我想做一个d天的小部件。在MainActivity中，我使用了像这样的SharedPreferences
public class MainActivity extends Activity {
int startDay;
int startMonth;
int startYear;
int id = 1128;
long days;
long diff;
int countNumber;
boolean notifyClicked;
EditText txtview;
TextView dayCount;
String message;
DatePicker datePicker;
PendingIntent resultPendingIntent;
Context context;
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
context = this;
txtview = (EditText) findViewById(R.id.txtfield);
dayCount = (TextView) findViewById(R.id.days);
datePicker = (DatePicker) findViewById(R.id.datePicker);
Button startBtn = (Button) findViewById(R.id.btn1);
// SharedPreferences Load
SharedPreferences pref = getSharedPreferences("SaveState", 0);
startDay = pref.getInt("startDay", 0);
startMonth = pref.getInt("startMonth", 0);
startYear = pref.getInt("startYear", 0);
message = pref.getString("message", "");
countNumber = pref.getInt("countNumber", 0);
txtview.setText(message);
startBtn.setOnClickListener(new OnClickListener() {
@Override
public void onClick(View v) {
// TODO Auto-generated method stub
startDay = datePicker.getDayOfMonth();
startMonth = datePicker.getMonth() + 1;
startYear = datePicker.getYear();
message = txtview.getText().toString();
// SharedPreferences Save
SharedPreferences pref = getSharedPreferences("SaveState", 0);
SharedPreferences.Editor edit = pref.edit();
edit.putInt("startDay", startDay);
edit.putInt("startMonth", startMonth);
edit.putInt("startYear", startYear);
edit.putString("message", message);
edit.putInt("countNumber", countNumber);
edit.commit();
Calendar thatDay = Calendar.getInstance();
thatDay.set(Calendar.DAY_OF_MONTH, startDay);
thatDay.set(Calendar.MONTH, startMonth - 1); // 0-11 so 1 less
thatDay.set(Calendar.YEAR, startYear);
Calendar today = Calendar.getInstance();
diff = today.getTimeInMillis() - thatDay.getTimeInMillis();
days = diff / (24 * 60 * 60 * 1000);
countNumber = (int) days;
Toast.makeText(getApplicationContext(),
countNumber + "일 지났습니다. 알림 버튼을 눌러주세요.",
Toast.LENGTH_SHORT).show();
}
});
Intent resultIntent = new Intent(this, ExampleActivity.class);
resultPendingIntent = PendingIntent.getActivity(this, 0, resultIntent,
0);
Button setBtn = (Button) findViewById(R.id.btn2);
setBtn.setOnClickListener(new OnClickListener() {
@Override
public void onClick(View v) {
// TODO Auto-generated method stub
long firstTime = SystemClock.elapsedRealtime();
firstTime += 10 * 1000;
AlarmManager am = (AlarmManager) getSystemService(ALARM_SERVICE);
am.setRepeating(AlarmManager.ELAPSED_REALTIME_WAKEUP,
firstTime, 10 * 1000, resultPendingIntent);
}
});
}
并做了一个新的IntentActivity扩展BroadcastReceiver，它发出通知
public class ExampleActivity extends BroadcastReceiver {
int startDay;
int startMonth;
int startYear;
int id = 1128;
String message;
int countNumber;
NotificationCompat.Builder mBuilder;
NotificationManager mNotificationManager;
@Override
public void onReceive(Context arg0, Intent arg1) {
// TODO Auto-generated method stub
PendingIntent contentIntent = PendingIntent.getActivity(arg0, 0,
new Intent(arg0, MainActivity.class), 0);
SharedPreferences pref = arg0.getSharedPreferences("SaveState",
Context.MODE_PRIVATE);
startDay = pref.getInt("startDay", 0);
startMonth = pref.getInt("startMonth", 0);
startYear = pref.getInt("startYear", 0);
countNumber = pref.getInt("countNumber", 0);
message = pref.getString("message", "");
mBuilder = new NotificationCompat.Builder(arg0)
.setSmallIcon(R.drawable.heart)
.setContentText(countNumber + "")
.setContentTitle(message + "")
.setContentIntent(contentIntent);
mBuilder.setOngoing(true);
mNotificationManager = (NotificationManager) arg0
.getSystemService(Context.NOTIFICATION_SERVICE);
mNotificationManager.notify(id, mBuilder.build());
}
}
但是当我想要这个ExampleActivity时它会强制关闭。编译时没有错误。 这是一个错误日志。
02-20 22:47:21.137: E/AndroidRuntime(4985): FATAL EXCEPTION: main
02-20 22:47:21.137: E/AndroidRuntime(4985): Process: com.example.calculateday, PID: 4985
02-20 22:47:21.137: E/AndroidRuntime(4985): java.lang.RuntimeException: Unable to instantiate activity ComponentInfo{com.example.calculateday/com.example.calculateday.ExampleActivity}: java.lang.ClassCastException: com.example.calculateday.ExampleActivity cannot be cast to android.app.Activity
02-20 22:47:21.137: E/AndroidRuntime(4985): at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2124)
02-20 22:47:21.137: E/AndroidRuntime(4985): at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2248)
02-20 22:47:21.137: E/AndroidRuntime(4985): at android.app.ActivityThread.access$800(ActivityThread.java:138)
02-20 22:47:21.137: E/AndroidRuntime(4985): at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1199)
02-20 22:47:21.137: E/AndroidRuntime(4985): at android.os.Handler.dispatchMessage(Handler.java:102)
02-20 22:47:21.137: E/AndroidRuntime(4985): at android.os.Looper.loop(Looper.java:136)
02-20 22:47:21.137: E/AndroidRuntime(4985): at android.app.ActivityThread.main(ActivityThread.java:5050)
02-20 22:47:21.137: E/AndroidRuntime(4985): at java.lang.reflect.Method.invokeNative(Native Method)
02-20 22:47:21.137: E/AndroidRuntime(4985): at java.lang.reflect.Method.invoke(Method.java:515)
02-20 22:47:21.137: E/AndroidRuntime(4985): at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:779)
02-20 22:47:21.137: E/AndroidRuntime(4985): at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:595)
02-20 22:47:21.137: E/AndroidRuntime(4985): at dalvik.system.NativeStart.main(Native Method)
02-20 22:47:21.137: E/AndroidRuntime(4985): Caused by: java.lang.ClassCastException: com.example.calculateday.ExampleActivity cannot be cast to android.app.Activity
02-20 22:47:21.137: E/AndroidRuntime(4985): at android.app.Instrumentation.newActivity(Instrumentation.java:1061)
02-20 22:47:21.137: E/AndroidRuntime(4985): at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2115)
02-20 22:47:21.137: E/AndroidRuntime(4985): ... 11 more
答案 0 :(得分：0)
使用PendingIntent.getBroadcast代替PendingIntent.getAcivity获取ExampleActivity的待定内容：
resultPendingIntent = PendingIntent.getBroadcast(this, 0, resultIntent,
0);
因为ExampleActivity是BroadcastReceiver而不是Activity。