Android学习05

AlertDialog（对话框）

      它也是其他 Dialog的的父类！比如ProgressDialog，TimePickerDialog等，而AlertDialog的父类是：Dialog！

      AlertDialog并不能直接new出来，构造方法是protected的，要创建AlertDialog的话，需要使用到该类中的一个静态内部类：public static class Builder，然后来调用AlertDialog 里的相关方法，来对AlertDialog进行定制，最后调用show()方法来显示AlertDialog对话框！

      AlertDialog有几个基本方法，

      例如：setTitile() setMessage() setCancelable() setPositiveButton() setNegativeButton() setNeutralButton() 等等。

1、带按钮的AlertDialog

点击按钮弹出提示内容；

public void onClick(View v) {
            switch (v.getId()) {
                case R.id.btn_dialog1:
                    AlertDialog.Builder builder = new AlertDialog.Builder(DialogActivity.this);
                    builder.setTitle("请回答").setMessage("想见你会加更吗？")
                            .setPositiveButton("会", new DialogInterface.OnClickListener() {
                                @Override
                                public void onClick(DialogInterface dialog, int which) {
                                    Toast.makeText(DialogActivity.this, "你点击了会", Toast.LENGTH_SHORT).show();
                                }
                            }).setNegativeButton("不会", new DialogInterface.OnClickListener() {
                        @Override
                        public void onClick(DialogInterface dialog, int which) {
                            Toast.makeText(DialogActivity.this, "你点击了不会", Toast.LENGTH_SHORT).show();
                        }
                    }).show();
                    break;

2.1、类似RadioButton的AlertDialog，单选

case R.id.btn_dialog2:
                    final String[] array2 = new String[]{"男", "女"};
                    AlertDialog.Builder builder2 = new AlertDialog.Builder(DialogActivity.this);
                    builder2.setTitle("选择性别").setItems(array2, new DialogInterface.OnClickListener() {
                        @Override
                        public void onClick(DialogInterface dialog, int which) {
                            Toast.makeText(DialogActivity.this, array2[which], Toast.LENGTH_SHORT).show();
                        }
                    }).show();
                    break;

2.2、与RadioButton一样的AlertDialog

case R.id.btn_dialog3:
                    final String[] array3 = new String[]{"男", "女"};
                    AlertDialog.Builder builder3 = new AlertDialog.Builder(DialogActivity.this);
                    builder3.setTitle("选择性别").setSingleChoiceItems(array3, 0, new DialogInterface.OnClickListener() {
                        @Override                                                     //默认选中第几个
                        public void onClick(DialogInterface dialog, int which) {
                            Toast.makeText(DialogActivity.this, array3[which], Toast.LENGTH_SHORT).show();
                            //选择之后对话框会消失
                            dialog.dismiss();
                        }//点框外对话框不会消失
                    }).setCancelable(false).show();
                    break;

3、与CheckBox一样的AlertDialog

case R.id.btn_dialog4:
                    final String[] array4 = new String[]{"唱", "跳","rap"};
                    boolean[] isSelected = new boolean[]{false,false,true};
                    AlertDialog.Builder builder4 = new AlertDialog.Builder(DialogActivity.this);
                    builder4.setTitle("选择兴趣").setMultiChoiceItems(array4, isSelected, new DialogInterface.OnMultiChoiceClickListener() {
                        @Override
                        public void onClick(DialogInterface dialog, int which, boolean isChecked) {
                            //which表示当前选中第几个，isChecked表示选中或取消选中
                            Toast.makeText(DialogActivity.this, array4[which]+":"+isChecked, Toast.LENGTH_SHORT).show();
                        }
                    }).setPositiveButton("确定", new DialogInterface.OnClickListener() {
                        @Override
                        public void onClick(DialogInterface dialog, int which) {
                            //
                        }
                    }).setNegativeButton("取消", new DialogInterface.OnClickListener() {
                        @Override
                        public void onClick(DialogInterface dialog, int which) {
                            //
                        }
                    }).show();
                    break;

4、自定义View的AlertDialog

要实现一个Login画面，有用户名和密码，这时我们就要用到自定义View的AlertDialog，步骤如下：

• 先创建自定义登录框的布局文件layout_dialog.xml
• 在Activity中创建自定义的AlertDialog

 layout_dialog.xml：

<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
    android:orientation="vertical"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:padding="15dp">

    <EditText
        android:id="@+id/et_username"
        android:layout_width="match_parent"
        android:layout_height="50dp"
        android:textSize="15sp"
        android:textColor="#FF8F44"
        android:background="@drawable/bg_username"
        android:hint="用户名"
        android:paddingLeft="10dp"
        android:paddingRight="10dp"/>

    <EditText
        android:id="@+id/et_password"
        android:layout_width="match_parent"
        android:layout_height="50dp"
        android:textSize="15sp"
        android:textColor="#FF8F44"
        android:layout_below="@id/edit_1"
        android:background="@drawable/bg_username"
        android:hint="密码"
        android:inputType="textPassword"
        android:layout_marginTop="15dp"
        android:paddingLeft="10dp"
        android:paddingRight="10dp"/>

    <Button
        android:id="@+id/btn_login"
        android:layout_width="match_parent"
        android:layout_height="50dp"
        android:layout_below="@id/edit_2"
        android:layout_marginTop="20dp"
        android:background="@drawable/bg_btn4"
        android:text="登录"
        android:textSize="20sp"
        android:textColor="#fff"/>
</LinearLayout>

Activity：

case R.id.btn_dialog5:
                    AlertDialog.Builder builder5 = new AlertDialog.Builder(DialogActivity.this);
                    View view = LayoutInflater.from(DialogActivity.this).inflate(R.layout.layout_dialog,null);
                    //声明布局里的控件
                    EditText etUsername = view.findViewById(R.id.et_username);
                    EditText etPassword = view.findViewById(R.id.et_password);
                    Button btnLogin = view.findViewById(R.id.btn_login);
                    btnLogin.setOnClickListener(new View.OnClickListener() {
                        @Override
                        public void onClick(View v) {
                            //
                        }
                    });
                    builder5.setTitle("请登录").setView(view).show();
                    break;

完整代码：

DialogActivity：

package com.example.helloworld;

import androidx.appcompat.app.AlertDialog;
import androidx.appcompat.app.AppCompatActivity;

import android.content.DialogInterface;
import android.content.Intent;
import android.os.Bundle;
import android.view.LayoutInflater;
import android.view.View;
import android.widget.Button;
import android.widget.EditText;
import android.widget.Toast;

public class DialogActivity extends AppCompatActivity {

    private Button mBtnDialog1, mBtnDialog2, mBtnDialog3, mBtnDialog4,mBtnDialog5;

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_dialog);
        mBtnDialog1 = findViewById(R.id.btn_dialog1);
        mBtnDialog2 = findViewById(R.id.btn_dialog2);
        mBtnDialog3 = findViewById(R.id.btn_dialog3);
        mBtnDialog4 = findViewById(R.id.btn_dialog4);
        mBtnDialog5 = findViewById(R.id.btn_dialog5);
        onClick onClick = new onClick();
        mBtnDialog1.setOnClickListener(onClick);
        mBtnDialog2.setOnClickListener(onClick);
        mBtnDialog3.setOnClickListener(onClick);
        mBtnDialog4.setOnClickListener(onClick);
        mBtnDialog5.setOnClickListener(onClick);
    }

    class onClick implements View.OnClickListener {
        @Override
        public void onClick(View v) {
            switch (v.getId()) {
                case R.id.btn_dialog1:
                    AlertDialog.Builder builder = new AlertDialog.Builder(DialogActivity.this);
                    builder.setTitle("请回答").setMessage("想见你会加更吗？")
                            .setPositiveButton("会", new DialogInterface.OnClickListener() {
                                @Override
                                public void onClick(DialogInterface dialog, int which) {
                                    Toast.makeText(DialogActivity.this, "你点击了会", Toast.LENGTH_SHORT).show();
                                }
                            }).setNegativeButton("不会", new DialogInterface.OnClickListener() {
                        @Override
                        public void onClick(DialogInterface dialog, int which) {
                            Toast.makeText(DialogActivity.this, "你点击了不会", Toast.LENGTH_SHORT).show();
                        }
                    }).show();
                    break;
                case R.id.btn_dialog2:
                    final String[] array2 = new String[]{"男", "女"};
                    AlertDialog.Builder builder2 = new AlertDialog.Builder(DialogActivity.this);
                    builder2.setTitle("选择性别").setItems(array2, new DialogInterface.OnClickListener() {
                        @Override
                        public void onClick(DialogInterface dialog, int which) {
                            Toast.makeText(DialogActivity.this, array2[which], Toast.LENGTH_SHORT).show();
                        }
                    }).show();
                    break;
                case R.id.btn_dialog3:
                    final String[] array3 = new String[]{"男", "女"};
                    AlertDialog.Builder builder3 = new AlertDialog.Builder(DialogActivity.this);
                    builder3.setTitle("选择性别").setSingleChoiceItems(array3, 0, new DialogInterface.OnClickListener() {
                        @Override                                                     //默认选中第几个
                        public void onClick(DialogInterface dialog, int which) {
                            Toast.makeText(DialogActivity.this, array3[which], Toast.LENGTH_SHORT).show();
                            //选择之后对话框会消失
                            dialog.dismiss();
                        }//点框外对话框不会消失
                    }).setCancelable(false).show();
                    break;
                case R.id.btn_dialog4:
                    final String[] array4 = new String[]{"唱", "跳","rap"};
                    boolean[] isSelected = new boolean[]{false,false,true};
                    AlertDialog.Builder builder4 = new AlertDialog.Builder(DialogActivity.this);
                    builder4.setTitle("选择兴趣").setMultiChoiceItems(array4, isSelected, new DialogInterface.OnMultiChoiceClickListener() {
                        @Override
                        public void onClick(DialogInterface dialog, int which, boolean isChecked) {
                            //which表示当前选中第几个，isChecked表示选中或取消选中
                            Toast.makeText(DialogActivity.this, array4[which]+":"+isChecked, Toast.LENGTH_SHORT).show();
                        }
                    }).setPositiveButton("确定", new DialogInterface.OnClickListener() {
                        @Override
                        public void onClick(DialogInterface dialog, int which) {
                            //
                        }
                    }).setNegativeButton("取消", new DialogInterface.OnClickListener() {
                        @Override
                        public void onClick(DialogInterface dialog, int which) {
                            //
                        }
                    }).show();
                    break;
                case R.id.btn_dialog5:
                    AlertDialog.Builder builder5 = new AlertDialog.Builder(DialogActivity.this);
                    View view = LayoutInflater.from(DialogActivity.this).inflate(R.layout.layout_dialog,null);
                    //声明布局里的控件
                    EditText etUsername = view.findViewById(R.id.et_username);
                    EditText etPassword = view.findViewById(R.id.et_password);
                    Button btnLogin = view.findViewById(R.id.btn_login);
                    btnLogin.setOnClickListener(new View.OnClickListener() {
                        @Override
                        public void onClick(View v) {
                            //
                        }
                    });
                    builder5.setTitle("请登录").setView(view).show();
                    break;

            }
        }
    }

}

activity_edit_text.xml：

<?xml version="1.0" encoding="utf-8"?>
<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:padding="15dp">
    <EditText
        android:id="@+id/edit_1"
        android:layout_width="match_parent"
        android:layout_height="50dp"
        android:textSize="15sp"
        android:textColor="#FF8F44"
        android:background="@drawable/bg_username"
        android:hint="用户名"
        android:paddingLeft="10dp"
        android:paddingRight="10dp"/>

    <EditText
        android:id="@+id/edit_2"
        android:layout_width="match_parent"
        android:layout_height="50dp"
        android:textSize="15sp"
        android:textColor="#FF8F44"
        android:layout_below="@id/edit_1"
        android:background="@drawable/bg_username"
        android:hint="密码"
        android:inputType="textPassword"
        android:layout_marginTop="15dp"
        android:paddingLeft="10dp"
        android:paddingRight="10dp"/>

    <Button
        android:id="@+id/btn_login"
        android:layout_width="match_parent"
        android:layout_height="50dp"
        android:layout_below="@id/edit_2"
        android:layout_marginTop="20dp"
        android:background="@drawable/bg_btn4"
        android:text="登录"
        android:textSize="20sp"
        android:textColor="#fff"/>
</RelativeLayout>