安卓系统:DatePicker文本视图DMY格式，并希望将其保存为YMD格式

Question

我有一个可点击的文本视图，并有一个日期选择器对话框。日期选择器然后将文本视图中的日期设置为DAY、MONTH、YEAR格式。我想以年、月、日的格式存储它。我希望它在文本视图中显示为DMY，但在SQLITE中，它必须存储为YDM。我做了下面的方法，但它给了我非法的例外。

private void updateDisplay() {
    date.setText(new StringBuilder()
            .append(mDay).append("-")
            .append(mMonth + 1).append("-")
            .append(mYear));   
String datepicker = date_tv.getText().toString();
SimpleDateFormat sdf= new SimpleDateFormat("yyyy-MM-dd", java.util.Locale.getDefault());
datepicker = sdf.format(date_tv);
cv = new ContentValues();
cv.put(DBAdapter.COLUMN_METER_DATE, datepicker);

它给了我以下错误

02-26 08:42:07.114: E/AndroidRuntime(5109): FATAL EXCEPTION: main
02-26 08:42:07.114: E/AndroidRuntime(5109): Process: com.example.mscprojectimagebuttons, PID: 5109
02-26 08:42:07.114: E/AndroidRuntime(5109): java.lang.IllegalArgumentException: Bad class: class android.widget.TextView
02-26 08:42:07.114: E/AndroidRuntime(5109):     at java.text.DateFormat.format(DateFormat.java:296)
02-26 08:42:07.114: E/AndroidRuntime(5109):     at java.text.Format.format(Format.java:93)
02-26 08:42:07.114: E/AndroidRuntime(5109):     at com.example.mscprojectimagebuttons.MeterFragment$2.onClick(MeterFragment.java:98)
02-26 08:42:07.114: E/AndroidRuntime(5109):     at android.view.View.performClick(View.java:4438)
02-26 08:42:07.114: E/AndroidRuntime(5109):     at android.view.View$PerformClick.run(View.java:18422)
02-26 08:42:07.114: E/AndroidRuntime(5109):     at android.os.Handler.handleCallback(Handler.java:733)
 02-26 08:42:07.114: E/AndroidRuntime(5109):    at android.os.Handler.dispatchMessage(Handler.java:95)
02-26 08:42:07.114: E/AndroidRuntime(5109):     at android.os.Looper.loop(Looper.java:136)
 02-26 08:42:07.114: E/AndroidRuntime(5109):    at android.app.ActivityThread.main(ActivityThread.java:5017)
02-26 08:42:07.114: E/AndroidRuntime(5109):     at java.lang.reflect.Method.invokeNative(Native Method)
 02-26 08:42:07.114: E/AndroidRuntime(5109):    at java.lang.reflect.Method.invoke(Method.java:515)
 02-26 08:42:07.114: E/AndroidRuntime(5109):    at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:779)
 02-26 08:42:07.114: E/AndroidRuntime(5109):    at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:595)
 02-26 08:42:07.114: E/AndroidRuntime(5109):    at dalvik.system.NativeStart.main(Native Method)

Answer 1

更换

datepicker = sdf.format(date_tv);

通过

datepicker = sdf.format(datepicker);