android - 如何在android中使用日期和时间选择器，我有什么错误以及如何解决

Question

我正在创建一个使用date and time picker的简单android应用程序，但系统给我一个语法错误，如何解决此错误？

该应用程序允许用户选择日期和时间，而不是将其显示在TextView中

错误是:在if语句 dialogpick 和 timepick 的onclick方法中，错误提示: timepick/dialogpick无法解析为变量

MainActivity.java

package com.example.datetime;

import java.text.DateFormat;
import java.util.Calendar;

import android.os.Bundle;
import android.app.Activity;
import android.app.DatePickerDialog;
import android.app.DatePickerDialog.OnDateSetListener;
import android.app.TimePickerDialog;
import android.view.Menu;
import android.view.View;
import android.view.View.OnClickListener;
import android.widget.Button;
import android.widget.DatePicker;
import android.widget.TextView;
import android.widget.TimePicker;

public class MainActivity extends Activity implements OnClickListener {
    // btn1=time btn2=date
    Button btn1, btn2;
    TextView txtv;
    Calendar cal = Calendar.getInstance();
    DateFormat dt = DateFormat.getDateTimeInstance();

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
        btn1 = (Button) findViewById(R.id.button1);
        btn2 = (Button) findViewById(R.id.button2);
        txtv = (TextView) findViewById(R.id.textView1);
        btn1.setOnClickListener(this);
        btn2.setOnClickListener(this);

        DatePickerDialog.OnDateSetListener dialogpick = new DatePickerDialog.OnDateSetListener() {

            @Override
            public void onDateSet(DatePicker view, int year, int monthofyear,
                    int dayofmonth) {
                // TODO Auto-generated method stub
                cal.set(Calendar.YEAR, year);
                cal.set(Calendar.MONTH, monthofyear);
                cal.set(Calendar.DAY_OF_MONTH, dayofmonth);
                updateText();

            }

            private void updateText() {
                // TODO Auto-generated method stub

            }

        };
        TimePickerDialog.OnTimeSetListener timepick = new TimePickerDialog.OnTimeSetListener() {

            @Override
            public void onTimeSet(TimePicker view, int hourofday, int minute) {
                // TODO Auto-generated method stub
                cal.set(Calendar.HOUR_OF_DAY, hourofday);
                cal.set(Calendar.MINUTE, minute);
                updateText();

            }

            private void updateText() {
                // TODO Auto-generated method stub

            }

        };

    }

    @Override
    public boolean onCreateOptionsMenu(Menu menu) {
        // Inflate the menu; this adds items to the action bar if it is present.
        getMenuInflater().inflate(R.menu.main, menu);
        return true;
    }

    @Override
    public void onClick(View v) {
        // TODO Auto-generated method stub

        if (v.getId() == R.id.button1) {

            new DatePickerDialog(MainActivity.this, dialogpick,
                    cal.get(Calendar.YEAR), cal.get(Calendar.MONTH),
                    cal.get(Calendar.MONDAY)).show();
        } else if (v.getId() == R.id.button2) {
            new TimePickerDialog(MainActivity.this, timepick,
                    cal.get(Calendar.HOUR_OF_DAY), cal.get(Calendar.MINUTE))
                    .show();
        }

    }

}

Answer 1

TimePickerDialog.OnTimeSetListener timepick = new TimePickerDialog.OnTimeSetListener()

timepick是 onCreate()中的局部变量。您不能使用其他方法(例如 onClick())访问局部变量。

您可以将 timepick的声明和实例化移到 onCreate()之外的类成员级别。您可以从所有实例方法访问成员字段。
dialogpick也是如此。