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.helloandroid;

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）

package com.example.helloandroid;

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

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

import java.util.Locale;

public class MainActivity extends AppCompatActivity implements View.OnClickListener{
    private TextView textView;
    final String [] sexs=new String[]{"男","女"};
    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
        findViewById(R.id.bt_1).setOnClickListener(this);
        textView=(TextView) findViewById(R.id.tv_1);

    }
    public void onClick(View view){
        AlertDialog dialog;
        AlertDialog.Builder builder=new AlertDialog.Builder(this);
        builder.setTitle("请选择你的性别：");
        builder.setIcon(R.mipmap.ic_launcher);
        builder.setSingleChoiceItems(sexs, 1, new DialogInterface.OnClickListener() {
            @Override
            public void onClick(DialogInterface dialog, int which) {
                Toast.makeText(MainActivity.this,"您选择的是："+sexs[which],Toast.LENGTH_LONG).show();
                dialog.dismiss();
            }
        });
        builder.setPositiveButton("确定", new DialogInterface.OnClickListener() {
            @Override
            public void onClick(DialogInterface dialog, int which) {
                Toast.makeText(MainActivity.this,"您选择了"+sexs[which],Toast.LENGTH_LONG).show();
                dialog.dismiss();
            }
        })
                .setNegativeButton("取消", new DialogInterface.OnClickListener() {
                    @Override
                    public void onClick(DialogInterface dialog, int which) {
                        dialog.dismiss();
                    }
                });
        dialog=builder.create();
        dialog.show();
    }
}

　　

<?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_1"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:text="单选对话框"
        android:gravity="center"
        android:layout_marginTop="20dp"
        android:textSize="20sp"
        android:textColor="#474141"
        android:textStyle="bold"/>
    <Button
        android:id="@+id/bt_1"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:text="请选择你的性别"
        android:layout_marginTop="20dp"
        android:layout_gravity="center"
        android:textSize="20sp"
        android:textStyle="bold"
        android:textColor="#474141"/>
</LinearLayout>

　　

 

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"
    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="#85FF01"
    android:orientation="vertical">

    <TextView
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:layout_marginTop="60dp"
        android:text="1.TextView显示的文本信息"
        android:textSize="25dp"
        android:layout_marginLeft="50dp"
        android:textColor="#FF0000"
        />

    <Button
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:layout_marginLeft="50dp"
        android:layout_marginTop="61dp"
        android:layout_marginRight="50dp"
        android:textSize="25dp"
        android:text="2.按钮"
        android:textColor="#FF0000" />
    <EditText
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:text="3.编辑框:请输入信息"
        android:textSize="25dp"
        android:textColor="#FF0000"
        android:layout_marginLeft="25dp"
        android:layout_marginTop="62dp"/>
    <RadioGroup
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:layout_marginLeft="15dp"
        android:orientation="horizontal">
        <RadioButton
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"
            android:text="4.男"
            android:checked="true"
            android:textColor="#FF0000"
            android:textSize="25dp"></RadioButton>
        <RadioButton
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"
            android:text="女"
            android:textColor="#FF0000"
            android:textSize="25dp"></RadioButton>

    </RadioGroup>
    <CheckBox
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:text="电脑"
        android:textSize="25dp"
        android:textColor="#FF0000"
        android:checked="true"
        android:layout_marginLeft="20dp"
        />
    <CheckBox
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:text="手机"
        android:textSize="25dp"
        android:textColor="#FF0000"
        android:checked="true"
        android:layout_marginLeft="20dp"
        />

</LinearLayout>

　　

 

 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"
    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="购物商城"
        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>

　　

package com.example.helloandroid;
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.ListAdapter;
import android.widget.ListView;
import android.widget.TextView;

public class MainActivity extends AppCompatActivity {
    private ListView mListView;
    private String[] titles = {"桌子", "苹果", "蛋糕", "线衣", "猕猴桃", "围巾"};
    private String[] prices = {"1800元", "10/kg", "300元", "350元", "10/kg", "280元"};
    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);
        MyBaseAdapter mAdapter = new MyBaseAdapter();
        mListView.setAdapter( mAdapter);
    }
    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 = View.inflate(MainActivity.this, R.layout.chenxi, null);
            TextView title = view.findViewById(R.id.name_shop);
            TextView price = view.findViewById(R.id.price_shop);
            ImageView iv = view.findViewById(R.id.shop_iv);
            title.setText(titles[i]);
            price.setText(prices[i]);
            iv.setImageResource(icons[i]);
            return view;
        }
    }

}