多个DatePickers，在屏幕旋转时强制关闭

这是我的第一个Android应用程序，在此之前我根本没有Java知识。 我使用了下面的代码（在Adam L.的另一个问题中找到），我有28个时间戳，在改变代码之后效果很好。 但有一点我注意到，当我在timepickerdialog（或使用此处显示的代码时的datepickerdialog）并更改屏幕方向时，我会强制关闭（nullpointerexception）。 我想我需要使用onDestroy保存一些信息并使用onStart再次恢复它，但我不知道如何实现这一点。 在我自己的代码中，我使用timepickerdialogs，但Adam L.s代码更清晰，所以解决问题也可以解决我自己的问题。 
import java.util.Calendar;
import android.app.Activity;
import android.app.DatePickerDialog;
import android.app.Dialog;
import android.app.DatePickerDialog.OnDateSetListener;
import android.os.Bundle;
import android.view.View;
import android.widget.Button;
import android.widget.DatePicker;
import android.widget.TextView;

public class MultiDatePickerActivity extends Activity {

private TextView startDateDisplay;
private TextView endDateDisplay;
private Button startPickDate;
private Button endPickDate;
private Calendar startDate;
private Calendar endDate;

static final int DATE_DIALOG_ID = 0;

private TextView activeDateDisplay;
private Calendar activeDate;

protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.multidatepicker);

    /*  capture our View elements for the start date function   */
    startDateDisplay = (TextView) findViewById(R.id.startDateDisplay);
    startPickDate = (Button) findViewById(R.id.startPickDate);

    /* get the current date */
    startDate = Calendar.getInstance();

    /* add a click listener to the button   */
    startPickDate.setOnClickListener(new View.OnClickListener() {
        public void onClick(View v) {
            showDateDialog(startDateDisplay, startDate);
        }
    });

    /* capture our View elements for the end date function */
    endDateDisplay = (TextView) findViewById(R.id.endDateDisplay);
    endPickDate = (Button) findViewById(R.id.endPickDate);

    /* get the current date */
    endDate = Calendar.getInstance();

    /* add a click listener to the button   */
    endPickDate.setOnClickListener(new View.OnClickListener() {
        public void onClick(View v) {
            showDateDialog(endDateDisplay, endDate);
        }
    });

    /* display the current date (this method is below)  */
    updateDisplay(startDateDisplay, startDate);
    updateDisplay(endDateDisplay, endDate);
}

private void updateDisplay(TextView dateDisplay, Calendar date) {
    dateDisplay.setText(
            new StringBuilder()
                // Month is 0 based so add 1
                .append(date.get(Calendar.MONTH) + 1).append("-")
                .append(date.get(Calendar.DAY_OF_MONTH)).append("-")
                .append(date.get(Calendar.YEAR)).append(" "));

}

public void showDateDialog(TextView dateDisplay, Calendar date) {
    activeDateDisplay = dateDisplay;
    activeDate = date;
    showDialog(DATE_DIALOG_ID);
}

private OnDateSetListener dateSetListener = new OnDateSetListener() {
    @Override
    public void onDateSet(DatePicker view, int year, int monthOfYear, int dayOfMonth) {
        activeDate.set(Calendar.YEAR, year);
        activeDate.set(Calendar.MONTH, monthOfYear);
        activeDate.set(Calendar.DAY_OF_MONTH, dayOfMonth);
        updateDisplay(activeDateDisplay, activeDate);
        unregisterDateDisplay();
    }
};

private void unregisterDateDisplay() {
    activeDateDisplay = null;
    activeDate = null;
}

@Override
protected Dialog onCreateDialog(int id) {
    switch (id) {
        case DATE_DIALOG_ID:
            return new DatePickerDialog(this, dateSetListener, activeDate.get(Calendar.YEAR), activeDate.get(Calendar.MONTH), activeDate.get(Calendar.DAY_OF_MONTH));
    }
    return null;
}

@Override
protected void onPrepareDialog(int id, Dialog dialog) {
    super.onPrepareDialog(id, dialog);
    switch (id) {
        case DATE_DIALOG_ID:
            ((DatePickerDialog) dialog).updateDate(activeDate.get(Calendar.YEAR), activeDate.get(Calendar.MONTH), activeDate.get(Calendar.DAY_OF_MONTH));
            break;
    }
}
}
我认为这是Eclipse中logcat的有趣部分： 
12-18 11:32:52.415: INFO/ActivityManager(577): Displayed activity se.bergsland.manydatepickers/.ManyDatePickers: 993 ms
12-18 11:32:57.625: DEBUG/dalvikvm(1734): GC freed 1950 objects / 104136 bytes in 192ms
12-18 11:33:00.396: INFO/WindowManager(577): Config changed: { scale=1.0 imsi=0/0 locale=en_US touch=3 key=2/1/2 nav=3 orien=2 }
12-18 11:33:00.535: DEBUG/StatusBar(577): updateResources
12-18 11:33:00.595: DEBUG/AndroidRuntime(1763): Shutting down VM
12-18 11:33:00.595: WARN/dalvikvm(1763): threadid=3: thread exiting with uncaught exception (group=0x4000fe70)
12-18 11:33:00.605: ERROR/AndroidRuntime(1763): Uncaught handler: thread main exiting due to uncaught exception
12-18 11:33:00.615: INFO/WindowManager(577): onOrientationChanged, rotation changed to 0
12-18 11:33:00.625: ERROR/AndroidRuntime(1763): java.lang.RuntimeException: Unable to start activity ComponentInfo{se.bergsland.manydatepickers/se.bergsland.manydatepickers.ManyDatePickers}: java.lang.NullPointerException
12-18 11:33:00.625: ERROR/AndroidRuntime(1763):     at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2268)
12-18 11:33:00.625: ERROR/AndroidRuntime(1763):     at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2284)
12-18 11:33:00.625: ERROR/AndroidRuntime(1763):     at android.app.ActivityThread.handleRelaunchActivity(ActivityThread.java:3278)
12-18 11:33:00.625: ERROR/AndroidRuntime(1763):     at android.app.ActivityThread.access$1900(ActivityThread.java:112)
12-18 11:33:00.625: ERROR/AndroidRuntime(1763):     at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1696)
12-18 11:33:00.625: ERROR/AndroidRuntime(1763):     at android.os.Handler.dispatchMessage(Handler.java:99)
12-18 11:33:00.625: ERROR/AndroidRuntime(1763):     at android.os.Looper.loop(Looper.java:123)
12-18 11:33:00.625: ERROR/AndroidRuntime(1763):     at android.app.ActivityThread.main(ActivityThread.java:3948)
12-18 11:33:00.625: ERROR/AndroidRuntime(1763):     at java.lang.reflect.Method.invokeNative(Native Method)
12-18 11:33:00.625: ERROR/AndroidRuntime(1763):     at java.lang.reflect.Method.invoke(Method.java:521)
12-18 11:33:00.625: ERROR/AndroidRuntime(1763):     at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:782)
12-18 11:33:00.625: ERROR/AndroidRuntime(1763):     at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:540)
12-18 11:33:00.625: ERROR/AndroidRuntime(1763):     at dalvik.system.NativeStart.main(Native Method)
12-18 11:33:00.625: ERROR/AndroidRuntime(1763): Caused by: java.lang.NullPointerException
12-18 11:33:00.625: ERROR/AndroidRuntime(1763):     at se.bergsland.manydatepickers.ManyDatePickers.onCreateDialog(ManyDatePickers.java:102)
12-18 11:33:00.625: ERROR/AndroidRuntime(1763):     at android.app.Activity.restoreManagedDialogs(Activity.java:857)
12-18 11:33:00.625: ERROR/AndroidRuntime(1763):     at android.app.Activity.performRestoreInstanceState(Activity.java:801)
12-18 11:33:00.625: ERROR/AndroidRuntime(1763):     at android.app.Instrumentation.callActivityOnRestoreInstanceState(Instrumentation.java:1172)
12-18 11:33:00.625: ERROR/AndroidRuntime(1763):     at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2245)
12-18 11:33:00.625: ERROR/AndroidRuntime(1763):     ... 12 more
    
2019-08-16 3 条评论
分享

没有找到相关结果

    已邀请:

    门锑腺潮

    在您的活动中使用此代码： 
    @Override

public void onConfigurationChanged(Configuration newConfig) {
    super.onConfigurationChanged(newConfig);
}
    在清单文件中使用此选项： 
    <activity android:name="MyActivity" android:label="@string/app_name" 
    android:configChanges="orientation|keyboardHidden"></activity>
        
    2019-08-16 0 0
    分享

    闪脖

    Fargath的建议并不是我最害怕的。您的问题是，在配置更改后调用
    onCreateDialog()
    时，
    activateDate
    为空。因为你只在
    onClick()
    中设置一次。你需要在
    onStart()
    中设置它。在
    onResume()
    中设置它将不起作用，但你可能也需要在那里设置它，看看我的问题Android生命周期：在onStart（）或onResume（）？中填写活动中的数据。 如果您想在显示对话框的确切时刻更新日期，那么您可以在
    onPrepareDialog()
    中通过
    updateDate()
    直接进行
    Calendar.getInstance()
    。 Fargath解决方案的问题在于您隐藏了软键盘，但问题仍然存在于具有硬件键盘的设备上，例如G1。来电也是如此。我不确定
    onConfigurationChanged()
    与它有什么关系。     
    2019-08-16 0 0
    分享
    为什么被折叠? 0 个回复被折叠

    要回复问题请先登录或注册

    或代码 OrCode.com 备案号：粤ICP备15020848号-1
    Escape time: 0.048194885253906