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.myapplication;
import androidx.appcompat.app.AppCompatActivity;
import android.app.AlertDialog;
import android.content.DialogInterface;
import android.os.Bundle;
public class a1 extends AppCompatActivity {

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.a1);
    }

    @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();
                        a1.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.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.TextView;
import android.widget.Toast;

public class a2 extends AppCompatActivity implements View.OnClickListener {
    private TextView textView;
    private String[] sex1= {"男", "女"};
    int sex = 1;

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.a2);
        findViewById(R.id.bt).setOnClickListener(this);
        textView = (TextView) findViewById(R.id.tv);
    }

    @Override
    public void onClick(View v) {
        AlertDialog dialog;
        AlertDialog.Builder builder=new AlertDialog.Builder(this)
                .setTitle("选择性别")
                .setIcon(R.mipmap.ic_launcher)
                .setSingleChoiceItems(new String[]{"男", "女"}, sex, new DialogInterface.OnClickListener() {
                    @Override
                    public void onClick(DialogInterface dialog, int i) {
                        sex=i;
                    }
                })
                .setPositiveButton("确定", new DialogInterface.OnClickListener() {
                    @Override
                    public void onClick(DialogInterface dialog, int i) {
                        dialog.dismiss();
                        if (sex==1){
                            textView.setText("您的性别是：女");
                        }else{
                            textView.setText("您的性别是：男");
                        }
                    }
                })
                //t添加"取消"按钮
                .setNegativeButton("取消", new DialogInterface.OnClickListener() {
                    @Override
                    public void onClick(DialogInterface dialog, int i) {
                        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"
    android:orientation="vertical"
    tools:context=".MainActivity">
    <TextView
        android:id="@+id/tv"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:text="您的性别是："
        android:gravity="center"
        android:textSize="25sp"
        android:layout_marginTop="20dp"
        android:textColor="#000000"/>
    <Button
        android:id="@+id/bt"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:text="选择性别"
        android:layout_gravity="center"
        android:layout_marginTop="30dp"/>

</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

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.view.ViewGroup;
import android.widget.BaseAdapter;
import android.widget.ImageView;
import android.widget.ListView;
import android.widget.TextView;
import android.widget.Toast;

////implements View.OnClickListener
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.text64);
        mListView = (ListView) findViewById(R.id.lv_1);
        //MyBaseAdapter mAdapter = new MyBaseAdapter();
        mListView.setAdapter(new MyBaseAdapter());
    }
     class MyBaseAdapter extends BaseAdapter {

        @Override
        public int getCount() {
            return titles.length;
        }

        @Override
        public Object getItem(int position) {
            return titles[position];
        }

        @Override
        public long getItemId(int position) {
            return position;
        }

        @Override
        public View getView(int position, View convertView, ViewGroup parent) {
           View view = View.inflate(MainActivity.this, R.layout.text64_item, null);
            TextView title = view.findViewById(R.id.tv_list);
            TextView price = view.findViewById(R.id.tv_price);
            ImageView iv = view.findViewById(R.id.image);
            title.setText(titles[position]);
            price.setText(prices[position]);
            iv.setImageResource(icons[position]);
            return view;
        }
    }
    @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("是否退出应用:")
                .setPositiveButton("确定", new DialogInterface.OnClickListener() {
                    @Override
                    public void onClick(DialogInterface dialog, int i) {
                        dialog.dismiss();
                        MainActivity.this.finish();
                    }
                })
                .setNegativeButton("取消", new DialogInterface.OnClickListener() {
                    @Override
                    public void onClick(DialogInterface dialog, int i) {
                        dialog.dismiss();
                    }
                });

        dialog=builder.create();
        dialog.show();
   }
}