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1. AlertDialog

AlertDialog是弹出的提醒对话框，有提示，确认，选择等功能。

没有公开的构造方法，一般用AlertDialog.Builder来完成参数设置，最后调用create方法创建。

参数设置常用的方法：

 代码：

package com.example.ch3;import androidx.appcompat.app.AppCompatActivity;import android.app.AlertDialog;
import android.app.Dialog;
import android.content.DialogInterface;
import android.os.Bundle;
import android.view.View;
import android.widget.TextView;public class AlertDialogActivity extends AppCompatActivity implements View.OnClickListener {private TextView tv;@Overrideprotected void onCreate(Bundle savedInstanceState) {super.onCreate(savedInstanceState);setContentView(R.layout.activity_alert_dialog);findViewById(R.id.bt).setOnClickListener(this);tv = findViewById(R.id.tv);}@Overridepublic void onClick(View view) {AlertDialog.Builder builder = new AlertDialog.Builder(this);builder.setTitle("Dear customer");builder.setMessage("Do you want to download this file?");builder.setNegativeButton("No, thanks", new DialogInterface.OnClickListener() {@Overridepublic void onClick(DialogInterface dialogInterface, int i) {tv.setText("Cancel download file");}});builder.setPositiveButton("Yes", new DialogInterface.OnClickListener() {@Overridepublic void onClick(DialogInterface dialogInterface, int i) {tv.setText("Downloading file...");}});AlertDialog dialog = builder.create();dialog.show();}
}

效果图：

 

2. DatePickerDialog

DatePickerDialog在 AlertDialog上添加了日期选择器DatePicker，达到日期选择弹窗的目的。

先来看一下日期选择器DatePicker的使用：

<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"xmlns:app="http://schemas.android.com/apk/res-auto"xmlns:tools="http://schemas.android.com/tools"android:layout_width="match_parent"android:layout_height="match_parent"tools:context=".DatePickerDialogActivity"android:orientation="vertical"android:gravity="center_horizontal"><DatePickerandroid:id="@+id/dp"android:layout_width="wrap_content"android:layout_height="wrap_content"android:datePickerMode="spinner"android:calendarViewShown="false"></DatePicker><Buttonandroid:id="@+id/bt"android:layout_width="match_parent"android:layout_height="wrap_content"android:text="Confirm"></Button><TextViewandroid:id="@+id/tv"android:layout_width="match_parent"android:layout_height="wrap_content"></TextView>
</LinearLayout>

datePickerMode可以选"spinner"或者"calendar"
spinner同时显示日期选择滑动窗口和日历，可以用calendarViewShown关掉日历
calendar只显示日历

 java代码：

package com.example.ch3;import androidx.appcompat.app.AppCompatActivity;import android.os.Bundle;
import android.view.View;
import android.widget.Button;
import android.widget.DatePicker;
import android.widget.TextView;public class DatePickerDialogActivity extends AppCompatActivity implements View.OnClickListener {private DatePicker dp;private TextView tv;@Overrideprotected void onCreate(Bundle savedInstanceState) {super.onCreate(savedInstanceState);setContentView(R.layout.activity_date_picker_dialog);findViewById(R.id.bt).setOnClickListener(this);dp = findViewById(R.id.dp);tv = findViewById(R.id.tv);}@Overridepublic void onClick(View view) {String s = String.format("You choose  %d/%d/%d", dp.getYear(),dp.getMonth()+1,  dp.getDayOfMonth());tv.setText(s);}
}

效果图：

DatePickerDialog则是内置了日期选择器的弹窗，用onDateSet方法设置确定日期之后的动作。

代码：

package com.example.ch3;import androidx.appcompat.app.AppCompatActivity;import android.app.DatePickerDialog;
import android.os.Bundle;
import android.view.View;
import android.widget.Button;
import android.widget.DatePicker;
import android.widget.TextView;public class DatePickerDialogActivity extends AppCompatActivity implements View.OnClickListener, DatePickerDialog.OnDateSetListener {private DatePicker dp;private TextView tv;@Overrideprotected void onCreate(Bundle savedInstanceState) {super.onCreate(savedInstanceState);setContentView(R.layout.activity_date_picker_dialog);findViewById(R.id.bt).setOnClickListener(this);findViewById(R.id.bt_date).setOnClickListener(this);dp = findViewById(R.id.dp);tv = findViewById(R.id.tv);}@Overridepublic void onClick(View view) {switch(view.getId()){case R.id.bt:String s = String.format("You choose  %d/%d/%d", dp.getYear(),dp.getMonth()+1,  dp.getDayOfMonth());tv.setText(s);break;case R.id.bt_date:DatePickerDialog datePickerDialog = new DatePickerDialog(this,this,2000,1,1);datePickerDialog.show();break;}}@Overridepublic void onDateSet(DatePicker dp, int i, int i1, int i2) {String s = String.format("You choose  %d/%d/%d", dp.getYear(),dp.getMonth()+1,  dp.getDayOfMonth());tv.setText(s);}
}

 

效果图：

3.TimePickerDialog

TimePickerDialog和DatePickerDialog原理类似，内置了时间选择器TimePicker。

xml代码：

<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"xmlns:app="http://schemas.android.com/apk/res-auto"xmlns:tools="http://schemas.android.com/tools"android:layout_width="match_parent"android:layout_height="match_parent"tools:context=".DatePickerDialogActivity"android:orientation="vertical"android:gravity="center_horizontal"><TimePickerandroid:id="@+id/tp"android:layout_width="wrap_content"android:layout_height="wrap_content"android:timePickerMode="spinner"></TimePicker><Buttonandroid:id="@+id/bt"android:layout_width="match_parent"android:layout_height="wrap_content"android:text="Confirm"></Button><TextViewandroid:id="@+id/tv"android:layout_width="match_parent"android:layout_height="wrap_content"></TextView><Buttonandroid:id="@+id/bt_time"android:layout_marginTop="50dp"android:layout_width="match_parent"android:layout_height="wrap_content"android:text="Choose Time"></Button>
</LinearLayout>

 

java代码：

package com.example.ch3;import androidx.appcompat.app.AppCompatActivity;import android.app.TimePickerDialog;
import android.os.Bundle;
import android.view.View;
import android.widget.TextView;
import android.widget.TimePicker;import java.util.Calendar;public class TimePickerActivity extends AppCompatActivity implements View.OnClickListener, TimePickerDialog.OnTimeSetListener {private TextView tv;private TimePicker tp;@Overrideprotected void onCreate(Bundle savedInstanceState) {super.onCreate(savedInstanceState);setContentView(R.layout.activity_time_picker);findViewById(R.id.bt).setOnClickListener(this);findViewById(R.id.bt_time).setOnClickListener(this);tv = findViewById(R.id.tv);tp = findViewById(R.id.tp);}@Overridepublic void onClick(View view) {switch (view.getId()){case R.id.bt:String s = String.format("You choose %d/%d",tp.getHour(), tp.getMinute());tv.setText(s);break;case R.id.bt_time:Calendar calendar =Calendar.getInstance();TimePickerDialog timePickerDialog = new TimePickerDialog(this, this,calendar.get(Calendar.HOUR_OF_DAY),calendar.get(Calendar.MINUTE),true);timePickerDialog.show();}}@Overridepublic void onTimeSet(TimePicker timePicker, int i, int i1) {String s = String.format("You choose %d/%d",i, i1);tv.setText(s);}
}

效果图：