAG, "...returned from getting basic list of trips");
return tripEntries;
}
的logcat的有以下几点:
10-14 20:38:29.543: INFO/WYWHApplication(305): In onCreate for app...
10-14 20:38:29.603: DEBUG/WYWH(305): Start of onCreate....
10-14 20:38:30.283: DEBUG/WYWH(305): ...end of onCreate.
10-14 20:41:05.943: INFO/ActivityManager(58): Starting activity: Intent { cmp=co.uk.sanetech.wywh/.TripsScreenActivity }
10-14 20:41:06.183: INFO/Trips(305): Start of onCreate....
10-14 20:41:06.773: INFO/Trips(305): In onResume...
10-14 20:41:06.773: INFO/WYWHApplication(305): Getting basic list of trips
10-14 20:41:06.793: DEBUG/AndroidRuntime(305): Shutting down VM
10-14 20:41:06.793: WARN/dalvikvm(305): threadid=1: thread exiting with uncaught exception (group=0x4001d800)
10-14 20:41:06.993: ERROR/AndroidRuntime(305): FATAL EXCEPTION: main
10-14 20:41:06.993: ERROR/AndroidRuntime(305): java.lang.RuntimeException: Unable to resume activity {co.uk.sanetech.wywh/co.uk.sanetech.wywh.TripsScreenActivity}: java.lang.NullPointerException
10-14 20:41:06.993: ERROR/AndroidRuntime(305): at android.app.ActivityThread.performResumeActivity(ActivityThread.java:3128)
(左位在这里)
10-14 20:41:06.993: ERROR/AndroidRuntime(305): Caused by: java.lang.NullPointerException
10-14 20:41:06.993: ERROR/AndroidRuntime(305): at co.uk.sanetech.wywh.WYWHApplication.getBasicList(WYWHApplication.java:36)
10-14 20:41:06.993: ERROR/AndroidRuntime(305): at co.uk.sanetech.wywh.TripsScreenActivity.onResume(TripsScreenActivity.java:42)
10-14 20:41:06.993: ERROR/AndroidRuntime(305): at android.app.Instrumentation.callActivityOnResume(Instrumentation.java:1149)
10-14 20:41:06.993: ERROR/AndroidRuntime(305): at android.app.Activity.performResume(Activity.java:3823)
10-14 20:41:06.993: ERROR/AndroidRuntime(305): at android.app.ActivityThread.performResumeActivity(ActivityThread.java:3118)
10-14 20:41:06.993: ERROR/AndroidRuntime(305): ... 12 more
代码fetchList:
public Cursor fetchList(String tabName) {
Log.i(TAG, "In fetchList...");
...因为我没有得到这最后的调试消息,这表明,(我)这个问题是调用fetchList但不知道为什么。
感激地接受任何帮助......
非常好 - 这就是诀窍 - 非常感谢(接下来的错误!)... – Nelmo
您的欢迎。如果我的回答对您有帮助,请随时接受它,谢谢。 – Devunwired