Android (3) DatePickerDialog 選擇日期

1. 添加一個 Button 和 TextView：

<LinearLayout
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:orientation="vertical" >
    <TextView
        android:id="@+id/dateText"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:hint="Date"
        android:textSize="30sp"/>
    <Button
        android:id="@+id/dateButton"        
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:text="Date" />
</LinearLayout>

Button 用來選擇日期，TextView 用來顯示資料。

2. Source code：

先在原本的程式中找到我們的物件，並幫 Button 註冊一個 Listener。

public class MainActivity extends AppCompatActivity {
    @Override
    public void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);

        final TextView dateText = (TextView)findViewById(R.id.dateText);
        final Button dateButton = (Button)findViewById(R.id.dateButton);
        dateButton.setOnClickListener(new MyDatePicker(dateText));
    }
}

Listener 實做 OnClickListener 和 OnDateSetListener 的方法。 按下按鍵時會跳出可以選擇的日曆，選擇完日期後會觸發更新。

private class MyDatePicker implements View.OnClickListener, DatePickerDialog.OnDateSetListener {
    private TextView mDateText;

    public MyDatePicker(TextView dateText) {
        mDateText = dateText;
    }

    @Override
    public void onClick(View v) {
        Calendar calendar = Calendar.getInstance();

        DatePickerDialog dialog = new DatePickerDialog(
                MainActivity.this,  // context
                this,               // listener
                calendar.get(Calendar.YEAR),
                calendar.get(Calendar.MONTH),
                calendar.get(Calendar.DAY_OF_MONTH));
        dialog.show();
    }

    @Override
    public void onDateSet(android.widget.DatePicker view, int year, int month, int day) {
        String des = String.format("%s-%s-%s", year, month, day);
        mDateText.setText(des);
    }
}

3. 完整程式碼：

package com.example.ben.androidtest;

import android.app.DatePickerDialog;
import android.icu.util.Calendar;
import android.support.v7.app.AppCompatActivity;
import android.os.Bundle;
import android.view.View;
import android.widget.Button;
import android.widget.TextView;

public class MainActivity extends AppCompatActivity {
    @Override
    public void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);

        final TextView dateText = (TextView)findViewById(R.id.dateText);
        final Button dateButton = (Button)findViewById(R.id.dateButton);
        dateButton.setOnClickListener(new MyDatePicker(dateText));
    }

    private class MyDatePicker implements View.OnClickListener, DatePickerDialog.OnDateSetListener {
        private TextView mDateText;

        public MyDatePicker(TextView dateText) {
            mDateText = dateText;
        }

        @Override
        public void onClick(View v) {
            Calendar calendar = Calendar.getInstance();

            DatePickerDialog dialog = new DatePickerDialog(
                    MainActivity.this,
                    this,
                    calendar.get(Calendar.YEAR),
                    calendar.get(Calendar.MONTH),
                    calendar.get(Calendar.DAY_OF_MONTH));
            dialog.show();
        }

        @Override
        public void onDateSet(android.widget.DatePicker view, int year, int month, int day) {
            String des = String.format("%s-%s-%s", year, month, day);
            mDateText.setText(des);
        }
    }
}