1.返回鍵實現對話方塊彈出是否退出應用程式

package com.example.commondialog;

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

import android.content.DialogInterface;
import android.os.Bundle;

public class MainActivity extends AppCompatActivity {

    @Override
    protected
 
 void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
    }

    @Override
    public void onBackPressed() {
        AlertDialog dialog;
        AlertDialog.Builder builder=new AlertDialog.Builder(this)
                .setTitle(
 
"普通對話方塊")
                .setIcon(R.mipmap.ic_launcher)
                .setMessage("是否確定退出應用：“")
                .setPositiveButton("確定", new DialogInterface.OnClickListener() {
                    @Override
                    public void onClick(DialogInterface dialog,int which) {
                        dialog.dismiss();
                        MainActivity.
 
this.finish();

                    }

                })
                .setNegativeButton("取消", new DialogInterface.OnClickListener() {
                    @Override
                    public void onClick(DialogInterface dialog, int which) {
                        dialog.dismiss();

                    }
                });
        dialog=builder.create();
        dialog.show();
    }
}

2.實現以下場景：從一個activity中點選一個按鈕後，彈出一個單選按鈕對話方塊，上面有“男”“女”兩個選項，選定後，TOAST彈出 你選擇了男，或你選擇了女（參考書上改字型

package com.example.myapplication;



import android.os.Bundle;
import android.app.Activity;
import android.app.AlertDialog;
import android.app.AlertDialog.Builder;
import android.content.DialogInterface;
import android.view.Menu;
import android.view.View;
import android.view.View.OnClickListener;
import android.widget.Button;
import android.widget.Toast;

public class MainActivity extends Activity implements OnClickListener {

    private int num=0;
    private int num1[]={0,1};
    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
        findViewById(R.id.bt).setOnClickListener(this);
    }
    @Override
    public void onClick(View v) {
        // TODO Auto-generated method stub
        AlertDialog.Builder builder=new AlertDialog.Builder(this)
                .setTitle("性別")
                .setSingleChoiceItems(new String[]{"男","女"}, -1, new DialogInterface.OnClickListener() {

                    @Override
                    public void onClick(DialogInterface dialog, int which) {
                        // TODO Auto-generated method stub
                        num=which;
                    }
                })
                .setPositiveButton("確定",new DialogInterface.OnClickListener() {
                    @Override
                    public void onClick(DialogInterface dialog, int which) {
                        // TODO Auto-generated method stub
                        if(num==0){
                            Toast.makeText(MainActivity.this, "你選擇的是男", Toast.LENGTH_LONG).show();
                        }else{
                            Toast.makeText(MainActivity.this, "你選擇的是女", Toast.LENGTH_SHORT).show();
                        }
                        dialog.dismiss();
                    }
                })
                .setNegativeButton("取消", new DialogInterface.OnClickListener() {

                    @Override
                    public void onClick(DialogInterface dialog, int which) {
                        // TODO Auto-generated method stub
                        dialog.dismiss();
                    }
                });
        AlertDialog dialog=builder.create();
        dialog.show();
    }
}

3.佈局(詳見:Android第五週上機word文件)

<?xml version="1.0" encoding="utf-8"?>
<RelativeLayout
    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"
    android:background="#31B404"
    android:layout_margin="2dp"
    tools:context=".MyLayout">
    <TextView
        android:id="@+id/tv_1"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:text="1.TextView顯示文字資訊"
        android:textSize="20sp"
        android:textColor="#FF0000"
        android:textStyle="bold"
        android:gravity="center"
        android:layout_marginTop="10dp"
        />
    <Button
        android:id="@+id/btn_1"
        android:layout_width="350dp"
        android:layout_height="wrap_content"
        android:text="2.按鈕"
        android:textSize="20sp"
        android:textColor="#FF0000"
        android:textStyle="bold"
        android:padding="5dp"
        android:layout_centerHorizontal="true"
        android:layout_below="@+id/tv_1"
        />
    <EditText
        android:id="@+id/et_1"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:hint="3.編輯框：請輸入資訊"
        android:textSize="20sp"
        android:textColorHint="#FF0000"
        android:layout_below="@id/btn_1"
        android:layout_alignStart="@id/btn_1"
        android:layout_margin="5dp"
        />
    <RadioGroup
        android:id="@+id/rg_1"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:orientation="horizontal"
        android:layout_below="@id/et_1"
        android:layout_alignLeft="@id/et_1"
        >
        <RadioButton
            android:id="@+id/rb_1"
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"
            android:text="4.男"
            android:textColor="#FF0000"
            android:textSize="20sp"
            android:textStyle="bold"
            />
        <RadioButton
            android:id="@+id/rb_2"
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"
            android:text="女"
            android:textColor="#FF0000"
            android:textSize="20sp"
            android:textStyle="bold"
            />
        </RadioGroup>
    <LinearLayout
        android:id="@+id/ll_1"
        android:layout_width="match_parent"
        android:layout_height="match_parent"
        android:orientation="vertical"
        android:layout_below="@id/rg_1"
        android:layout_alignLeft="@id/rg_1">
        <CheckBox
            android:id="@+id/cb_1"
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"
            android:text="電腦"
            android:textSize="20sp"
            />
        <CheckBox
            android:id="@+id/cb_2"
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"
            android:text="手機"
            android:textSize="20sp"/>
    </LinearLayout>
</RelativeLayout>

4.教材p76頁 圖3—17購物商城介面

<?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=".MainActivity"
android:orientation="vertical">
<TextView
    android:id="@+id/tv"
    android:layout_width="match_parent"
    android:layout_height="50dp"
    android:text="購物商城"
    android:textColor="#E8E3E9"
    android:background="#E0A9BA"
    android:textSize="20sp"
    android:gravity="center"/>
<ListView
    android:id="@+id/lv"
    android:layout_width="match_parent"
    android:layout_height="wrap_content"/>

</LinearLayout>

<?xml version="1.0" encoding="utf-8"?>
<RelativeLayout 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=".MainActivity">

    <TextView
        android:id="@+id/gouqu"
        android:layout_width="match_parent"
        android:layout_height="50dp"
        android:background="#E91E63"
        android:text="購物商城"
        android:textSize="35sp"
        android:gravity="center"
        />
    <ListView
        android:layout_width="match_parent"
        android:layout_height="match_parent"
        android:id="@+id/lv"
        android:layout_below="@id/gouqu"/>
</RelativeLayout>

<?xml version="1.0" encoding="utf-8"?>
<RelativeLayout
    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=".List_item"
    android:padding="16dp">
    <ImageView
        android:id="@+id/iv"
        android:layout_width="120dp"
        android:layout_height="90dp"
        android:layout_centerVertical="true"/>
    <RelativeLayout
        android:id="@+id/rl_1"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:layout_marginLeft="10dp"
        android:layout_toRightOf="@+id/iv"
        android:layout_centerVertical="true">
    <TextView
        android:id="@+id/title"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:text="桌子"
        android:textColor="#000000"
        android:textSize="20sp"/>
    <TextView
        android:id="@+id/tv_price"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:text="價格"
        android:textColor="#FF8F03"
        android:textSize="20sp"
        android:layout_marginTop="10dp"
        android:layout_below="@id/title"/>
    <TextView
        android:id="@+id/price"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:text="1000"
        android:textSize="20sp"
        android:textColor="#FF8F03"
        android:layout_toRightOf="@id/tv_price"
        android:layout_marginTop="10dp"
        android:layout_below="@+id/title"/>
    </RelativeLayout>
</RelativeLayout>