Android第五六周作业

1.返回键实现对话框弹出是否退出应用程序

package com.example.zuoye1;

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

import android.annotation.SuppressLint;
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(){
        //声明对象
        AlertDialog dialog;
        AlertDialog.Builder builder=new AlertDialog.Builder(this)
                .setTitle("普通对话框")//设置对话框的标题
        .setIcon(R.mipmap.ic_launcher)//设置设置标题图标
        .setMessage("是否确定退出应用：")//设置对话框的提示信息
        //添加‘确定’按钮
        .setPositiveButton("确定", new DialogInterface.OnClickListener() {
            @Override
            public void onClick(DialogInterface dialog, int which) {
                dialog.dismiss();//关闭对话框
                MainActivity.this.finish();//关闭MainActivity
            }
        })//添加“取消”按钮
        .setNegativeButton("取消", new DialogInterface.OnClickListener() {
            @Override
            public void onClick(DialogInterface dialog, int which) {
                dialog.dismiss();
            }
        });
        dialog =builder.create();
        dialog.show();

    }
}

2.实现以下场景：从一个activity中点击一个按钮后，弹出一个单选按钮对话框，上面有“男”“女”两个选项，选定后，TOAST弹出 你选择了男，或你选择了女（参考书上改字体）

<?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"
    android:orientation="vertical"
    tools:ignore="MissingConstraints"
    >

    <TextView
        android:id="@+id/v1"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:gravity="center"
        android:text="请选择性别:"
        android:layout_marginTop="10dp"
        android:textSize="20sp"
        android:textColor="#FFC0CB"/>

    <Button
        android:id="@+id/v2"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:text="选择性别"
        android:layout_marginTop="20dp"
        android:layout_gravity="center" />

</LinearLayout>

package com.example.zuoye;

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

import android.content.DialogInterface;
import android.net.Uri;
import android.os.Bundle;
import android.view.View;
import android.widget.TextView;

public class MainActivity extends AppCompatActivity implements View.OnClickListener{
private TextView textView;
private int[] textSizeArr = {10,20};
int textSize =1;
    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
        //设置Button监听事件
        findViewById(R.id.v2).setOnClickListener(this);
        textView=(TextView) findViewById(R.id.v1);
    }
    @Override
    public void onClick(View v){
        AlertDialog dialog;
        AlertDialog.Builder builder=new AlertDialog.Builder(this)
                .setTitle("设置字体大小")//设置标题
        .setIcon(R.mipmap.ic_launcher)
                .setSingleChoiceItems(new String[]{"男","女"},textSize,new DialogInterface.OnClickListener(){
            public void onClick(DialogInterface dialog,int which){
                textSize =which;
            }
        })
                .setPositiveButton("确定", new DialogInterface.OnClickListener() {
                    @Override
                    public void onClick(DialogInterface dialog, int which) {
                        //为textview设置在单选对话框中选择的字体大小
                        textView.setTextSize(textSizeArr[textSize]);
                        dialog.dismiss();//关闭对话框
                    }
                })//添加“确定”按钮
        .setNegativeButton("取消", new DialogInterface.OnClickListener() {
            @Override
            public void onClick(DialogInterface dialog, int which) {
                dialog.dismiss();
            }
        });
        dialog=builder.create();
        dialog.show();
    }
}

3.布局(详见:Android第五周上机word文档)

<?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="#ADD8E6"
    android:layout_margin="2dp"
    tools:context=".MainActivity">
    <TextView
        android:id="@+id/v1"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:text="1.TextView显示文本信息"
        android:textSize="30sp"
        android:textColor="#9370DB"
        android:textStyle="bold"
        android:gravity="center"
        android:layout_marginTop="10dp"
        />
    <Button
        android:id="@+id/v2"
        android:layout_width="340dp"
        android:layout_height="wrap_content"
        android:text="2.按钮"
        android:textSize="20sp"
        android:textColor="#9370DB"
        android:textStyle="bold"
        android:padding="5dp"
        android:layout_centerHorizontal="true"
        android:layout_below="@+id/v1"
        />
    <EditText
        android:id="@+id/v3"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:hint="3.编辑框：请输入信息"
        android:textSize="20sp"
        android:textColorHint="#9370DB"
        android:layout_below="@id/v2"
        android:layout_alignStart="@id/v2"
        android:layout_margin="5dp"
        />
    <RadioGroup
        android:id="@+id/v4"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:orientation="horizontal"
        android:layout_below="@id/v3"
        android:layout_alignLeft="@id/v3"
        >
        <RadioButton
            android:id="@+id/v5"
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"
            android:text="4.男"
            android:textColor="#9370DB"
            android:textSize="20sp"
            android:textStyle="bold"
            />
        <RadioButton
            android:id="@+id/v6"
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"
            android:text="女"
            android:textColor="#9370DB"
            android:textSize="20sp"
            android:textStyle="bold"
            />
    </RadioGroup>
    <LinearLayout
        android:id="@+id/v7"
        android:layout_width="match_parent"
        android:layout_height="match_parent"
        android:orientation="vertical"
        android:layout_below="@id/v4"
        android:layout_alignLeft="@id/v4">
        <CheckBox
            android:id="@+id/v8"
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"
            android:text="电脑"
            android:textSize="20sp"
            />
        <CheckBox
            android:id="@+id/v9"
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"
            android:text="手机"
            android:textSize="20sp"/>
    </LinearLayout>
</RelativeLayout>

4.教材p76页 图3—17购物商城界面

<?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"
    android:orientation="vertical"
    tools:context=".MainActivity">

    <TextView
        android:layout_width="match_parent"
        android:layout_height="45dp"
        android:text="购物商城"
        android:textSize="18sp"
        android:textColor="#87CEEB"
        android:background="#FFC0CB"
        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"
    android:orientation="vertical"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:padding="16dp">

    <ImageView
        android:id="@+id/iv"
        android:layout_width="120dp"
        android:layout_height="90dp"
        android:layout_centerVertical="true"/>

    <RelativeLayout
        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:textSize="20sp"
            android:textColor="#000000"/>

        <TextView
            android:id="@+id/tv_price"
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"
            android:text="价格"
            android:textSize="20sp"
            android:layout_marginTop="10dp"
            android:layout_below="@+id/title"
            android:textColor="#DDA0DD"/>

        <TextView
            android:id="@+id/price"
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"
            android:text="1000"
            android:textSize="20sp"
            android:layout_below="@+id/title"
            android:layout_toRightOf="@+id/tv_price"
            android:textColor="#DDA0DD"
            android:layout_marginTop="10dp"/>

</RelativeLayout>
</RelativeLayout>

package com.example.cnitcastlistview;

import androidx.appcompat.app.AppCompatActivity;

import android.annotation.SuppressLint;
import android.app.Activity;
import android.os.Bundle;
import android.view.View;
import android.view.ViewGroup;
import android.widget.BaseAdapter;
import android.widget.ImageView;
import android.widget.ListView;
import android.widget.TextView;

public class MainActivity extends Activity {
    private ListView mListView;
    //商品名称与价格数据集合
    public String[] titles ={"桌子","苹果","蛋糕","毛衣"};
    private String[] prices ={"1800元","10元/kg","300元","350元"};
//图片数据集合
    private int [] icons ={R.drawable.table,R.drawable.apple,R.drawable.cake,R.drawable.wireclotes};
    @SuppressLint("WrongViewCast")
    protected  void onCreate(Bundle savedInstanceState){
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
        mListView =(ListView) findViewById(R.id.iv);//初始化ListView控件
        MyBaseAdapter mAdapter =new MyBaseAdapter();//创建一个Adapter实例
        mListView.setAdapter(mAdapter);//设置Adapter
    }
    class MyBaseAdapter extends BaseAdapter{

        @Override
        public int getCount() {//获取item的总数
            return titles.length;//返回ListView Item条目的总数
        }

        @Override
        public Object getItem(int position) {
            return titles[position];//返回Item的数据对象
        }

        @Override
        public long getItemId(int position) {
            return position;//返回Item的id
        }
//得到Item的View视图
        @Override
        public View getView(int position, View convertView, ViewGroup parent) {
            //加载List—item。xml布局文件
            View view =View.inflate(MainActivity.this,R.layout.list_item,null);
            TextView title =(TextView) view.findViewById(R.id.title);
            TextView price =(TextView) view.findViewById(R.id.price);
            ImageView iv=(ImageView) view.findViewById(R.id.iv);
            title.setText(titles[position]);
            price.setText(prices[position]);

            iv.setBackgroundResource(icons[position]);
            return view;
        }
    }

}