第三次作业 9.18
1、返回键实现对话框弹出是否退出应用程序
package itcast.cn; import android.app.AlertDialog; import android.content.DialogInterface; import android.os.Bundle; import android.app.Activity; public class Main2Activity extends Activity { protected void onCreate(Bundle savedInstanceState) { super.onCreate(savedInstanceState); setContentView(R.layout.activity_main2); } public void onBackPressed(){ AlertDialog dialog; AlertDialog.Builder builder=new AlertDialog.Builder(this) .setTitle("普通对话框") .setIcon(R.drawable.ic_launcher_background) .setMessage("是否确定退出") .setPositiveButton("确定", new DialogInterface.OnClickListener() { public void onClick(DialogInterface dialog, int which) { dialog.dismiss(); Main2Activity.this.finish();} }) .setNegativeButton("取消", new DialogInterface.OnClickListener() { 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 android.os.Bundle; import android.app.Activity; import android.app.AlertDialog; import android.app.AlertDialog.Builder; import android.content.DialogInterface; import android.view.Menu; import android.view.View; import android.view.View.OnClickListener; import android.widget.Button; import android.widget.Toast; public class MainActivity extends Activity implements OnClickListener { private int num=0; private int num1[]={0,1}; @Override protected void onCreate(Bundle savedInstanceState) { super.onCreate(savedInstanceState); setContentView(R.layout.activity_main); findViewById(R.id.bt).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 num=which; } }) .setPositiveButton("确定",new DialogInterface.OnClickListener() { @Override public void onClick(DialogInterface dialog, int which) { // TODO Auto-generated method stub if(num==0){ Toast.makeText(MainActivity.this, "你选择的是男", Toast.LENGTH_LONG).show(); }else{ Toast.makeText(MainActivity.this, "你选择的是女", 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(); } } 复制代码 复制代码 <?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"> <Button android:id="@+id/bt" android:layout_width="wrap_content" android:layout_height="wrap_content" android:text="请选择你的性别" /> </RelativeLayout>
3.布局(详见:Android第五周上机word文档)
<?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" android:background="#31B404" android:layout_margin="2dp" tools:context=".MyLayout"> <TextView android:id="@+id/tv_1" android:layout_width="match_parent" android:layout_height="wrap_content" android:text="1.TextView显示文本信息" android:textSize="20sp" android:textColor="#FF0000" android:textStyle="bold" android:gravity="center" android:layout_marginTop="10dp" /> <Button android:id="@+id/btn_1" android:layout_width="350dp" android:layout_height="wrap_content" android:text="2.按钮" android:textSize="20sp" android:textColor="#FF0000" android:textStyle="bold" android:padding="5dp" android:layout_centerHorizontal="true" android:layout_below="@+id/tv_1" /> <EditText android:id="@+id/et_1" android:layout_width="match_parent" android:layout_height="wrap_content" android:hint="3.编辑框：请输入信息" android:textSize="20sp" android:textColorHint="#FF0000" android:layout_below="@id/btn_1" android:layout_alignStart="@id/btn_1" android:layout_margin="5dp" /> <RadioGroup android:id="@+id/rg_1" android:layout_width="wrap_content" android:layout_height="wrap_content" android:orientation="horizontal" android:layout_below="@id/et_1" android:layout_alignLeft="@id/et_1" > <RadioButton android:id="@+id/rb_1" android:layout_width="wrap_content" android:layout_height="wrap_content" android:text="4.男" android:textColor="#FF0000" android:textSize="20sp" android:textStyle="bold" /> <RadioButton android:id="@+id/rb_2" android:layout_width="wrap_content" android:layout_height="wrap_content" android:text="女" android:textColor="#FF0000" android:textSize="20sp" android:textStyle="bold" /> </RadioGroup> <LinearLayout android:id="@+id/ll_1" android:layout_width="match_parent" android:layout_height="match_parent" android:orientation="vertical" android:layout_below="@id/rg_1" android:layout_alignLeft="@id/rg_1"> <CheckBox android:id="@+id/cb_1" android:layout_width="wrap_content" android:layout_height="wrap_content" android:text="电脑" android:textSize="20sp" /> <CheckBox android:id="@+id/cb_2" android:layout_width="wrap_content" android:layout_height="wrap_content" android:text="手机" android:textSize="20sp"/> </LinearLayout> </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" tools:context=".MainActivity" android:orientation="vertical"> <TextView android:layout_width="match_parent" android:layout_height="45dp" android:text="购物商城" android:background="#53FF53" android:textSize="18sp" android:textColor="#FFFF37" android:gravity="center"/> <ListView android:layout_width="match_parent" android:layout_height="wrap_content" android:id="@+id/lv" /> </LinearLayout>
<?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" android:padding="16dp"> <ImageView android:layout_width="120dp" android:layout_height="90dp" android:id="@+id/iv" android:layout_centerVertical="true"/> <RelativeLayout android:layout_width="wrap_content" android:layout_height="wrap_content" android:layout_marginLeft="10dp" android:layout_toRightOf="@+id/iv" android:layout_centerVertical="true"> <TextView android:layout_width="wrap_content" android:layout_height="wrap_content" android:id="@+id/title" android:text="桌子" android:textSize="20sp" android:textColor="#FFFF37" /> <TextView android:layout_width="wrap_content" android:layout_height="wrap_content" android:id="@+id/tv_price" android:text="价格" android:layout_below="@id/title" android:layout_marginTop="10dp" android:textSize="20sp" android:textColor="#FFFF37" /> <TextView android:layout_width="wrap_content" android:layout_height="wrap_content" android:id="@+id/price" android:text="1000" android:textSize="20sp" android:layout_below="@id/title" android:layout_toRightOf="@id/tv_price" android:layout_marginTop="10dp" android:textColor="#FFFF37" /> </RelativeLayout> </RelativeLayout>
package com.example.myapplication; import androidx.appcompat.widget.ViewUtils; import android.app.Activity; 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 Activity { private ListView mListView; //商品名称与价格数据集合 private String[ ] titles = {"桌子","苹果","蛋糕","线衣","猕猴桃","围巾"}; private String[ ] prices = {"1000元","10元/kg","300元","350元","10元/kg","280元"}; //图片数据集合 private int[ ] icons = {R.drawable.table,R.drawable.apple,R.drawable.cake,R.drawable. wireclothes,R.drawable.kiwifruit,R.drawable.scarf}; protected void onCreate(Bundle savedInstanceState) { super.onCreate(savedInstanceState); setContentView(R.layout.activity_main); mListView = (ListView)findViewById(R.id.lv); //初始化ListView 控件 MyBaseAdapter mAdapter = new MyBaseAdapter();//创建一个Adapter实例 mListView.setAdapter(mAdapter); //设置Adapter } class MyBaseAdapter extends BaseAdapter{ @Override public int getCount(){ //获取item的总数 return titles.length; //返回ListView Item条目的总数 } @Override public Object getItem(int position){ return titles[position]; //返回Item的数据对象 } @Override public long getItemId(int position){ return position; //返回Item的id } //得到Item的View视图 @Override public View getView(int position,View convertView,ViewGroup parent){ //加载list_item.xml布局文件 View view = View.inflate(MainActivity.this,R.layout.list_item,null); TextView title = (TextView) view.findViewById(R.id.title); TextView price = (TextView) view.findViewById(R.id.price); ImageView iv = (ImageView) view.findViewById(R.id.iv); title.setText(titles[position]); price.setText(prices[position]); iv.setBackgroundResource(icons[position]); return view; } } }
