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 android.os.Bundle;
import android.app.Activity;
import android.app.AlertDialog;
import android.app.AlertDialog.Builder;
import android.content.DialogInterface;
import android.text.AlteredCharSequence;
import android.view.Menu;

public class MainActivity extends Activity {

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

    }
    @Override
    public void onBackPressed() {
        // TODO Auto-generated method stub
        AlertDialog.Builder builder=new AlertDialog.Builder(this)
                .setTitle("普通对话框")
                .setMessage("是否退出至主菜单")
                .setIcon(R.drawable.ic_launcher_background)
                .setPositiveButton("确定", new DialogInterface.OnClickListener() {

                    @Override
                    public void onClick(DialogInterface dialog, int which) {
                        // TODO Auto-generated method stub
                        dialog.dismiss();
                        MainActivity.this.finish();
                    }
                })
                .setNegativeButton("取消", new DialogInterface.OnClickListener() {

                    @Override
                    public void onClick(DialogInterface dialog, int which) {
                        // TODO Auto-generated method stub
                        dialog.dismiss();
                    }
                });
        AlertDialog 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;

public class Main3Activity extends AppCompatActivity implements View.OnClickListener {
    private  TextView textView;
    private String[] textSizeArr={"男","女"};
    int textSize =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){
        final AlertDialog dialog;
        AlertDialog.Builder builder =new AlertDialog.Builder(this)
                .setTitle("选择性别")
                .setIcon(R.mipmap.ic_launcher)
                .setSingleChoiceItems(new String[]{"男", "女"}, textSize, new DialogInterface.OnClickListener() {
                    public void onClick(DialogInterface dialogInterface, int i) {
                        textSize=i;
                    }
                })
                .setPositiveButton("确定",new DialogInterface.OnClickListener(){
                    @Override
                    public void  onClick(DialogInterface dialog,int i){
                        if (i==1){
                            textView.setText("您的性别是：男");
                        }else {
                            textView.setText("您的性别是：女");
                        }
                        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)

 

 

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"
    tools:context=".MainActivity"
    android:orientation="vertical">
    <TextView
        android:id="@+id/tv"
        android:layout_width="match_parent"
        android:layout_height="50dp"
        android:text="购物商城"
        android:textColor="#E8E3E9"
        android:background="#C175CE"
        android:textSize="20sp"
        android:gravity="center"/>
    <ListView
        android:id="@+id/lv"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"/>

</LinearLayout>

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 ListView mListView;
    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"};
    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 myAdapter = new MyBaseAdapter();
        mListView.setAdapter(myAdapter);
    }
    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 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 view1;
        }
    }
}