安卓第五，六周作业

1.返回键实现对话框弹出是否退出应用程序

package com.example.myapplication55;

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

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

public class MainActivity extends AppCompatActivity {

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



    public boolean onKeyDown(int keyCode, KeyEvent event) {
        //点击返回键
        if(keyCode==KeyEvent.KEYCODE_BACK){
            //声明弹出对象并初始化
            AlertDialog.Builder builder=new AlertDialog.Builder(this);
            builder.setTitle("提示：");
            builder.setMessage("是否退出?");
            //设置确定按钮
            builder.setNegativeButton("确定", new DialogInterface.OnClickListener() {
                @Override
                public void onClick(DialogInterface dialog, int which) {
                    finish();
                }
            });
            //设置取消按钮
            builder.setPositiveButton("取消",null);
            //显示弹窗
            builder.show();
        }
        return super.onKeyDown(keyCode,event);
    }
}

 

 

 

 

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"

    android:layout_width="match_parent"
    android:layout_height="match_parent">
<Button
    android:id="@+id/bt"
    android:layout_width="wrap_content"
    android:layout_height="wrap_content"
    android:text="按钮"/>
    </LinearLayout>
/////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////

package com.example.myapplication55;
import android.app.AlertDialog;
import androidx.appcompat.app.AppCompatActivity;

import android.content.DialogInterface;
import android.os.Bundle;
import android.view.View;
import android.widget.Toast;
public class MainActivity extends AppCompatActivity implements View.OnClickListener {
    int x = 0;
    private String Arr[] = {"你选择了男","你选择了女"};
    @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){
        AlertDialog dialog;
        AlertDialog.Builder builder = new AlertDialog.Builder(this);
        builder.setTitle("性别");
        builder.setSingleChoiceItems(new String[]{"男", "女"},0,new DialogInterface.OnClickListener() {
            @Override
            public void onClick(DialogInterface dialog, int which) {
                x = which;
//                Toast.makeText(MainActivity.this,Arr[i], Toast.LENGTH_SHORT).show();
            }
        });
        builder.setPositiveButton("确定", new DialogInterface.OnClickListener() {

            @Override
            public void onClick(DialogInterface dialog, int which) {
//                final String items[]={"男","女"};
                Toast.makeText(MainActivity.this,Arr[x], Toast.LENGTH_SHORT).show();
                dialog.dismiss();
            }
        });
        builder.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:tools="http://schemas.android.com/tools"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    tools:context=".MainActivity"
    android:background="#0DBAFF">

    <TextView
        android:layout_width="match_parent"
        android:layout_height="40dp"
        android:text="1.TextView显示的文本信息"
        android:textSize="30sp"
        android:layout_marginLeft="40dp"
        android:layout_marginRight="60dp"
        android:layout_marginTop="40dp"
        android:textColor="#4CFF00"
        />
    <Button
        android:layout_width="match_parent"
        android:layout_height="60dp"
        android:text="2.按钮"
        android:textSize="30sp"
        android:layout_marginLeft="20dp"
        android:layout_marginRight="20dp"
        android:layout_marginTop="90dp"
        android:textColor="#4CFF00"/>
    <EditText
        android:layout_width="match_parent"
        android:layout_height="60dp"

        android:text="3.编辑框：请输入信息"
        android:textSize="30sp"
        android:layout_marginLeft="20dp"
        android:layout_marginRight="20dp"
        android:layout_marginTop="150dp"
        android:textColor="#4CFF00"/>

    <RadioGroup
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:layout_marginLeft="20dp"
        android:layout_marginRight="20dp"
        android:orientation="horizontal">

        <RadioButton
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"
            android:layout_marginTop="250dp"
            android:text="4.男"
            android:textColor="#4CFF00"
            android:textSize="30sp" />

        <RadioButton
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"
            android:layout_marginTop="250dp"
            android:text="女"
            android:textColor="#4CFF00"
            android:textSize="30sp" />

    </RadioGroup>
    <CheckBox
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:text="电脑"
        android:textColor="#4CFF00"
        android:textSize="30sp"
        android:layout_marginLeft="20dp"
        android:layout_marginRight="20dp"
        android:layout_marginTop="300dp"/>
    <CheckBox
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:text="手机"
        android:textColor="#4CFF00"
        android:textSize="30sp"
        android:layout_marginLeft="20dp"
        android:layout_marginRight="20dp"
        android:layout_marginTop="340dp"/>

</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="#03A9F4"
            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="#2196F3"
            android:layout_below="@id/title"
            android:layout_toRightOf="@id/tv_p"
            android:layout_marginTop="10dp"/>

    </RelativeLayout>
</RelativeLayout>

<?xml version="1.0" encoding="utf-8"?>
<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"

    xmlns:tools="http://schemas.android.com/tools"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    tools:context=".MainActivity">

    <TextView
        android:id="@+id/gw"
        android:layout_width="match_parent"
        android:layout_height="40dp"
        android:text="购物商城"
        android:background="#2196F3"
        android:textSize="25sp"
        android:gravity="center"/>
    <ListView
        android:id="@+id/lv"
        android:layout_width="match_parent"
        android:layout_height="match_parent"
        android:layout_below="@id/gw"/>


</RelativeLayout>

package cn.itcast.listview;

import androidx.appcompat.app.AppCompatActivity;

import android.os.Bundle;
import android.view.View;
import android.view.ViewGroup;
import android.widget.ImageView;
import android.widget.ListView;
import android.widget.BaseAdapter;
import android.widget.TextView;

public class MainActivity extends AppCompatActivity {
    private ListView mListView;

    private String [] titles={"桌子","苹果","蛋糕","线衣"};
    private String [] prices={"1800元","10元/kg","300元","350元"};

    private int [] icons={R.drawable.table,R.drawable.apple,R.drawable.cake,R.drawable.wireclothes};
    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
        mListView = (ListView) findViewById(R.id.lv);
        MyBaseAdapter myAdapter = new MyBaseAdapter();
        mListView.setAdapter(myAdapter);
    }
    class MyBaseAdapter extends BaseAdapter{
        @Override
        public int getCount() {
            return titles.length;
        }
        @Override
        public Object getItem(int i) {
            return titles[i];
        }
        @Override
        public long getItemId(int i) {
            return i;
        }

        @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 view;
        }
    }
}