第四次作业

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.AlertDialog;
import androidx.appcompat.app.AppCompatActivity;
 
import android.content.DialogInterface;
import android.os.Bundle;
 
public class Main6Activity extends AppCompatActivity {
 
    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main6);
 
    }
 
    @Override
    public void onBackPressed() {
        final AlertDialog dialog;
        AlertDialog.Builder builder=new AlertDialog.Builder(this)
                .setTitle("普通对话框")//设置对话框标题
                .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
                        Main6Activity.this.finish();//关闭MainActivity
                    }
                })
                //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();
 
    }
}

　　

 

 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:context=".Main3Activity">
    <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="20sp"
        android:layout_marginTop="10dp"
        android:textColor="#FFFDB371"/>
    <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="10dp"/>
 
</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.TextView;
 
public class Main3Activity extends AppCompatActivity implements View.OnClickListener {
    private TextView textView;
    private String[] sexArry= {"男", "女"};
    int sex = 1;
 
    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main3);
        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();//关闭对话框
                        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();
    }
}

　　

 

 3.布局

<?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=".Main7Activity"
    android:background="#4CAF50">
    <TextView
        android:id="@+id/t_1"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:text="1.TixtView显示文本信息"
        android:textSize="25dp"
        android:textColor="#F81F1F"
        android:gravity="center"/>
    <Button
        android:id="@+id/bt1"
        android:layout_width="300dp"
        android:layout_height="wrap_content"
        android:text="2.按钮"
        android:textSize="25dp"
        android:textColor="#F81F1F"
        android:layout_below="@id/t_1"
        android:layout_centerHorizontal="true"/>
    <EditText
        android:id="@+id/e1"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:layout_below="@id/bt1"
        android:hint="输入信息"
        android:maxLines="2"
        android:textSize="25dp"/>
    <RadioButton
        android:id="@+id/rbtn1"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:textSize="25dp"
        android:text="男"
        android:layout_below="@id/e1"/>
    <RadioButton
        android:id="@+id/rbtn2"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:textSize="25dp"
        android:text="女"
        android:layout_toRightOf="@id/rbtn1"
        android:layout_below="@id/e1"
        android:layout_marginLeft="5dp"/>
    <CheckBox
        android:id="@+id/cb1"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:layout_below="@id/rbtn1"
        android:text="电脑"
        android:textSize="25dp"/>
    <CheckBox
        android:id="@+id/cb2"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:layout_below="@id/cb1"
        android:text="手机"
        android:textSize="25dp"/>
</RelativeLayout>

　　

 

 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"
    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=".Main8Activity">
    <TextView
        android:layout_width="match_parent"
        android:layout_height="45dp"
        android:text="购物商城"
        android:textSize="18sp"
        android:background="#FF8F03"
        android:gravity="center"/>
    <ListView
        android:id="@+id/lv"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"/>
 
</LinearLayout>

　　

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.ListAdapter;
import android.widget.ListView;
import android.widget.TextView;
 
public class Main8Activity 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.dangao, R.drawable.maoyi, R.drawable.mihoutao, R.drawable.weijin};
 
    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main8);
        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(Main8Activity.this, R.layout.list_item, null);
            TextView title = view.findViewById(R.id.title1);
            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;
        }
    }
 
}