设置时间时java.lang.NullPointerException

Question

TimePicker出现了，但是当我尝试选择时间时。 这使我感到异常。

TimeFragment类。

import java.util.Calendar;
import com.actionbarsherlock.app.SherlockDialogFragment;
import android.app.Dialog;
import android.app.TimePickerDialog;
import android.content.Context;
import android.os.Bundle;
import android.text.format.DateFormat;
import android.widget.TimePicker;

public class TimePickerFragment extends SherlockDialogFragment implements TimePickerDialog.OnTimeSetListener
{
    private TimePickedListener mListener;
    static int hour;
    static int minute;
    static Context mContext;

    public static TimePickerFragment newInstance(Context context, TimePickedListener listener, Calendar now)
    {
        TimePickerFragment dialog = new TimePickerFragment();
        mContext = context;
        hour = now.get(Calendar.HOUR_OF_DAY);
        minute = now.get(Calendar.MINUTE);

        return dialog;
    }

    @Override
    public Dialog onCreateDialog(Bundle savedInstanceState)
    {
        return new TimePickerDialog(mContext, this, hour, minute, DateFormat.is24HourFormat(getActivity()));
    }

    @Override
    public void onTimeSet(TimePicker view, int hourOfDay, int minute)
    {
        // when the time is selected, send it to the activity via its callback
        // interface method
        Calendar c = Calendar.getInstance();
        c.set(Calendar.HOUR_OF_DAY, hourOfDay);
        c.set(Calendar.MINUTE, minute);

        mListener.onTimePicked(c);
    }

    public static interface TimePickedListener
    {
        public void onTimePicked(Calendar time);
    }
}

在主片段中选择时间

public void selectTime(final TextView lblTime, final int position) {
    hideRight();
    timeFrag = TimePickerFragment.newInstance(getActivity(), new TimePickedListener() {@
        Override
        public void onTimePicked(Calendar time) {
            lblTime.setText(DateFormat.format("h:mm a", time));
        }
    }, now);
    timeFrag.show(getActivity().getSupportFragmentManager(), "timePicker");
}

07-02 17：28：04.214：E / XXX（10341）：未捕获的异常是：07-02 17：28：04.214：E / XXX（10341）：java.lang.NullPointerException 07-02 17：28：04.214： E / XXX（10341）：位于com.common.TimePickerFragment.onTimeSet（TimePickerFragment.java:47）07-02 17：28：04.214：E / XXX（10341）：位于android.app.TimePickerDialog.tryNotifyTimeSet（TimePickerDialog.java ：130）07-02 17：28：04.214：E / XXX（10341）：在android.app.TimePickerDialog.onClick（TimePickerDialog.java:115）07-02 17：28：04.214：E / XXX（10341）：在com.android.internal.app.AlertController $ ButtonHandler.handleMessage（AlertController.java:166）07-02 17：28：04.214：E / XXX（10341）：在android.os.Handler.dispatchMessage（Handler.java： 99）07-02 17：28：04.214：E / XXX（10341）：at android.os.Looper.loop（Looper.java:137）07-02 17：28：04.214：E / XXX（10341）：at android.app.ActivityThread.main（ActivityThread.java:4928）07-02 17：28：04.214：E / XXX（10341）：at java.lang.reflect.Method.invokeNative（Native Method）07-02 17:28 ：04.214：E / XXX（10341）：at java.lang.reflect.Method.invoke（Method.jav a：511）07-02 17：28：04.214：E / XXX（10341）：在com.android.internal.os.ZygoteInit $ MethodAndArgsCaller.run（ZygoteInit.java:791）07-02 17：28：04.214： E / XXX（10341）：在com.android.internal.os.ZygoteInit.main（ZygoteInit.java:558）07-02 17：28：04.214：E / XXX（10341）：在dalvik.system.NativeStart.main （本机方法）

Answer 1

您忘记初始化private TimePickedListener mListener;

使用以下命令更改newInstance方法：

public static TimePickerFragment newInstance(Context context, TimePickedListener listener, Calendar now)
    {
        TimePickerFragment dialog = new TimePickerFragment();
        mContext = context;
        mListener = listener;
        hour = now.get(Calendar.HOUR_OF_DAY);
        minute = now.get(Calendar.MINUTE);

        return dialog;
    }

Answer 2

您没有实例化private TimePickedListener mListener; 任何地方。 它引用null 。

public static TimePickerFragment newInstance(Context context, TimePickedListener listener, Calendar now)
{
    TimePickerFragment dialog = new TimePickerFragment();
    mContext = context;
    hour = now.get(Calendar.HOUR_OF_DAY);
    minute = now.get(Calendar.MINUTE);
    mListener = listener; // you missed this line
    return dialog;
}