Android第5、6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.textapplication;

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

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


public class MainActivity<cli> extends AppCompatActivity {

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main); //启动界面

    }

    @Override
    public void onBackPressed() {
        final AlertDialog dialog;
        AlertDialog.Builder builder = new AlertDialog.Builder(this)
                .setTitle("普通对话框")     //对话框标题
                .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 i) {
                        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 i) {
                dialog.dismiss();   //关闭对话框
            }
        });
        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"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:orientation="vertical">
    <TextView
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:text="单选对话框"
        android:textSize="50sp"
        android:textAlignment="center"
        android:layout_marginTop="20dp"/>
    <Button
        android:id="@+id/btn"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:text="性别选择"
        android:textSize="30sp"
        android:layout_gravity="center"/>

</LinearLayout>

package com.example.myapplication;

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

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

public class MainActivity extends AppCompatActivity implements View.OnClickListener {
    private Button btn;
    private String[] sexarr = {"男", "女"};
    int sex;

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
        btn = findViewById(R.id.btn);
        btn.setOnClickListener(this);
    }

    @Override
    public void onClick(View view) {
        if (view.getId() == R.id.btn) {
            final AlertDialog dialog; // 声明对象
            AlertDialog.Builder builder = new AlertDialog.Builder(this)
                    .setTitle("选择性别")   // 标题
                    .setIcon(R.mipmap.ic_launcher)  // 图标
                    .setSingleChoiceItems(new String[]{"男", "女"}, sex, new DialogInterface.OnClickListener() {
                        @Override
                        public void onClick(DialogInterface dialogInterface, int i) {
                            sex = i;
                        }
                    })
                    .setPositiveButton("确定", new DialogInterface.OnClickListener() {
                        @Override
                        public void onClick(DialogInterface dialog, int i) {
                            Toast.makeText(MainActivity.this, "您的性别是"+sexarr[sex], Toast.LENGTH_LONG).show();
                            dialog.dismiss();
                        }
                    })
                    .setNegativeButton("取消", new DialogInterface.OnClickListener() {
                        @Override
                        public void onClick(DialogInterface dialog, int i) {
                            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"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:background="#00FF00"
    android:orientation="vertical"
    android:layout_margin="20dp">

    <TextView
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:layout_margin="30dp"
        android:text="1.TextView显示文本信息"
        android:textAlignment="center"
        android:textColor="#FF0000"
        android:textSize="25sp"
        android:textStyle="italic" />

    <Button
        android:id="@+id/btn"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:layout_gravity="center"
        android:layout_marginHorizontal="20dp"
        android:layout_marginTop="10dp"
        android:text="2.按钮"
        android:textColor="#FF0000"
        android:textSize="30sp" />

    <EditText
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:layout_marginHorizontal="20dp"
        android:text="3.编辑框：请输入信息"
        android:textColor="#FF0000"
        android:textSize="20sp" />

    <RadioGroup
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:orientation="horizontal">

        <RadioButton
            android:layout_width="match_parent"
            android:layout_height="wrap_content"
            android:layout_marginLeft="20dp"
            android:text="4.男"
            android:textColor="#FF0000"
            android:textSize="20sp" />

        <RadioButton
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"
            android:text="女"
            android:layout_marginLeft="20dp"
            android:textColor="#FF0000"
            android:textSize="20sp" />
    </RadioGroup>
    <CheckBox
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:layout_marginLeft="20dp"
        android:text="电脑"
        android:textColor="#FF0000"
        android:textSize="20sp" />
    <CheckBox
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:layout_marginLeft="20dp"
        android:text="手机"
        android:textColor="#FF0000"
        android:textSize="20sp"/>


</LinearLayout>

 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"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:orientation="vertical">
    <TextView
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:background="#FFBF00"
        android:text="购物商城"
        android:textColor="#FFFFFF"
        android:textSize="30sp"
        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: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_below="@id/title"
            android:layout_marginTop="10dp"
            android:textColor="#000000"/>
        <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="#FF8F03"
            android:layout_marginTop="10dp"/>
    </RelativeLayout>
</RelativeLayout>

package com.example.listview;

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 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);
        ListView listView = findViewById(R.id.lv);
        MyBaseAdapter adapter = new MyBaseAdapter();
        listView.setAdapter(adapter);
    }

    class MyBaseAdapter extends BaseAdapter{

        @Override
        public int getCount() {     //获取item总数
            return titles.length;
        }

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

        @Override
        public long getItemId(int i) {      //返回item的id
            return i;
        }

        @Override
        public View getView(int i, View View, ViewGroup viewGroup) {    //获取item中的viwe视图
            //将list_item.xml文件转换为viwe对象
            View view = View.inflate(MainActivity.this,R.layout.list_item,null );

            //初始化view对象(list_item.xml)中的控件
            TextView title = view.findViewById(R.id.title);
            TextView price = view.findViewById(R.id.price);
            ImageView iv = view.findViewById(R.id.iv);

            title.setText(titles[i]);
            price.setText(prices[i]);
            iv.setImageResource(icons[i]);
            return view;
        }
    }
}