<Android 基础（十五）> Alert Dialog

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介绍

The AlertDialog class allows you to build a variety of dialog designs and is often the only dialog class you’ll need. there are three regions of an alert dialog:

1.Title
This is optional and should be used only when the content area is occupied by a detailed message, a list, or custom layout. If you need to state a simple message or question (such as the dialog in figure 1), you don’t need a title.

2.Content area
This can display a message, a list, or other custom layout.

3.Action buttons
There should be no more than three action buttons in a dialog.

一般的AlertDialog分为2个部分，头部，内容和Action Button，头部包含图标和文字，内容部分可以自定义，也可以使用一些常见的列表，单选项，多选项等内容，Action Button就是常见的OK啊， Cancel啊等等。

类结构

AlertDialog
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重点关注一下Builder类的结构
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关于这些方法的使用说明，这里不做一一介绍，后面通过实例可以看出端倪，不过可以通过查阅API文档熟悉一下，AlertDialog.Builder

实际使用

Simple AlertDialog

代码使用

    private void showSimpleAlertDialog() {        //创建alertdialog builder        AlertDialog.Builder builder = new AlertDialog.Builder(mContext);        //设置图标，标题，消息内容        builder.setIcon(getResources().getDrawable(R.drawable.ic_adb_black_24dp))                .setTitle(R.string.title)                .setMessage(R.string.content);        //设置Acton Buttons        builder.setNegativeButton(R.string.cancel, new DialogInterface.OnClickListener() {            @Override            public void onClick(DialogInterface dialogInterface, int i) {                Toast.makeText(mContext, "Cancal is clicked", Toast.LENGTH_SHORT).show();            }        });        builder.setPositiveButton(R.string.ok, new DialogInterface.OnClickListener() {            @Override            public void onClick(DialogInterface dialogInterface, int i) {                Toast.makeText(mContext, "OK is clicked", Toast.LENGTH_SHORT).show();            }        });        builder.setNeutralButton(R.string.reminder, new DialogInterface.OnClickListener() {            @Override            public void onClick(DialogInterface dialogInterface, int i) {                Toast.makeText(mContext, "Remind me later is clicked", Toast.LENGTH_SHORT).show();            }        });        //显示alert dialog  这个是AlertDialog的show()方法是等价的        builder.show();    }

效果
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备注

Action Button 意义 setNegativeButton 做取消、返回等操作，如Cancel setPositiveButton 做确认、提交等操作，如OK setNeutralButton 做中性操作，如Update Later

AlertDialog.Builder中的show()方法和AlertDialog的show()方法是等价的

AlertDialog With Array

代码使用

    public void showAlertDialogWithArray() {        AlertDialog.Builder builder = new AlertDialog.Builder(mContext);        builder.setIcon(getResources().getDrawable(R.drawable.ic_assessment_black_24dp))                .setTitle(R.string.title)                .setItems(R.array.dialoglist, new DialogInterface.OnClickListener() {                    @Override                    public void onClick(DialogInterface dialogInterface, int i) {                        switch (i) {                            case 0:                                showTwo.setBackgroundResource(R.color.pink);                                break;                            case 1:                                showTwo.setBackgroundResource(R.color.stone);                                break;                            case 2:                                showTwo.setBackgroundResource(R.color.yellow);                                break;                        }                    }                });        builder.create().show();    }

效果
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备注

方法 setItems 通过array来设置dialog的内容 setAdapter 通过ListAdapter来设置dialog的内容

ListAdapter可以显示的内容应该比Array要丰富，但是现在开源库很多，针对Dialog的美观的开源库也不少，一般开发过程中会使用现成的。

AlertDialog With MultiChoice

代码使用

    public void showAlertDialogWithMutiChoice() {        final ArrayList<String> selecteditems = new ArrayList<>();        AlertDialog.Builder builder = new AlertDialog.Builder(mContext);        builder.setIcon(R.drawable.ic_event_seat_black_24dp)                .setTitle(R.string.title)                .setMultiChoiceItems(R.array.fruits, null,                         new DialogInterface.OnMultiChoiceClickListener() {                    @Override                    public void onClick(DialogInterface dialogInterface, int which,                                         boolean isChecked) {                        if (isChecked) {                            selecteditems.add(getResources()                                    .getStringArray(R.array.fruits)[which]);                            Toast.makeText(mContext, selecteditems.toString(), Toast.LENGTH_SHORT).show();                        } else {                            selecteditems.remove(getResources()                                    .getStringArray(R.array.fruits)[which]);                            Toast.makeText(mContext, selecteditems.toString(), Toast.LENGTH_SHORT).show();                        }                    }                });        builder.create().show();    }

效果
这里写图片描述

AlertDialog With Single Choice

代码使用

    public void showAlertDialogWithSingleChoice() {        AlertDialog.Builder builder = new AlertDialog.Builder(mContext);        builder.setIcon(R.drawable.ic_build_black_24dp)                .setTitle(R.string.title);        builder.setSingleChoiceItems(R.array.places, -1,                new DialogInterface.OnClickListener() {            @Override            public void onClick(DialogInterface dialogInterface, int i) {                Toast.makeText(mContext,                         getResources().getStringArray(R.array.places)[i] + " is selected",                         Toast.LENGTH_SHORT).show();            }        });        builder.create().show();    }

效果
这里写图片描述

Custom Alert Dialog

代码使用

    public void showCustomAlertDialog() {        AlertDialog.Builder builder = new AlertDialog.Builder(mContext);        builder.setIcon(R.drawable.ic_assessment_black_24dp).setTitle(R.string.login);        builder.setView(R.layout.custom_alert);        builder.setCustomTitle(LayoutInflater.from(mContext).inflate(R.layout.custom_title , null ));        builder.create().show();    }

自定义布局文件

Title自定义

<?xml version="1.0" encoding="utf-8"?><LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"    android:layout_width="match_parent"    android:layout_height="60dp"    android:background="@drawable/shape_title"    android:orientation="horizontal">    <ImageView        android:layout_width="60dp"        android:layout_height="60dp"        android:paddingLeft="20dp"        android:src="@drawable/ic_adb_black_24dp" />    <TextView        android:layout_width="wrap_content"        android:layout_height="wrap_content"        android:layout_gravity="center_vertical"        android:layout_marginLeft="40dp"        android:text="Custom Title"        android:textSize="15pt"        android:textStyle="bold" /></LinearLayout>

Content Area自定义

<?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"    android:layout_width="match_parent"    android:layout_height="match_parent"    android:layout_margin="@dimen/activity_horizontal_margin"    android:orientation="vertical">    <android.support.design.widget.TextInputLayout        android:layout_width="match_parent"        android:layout_height="wrap_content"        android:layout_marginTop="10dp">        <EditText            android:layout_width="match_parent"            android:layout_height="wrap_content"            android:hint="UserName" />    </android.support.design.widget.TextInputLayout>    <android.support.design.widget.TextInputLayout        android:layout_width="match_parent"        android:layout_height="wrap_content"        app:counterEnabled="true"        app:counterMaxLength="40">        <EditText            android:layout_width="match_parent"            android:layout_height="wrap_content"            android:fontFamily="sans-serif"            android:hint="Password"            android:inputType="textPassword" />    </android.support.design.widget.TextInputLayout>    <LinearLayout        android:layout_width="match_parent"        android:layout_height="wrap_content"        android:layout_margin="@dimen/activity_vertical_margin"        android:orientation="horizontal">        <Button            android:layout_width="wrap_content"            android:layout_height="match_parent"            android:layout_weight="1"            android:background="@drawable/shaperect"            android:text="Submit" />        <Button            android:layout_width="wrap_content"            android:layout_height="match_parent"            android:layout_weight="1"            android:background="@drawable/shape_two"            android:text="Reset" />    </LinearLayout></LinearLayout>

效果

这里写图片描述

备注

自定义标题栏和显示的内容，Action Button可以通过在Content中添加Button的方式来实现，丰富了Alert Dialog的显示内容，Alert Dialog中应该还有很多东西待挖掘，锄头需要挥起来~

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