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.chap03;

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("普通对话框")
                .setIcon(R.mipmap.ic_launcher)
                .setMessage("是否确定退出应用：")
                .setPositiveButton("确定", 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.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"
    tools:context=".MainActivity"
    android:background="#25FA2A"
    android:layout_margin="5dp">
 
    <TextView
        android:id="@+id/tv_1"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:text="1.TextView显示文本信息"
        android:textColor="#F81606"
        android:textSize="20dp"
        android:textStyle="italic"
        android:gravity="center"
        android:layout_marginTop="20dp"/>
    <Button
        android:id="@+id/bu_1"
        android:layout_width="360dp"
        android:layout_height="wrap_content"
        android:text="2.按钮"
        android:textColor="#F81606"
        android:textSize="20dp"
        android:textStyle="bold"
        android:layout_centerHorizontal="true"
        android:layout_below="@id/tv_1"
        android:padding="10dp"/>
    <EditText
        android:id="@+id/et_1"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:hint="3.编辑框：请输入信息"
        android:textColorHint="#F81606"
        android:textSize="25dp"
        android:layout_below="@id/bu_1"
        android:layout_margin="5dp"
        android:padding="10dp"/>
    <RadioGroup
        android:id="@+id/rg_1"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:layout_below="@id/et_1"
        android:layout_alignLeft="@id/et_1"
        android:orientation="horizontal"
        android:padding="5dp">
 
        <RadioButton
            android:id="@+id/rb_1"
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"
            android:text="4.男"
            android:textSize="20dp"
            android:textColor="#F81606" />
        <RadioButton
            android:id="@+id/rb_2"
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"
            android:text="女"
            android:textSize="20dp"
            android:textColor="#F81606" />
    </RadioGroup>
    <LinearLayout
        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/ck_1"
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"
            android:text="电脑"
            android:textSize="20dp"
            android:textColor="#F81606"
            android:padding="5dp" />
        <CheckBox
            android:id="@+id/ck_2"
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"
            android:text="手机"
            android:textSize="20dp"
            android:textColor="#F81606"
            android:padding="5dp"/>
    </LinearLayout>
 
</RelativeLayout>

 

 

 4.教材p76页 图3—17购物商城界面

<?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="15dp">

    <ImageView
        android:id="@+id/iv"
        android:layout_width="100dp"
        android:layout_height="80dp"
        android:layout_centerVertical="true"/>
    <RelativeLayout
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:layout_centerVertical="true"
        android:layout_marginLeft="10dp"
        android:layout_toRightOf="@id/iv">
        <TextView
            android:id="@+id/title"
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"
            android:text="桌子"
            android:textSize="20sp"
            android:textColor="#4B4343"/>
        <TextView
            android:id="@+id/tv_p"
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"
            android:text="价格"
            android:textSize="20sp"
            android:textColor="#F5A631"
            android:layout_below="@id/title"
            android:layout_marginTop="10dp"/>
        <TextView
            android:id="@+id/price"
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"
            android:text="1800"
            android:textSize="20sp"
            android:textColor="#F5A631"
            android:layout_below="@id/title"
            android:layout_toRightOf="@id/tv_p"
            android:layout_marginTop="10dp"/>

    </RelativeLayout>
</RelativeLayout>

package com.example.myapplication;

import androidx.appcompat.app.AppCompatActivity;

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 AppCompatActivity {
    private ListView mListView;
    //商品名称与价格数据集合
    private String [] titles={"桌子","苹果","蛋糕","线衣","猕猴桃","围巾"};
    private String [] prices={"1800元","10元/kg","300元","350元","10元/kg","280元"};
    //图片数据集合
    private int [] icons={R.drawable.table,R.drawable.apple,R.drawable.cake,R.drawable.wireclothes,R.drawable.kiwifruit,R.drawable.scarf};
    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
        mListView = (ListView) findViewById(R.id.lv);//初始化ListView控件
        MyBaseAdapter myAdapter = new MyBaseAdapter();//创建一个Adapter实例
        mListView.setAdapter(myAdapter);//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 i) {
            return titles[i];  //返回Item的数据对象
        }
        @Override
        public long getItemId(int i) {
            return i;   //返回Item的id
        }
        //得到Item的View视图
        @Override
        public View getView(int i, View view, ViewGroup viewGroup) {
            View view1= View.inflate(MainActivity.this,R.layout.list_item,null);
            TextView title = (TextView)view1.findViewById(R.id.title);
            TextView price = (TextView)view1.findViewById(R.id.price);
            ImageView iv = (ImageView)view1.findViewById(R.id.iv);
            title.setText(titles[i]);
            price.setText(prices[i]);
            iv.setBackgroundResource(icons[i]);
            return view1;
        }
    }
}

<?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="购物商城"
        android:textColor="#E8E3E9"
        android:background="#FF5722"
        android:textSize="20sp"
        android:gravity="center"/>
    <ListView
        android:id="@+id/lv"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"/>

</LinearLayout>