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 cn.itcase.commondialog;

import android.os.Bundle;import android.app.AlertDialog;
import android.content.DialogInterface;
import androidx.appcompat.app.AppCompatActivity;

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")
                .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) {
                        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"
    tools:context=".MainActivity"
    android:orientation="vertical">

    <Button
        android:id="@+id/btn"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:text="请选择你的性别"
        android:textSize="30dp"
        android:layout_marginTop="30dp"
        android:layout_gravity="center"/>

</LinearLayout>

package com.example.radiobutton;

import android.os.Bundle;
import android.app.Activity;
import android.app.AlertDialog;
import android.content.DialogInterface;
import android.view.View;
import android.view.View.OnClickListener;
import android.widget.Toast;

public class MainActivity extends Activity implements OnClickListener {

    private int num0=0;
    private int num1[]={0,1};
    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
        findViewById(R.id.btn).setOnClickListener(this);
    }
    @Override
    public void onClick(View v) {
        // TODO Auto-generated method stub
        AlertDialog.Builder builder=new AlertDialog.Builder(this)
                .setTitle("性别")
                .setSingleChoiceItems(new String[]{"男","女"}, -1, new DialogInterface.OnClickListener() {
                    @Override
                    public void onClick(DialogInterface dialog, int which) {
                        // TODO Auto-generated method stub
                        num0=which;
                    }
                })
                .setPositiveButton("确定",new DialogInterface.OnClickListener() {
                    @Override
                    public void onClick(DialogInterface dialog, int which) {
                        // TODO Auto-generated method stub
                        if(num0==0){
                            Toast.makeText(MainActivity.this, "您选择的是男", Toast.LENGTH_LONG).show();
                        }else{
                            Toast.makeText(MainActivity.this, "您选择的是女", Toast.LENGTH_SHORT).show();
                        }
                        dialog.dismiss();
                    }
                })
                .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();
    }
}

 

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="#00FF05"
    android:orientation="vertical">

    <TextView
        android:id="@+id/tv_1"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:layout_marginTop="15dp"
        android:gravity="center"
        android:text="1TextView显示文本信息"
        android:textColor="#FF0F00"
        android:textSize="25sp"
        android:textStyle="italic" />

    <Button
        android:id="@+id/btn_1"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:layout_marginLeft="15dp"
        android:layout_marginRight="15dp"
        android:text="2.按钮"
        android:textColor="#FF0F00"
        android:textSize="25sp" />

    <EditText
        android:id="@+id/et_1"
        android:layout_width="380dp"
        android:layout_height="wrap_content"
        android:layout_marginLeft="15dp"
        android:layout_marginRight="15dp"
        android:hint="3.编辑框:请输入信息"
        android:textColorHint="#FF0F00"
        android:textSize="25sp" />

    <LinearLayout
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:orientation="horizontal" >
        <RadioGroup
            android:layout_width="match_parent"
            android:layout_height="wrap_content"
            android:orientation="horizontal">
            <RadioButton
                android:id="@+id/rb_1"
                android:layout_width="match_parent"
                android:layout_height="wrap_content"
                android:layout_marginLeft="15dp"
                android:text="男"
                android:textColor="#FF0F00"
                android:textSize="25sp" />
            <RadioButton
                android:id="@+id/rb_2"
                android:layout_width="match_parent"
                android:layout_height="wrap_content"
                android:layout_marginLeft="15dp"
                android:text="女"
                android:textColor="#FF0F00"
                android:textSize="25sp" />
        </RadioGroup>
    </LinearLayout>
    <CheckBox
        android:id="@+id/cb_1"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:layout_marginLeft="15dp"
        android:text="电脑"
        android:textColor="#FF0F00"
        android:textSize="25sp"/>

    <CheckBox
        android:id="@+id/cb_2"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:layout_marginLeft="15dp"
        android:text="手机"
        android:textColor="#FF0F00"
        android:textSize="25sp"/>
</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"
    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;
        }
    }
}