ListView控件---商品展示案例

最新推荐文章于 2022-09-27 11:04:21 发布

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最新推荐文章于 2022-09-27 11:04:21 发布

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本文链接：https://blog.youkuaiyun.com/pang_12150/article/details/70313439

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本文介绍了一个使用Android ListView实现的商品展示案例，包括界面布局、数据库操作、数据模型定义及界面交互等核心部分。通过此案例，读者可以了解到如何创建一个简单的商品列表应用。

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ListView控件---商品展示案例

1.创建程序

<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:tools="http://schemas.android.com/tools"
    android:id="@+id/activity_main"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:orientation="vertical"
    tools:context="com.example.bz0209.myapplication.MainActivity">

   <LinearLayout
       android:id="@+id/addLL"
       android:layout_width="match_parent"
       android:layout_height="wrap_content"
       android:orientation="horizontal">
       <EditText
           android:id="@+id/et01"
           android:hint="商品名称"
           android:layout_width="0dp"
           android:layout_height="wrap_content"
           android:layout_weight="1"/>
       <EditText
           android:id="@+id/et02"
           android:layout_width="0dp"
           android:layout_weight="1"
           android:layout_height="wrap_content"
           android:hint="金额"
           />
       <ImageView
           android:id="@+id/ivIcon1"
           android:layout_width="wrap_content"
           android:layout_height="wrap_content"
           android:onClick="add"
           android:src="@android:drawable/ic_input_add"
           />
   </LinearLayout>
    <ListView
        android:id="@+id/lv01"
        android:layout_width="match_parent"
        android:layout_height="match_parent"
        >

    </ListView>
</LinearLayout>
2.创建ListView布局

<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:orientation="horizontal">
    <TextView
        android:textColor="#000000"
        android:id="@+id/tvid"
        android:layout_width="0dp"
        android:layout_height="wrap_content"
        android:layout_weight="1"
        android:textSize="20sp"
        android:text="1"/>
    <TextView
        android:id="@+id/tvname"
        android:textColor="#000000"
        android:layout_width="0dp"
        android:layout_height="wrap_content"
        android:text="名称"
        android:textSize="20sp"
        android:layout_weight="2"/>
    <TextView
        android:textColor="#000000"
        android:id="@+id/tvprice"
        android:layout_width="0dp"
        android:layout_height="wrap_content"
        android:layout_weight="2"
        android:text="100"
        android:textSize="20sp"/>
<LinearLayout
    android:layout_width="wrap_content"
    android:layout_height="wrap_content"
    android:orientation="vertical">
    <ImageView

        android:id="@+id/ivup"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:layout_marginBottom="2dp"
        android:src="@android:drawable/arrow_up_float"/>
    <ImageView
        android:id="@+id/ivdown"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:src="@android:drawable/arrow_down_float"/>
</LinearLayout>
    <ImageView
        android:id="@+id/ivdelete"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:src="@android:drawable/ic_menu_delete"/>
</LinearLayout>

3.创建数据库。

public class MyHelper extends SQLiteOpenHelper {
    public MyHelper(Context context) {
        super(context, "db", null, 2);
    }//创建数据库db

    @Override
    public void onCreate(SQLiteDatabase db) {
        System.out.println("onCreate");
        //创建表名为account
        db.execSQL("create table account(_id integer primary key autoincrement,name varchar(20),balance integer)");

    }

    @Override
    public void onUpgrade(SQLiteDatabase db, int oldVersion, int newVersion) {
        System.out.println("onUpgrade");

    }
}
4.创建Account类。

public class Account {
    private Long id;
    private String name;
    private int balance;

    public Long getId() {
        return id;
    }

    public void setId(Long id) {
        this.id = id;
    }

    public String getName() {
        return name;
    }

    public void setName(String name) {
        this.name = name;
    }

    public int getBalance() {
        return balance;
    }

    public void setBalance(int balance) {
        this.balance = balance;
    }

    public Account(Long id, String name, int balance) {
        super();
        this.id = id;
        this.name = name;
        this.balance = balance;
    }
    public Account( String name, int balance) {
        super();
        this.name = name;
        this.balance = balance;
    }
    public Account() {
        super();

    }
    public String toString(){
        return "[序号："+id+",商品名称："+name+",余额："+balance+"]";
    }
}

5.创建数据操作类。
public class AccountDao {
    private MyHelper myHelper;
    public AccountDao(Context context){
        myHelper=new MyHelper(context);
    }
    //向数据库中插入数据操作
    public void  insert(Account account){
        //获取数据库对象
        SQLiteDatabase db=myHelper.getWritableDatabase();
        //用来装载用插入的数据
        ContentValues contentValues=new ContentValues();
        contentValues.put("name",account.getName());
        contentValues.put("balance",account.getBalance());
        long id=db.insert("account",null,contentValues);
        account.setId(id);
        db.close();
    }
    //数据库中根据id删除数据操作
    public int delete(long id){
        SQLiteDatabase db=myHelper.getWritableDatabase();
        int count=db.delete("account","_id=?",new String[] {id+""});
        db.close();
        return count;
    }
    //修改数据操作
    public int update(Account account){
        SQLiteDatabase db=myHelper.getWritableDatabase();
        ContentValues contentValues=new ContentValues();
        contentValues.put("name",account.getName());
        contentValues.put("balance",account.getBalance());
        int count=db.update("account",contentValues,"_id=?",new String[] {account.getId()+""});
        db.close();
        return count;
    }
    //查询数据操作
    public List<Account> queryAll(){
        SQLiteDatabase db=myHelper.getReadableDatabase();
        Cursor cursor=db.query("account",null,null,null,null,null,"balance DESC");
        List<Account> list=new ArrayList<Account>();
        while(cursor.moveToNext()){
            //可以根据列名获取索引
            long id=cursor.getLong(cursor.getColumnIndex("_id"));
            String name=cursor.getString(1);
            int balance=cursor.getInt(2);
            list.add(new Account(id,name,balance));
        }
        cursor.close();
        db.close();
        return list;
    }
}

6.编写界面交互代码：（MainActivity）
public class MainActivity extends Activity {
    //需要适配的数据集合
 private List<Account> list;
    //数据库增删改查操作类
    private AccountDao dao;
    //输入姓名的EditText
    private EditText nameET;
    //输入金额的EditText
    private EditText balanceET;
    //适配器
    private MyAdapter adapter;
    //ListView
    private ListView accountLV;
    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
        initView();
        dao=new AccountDao(this);
        list=dao.queryAll();
        adapter=new MyAdapter();
        accountLV.setAdapter(adapter);
    }
    private void initView(){
        accountLV=(ListView)findViewById(R.id.lv01);
        nameET=(EditText)findViewById(R.id.et01);
        balanceET=(EditText)findViewById(R.id.et02);
        accountLV.setOnItemClickListener(new MyOnItemClickListener());
    }
    public void add(View view){
        String name=nameET.getText().toString().trim();
        String balance=balanceET.getText().toString().trim();
        Account a=new Account(name,balance.equals("")?0:Integer.parseInt(balance));
        dao.insert(a);
        list.add(a);
        adapter.notifyDataSetChanged();
        accountLV.setSelection(accountLV.getCount()-1);
        nameET.setText("");
        balanceET.setText("");

    }
    private class MyAdapter extends BaseAdapter{

        @Override
        public int getCount() {
            return list.size();
        }

        @Override
        public Object getItem(int position) {
            return list.get(position);
        }

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

        @Override
        public View getView(int position, View convertView, ViewGroup parent) {
            View item=convertView!=null?convertView:View.inflate(getApplicationContext(),R.layout.listview_itemd,null);
            TextView tvid=(TextView)item.findViewById(R.id.tvid);
            TextView tvname=(TextView)item.findViewById(R.id.tvname);
            TextView tvbalance =(TextView)item.findViewById(R.id.tvprice);
            final Account a=list.get(position);
            tvid.setText(a.getId()+"");
            tvname.setText(a.getName());
            tvbalance.setText(a.getBalance()+"");
            ImageView ivup=(ImageView)item.findViewById(R.id.ivup);
            ImageView ivdown=(ImageView)item.findViewById(R.id.ivdown);
            ImageView ivdelete=(ImageView)item.findViewById(R.id.ivdelete);
            ivup.setOnClickListener(new View.OnClickListener() {
                @Override
                public void onClick(View view) {
                    a.setBalance(a.getBalance()+1);
                    notifyDataSetChanged();
                    dao.update(a);
                }
            });
            ivdown.setOnClickListener(new View.OnClickListener() {
                @Override
                public void onClick(View view) {
                    a.setBalance(a.getBalance()-1);
                    notifyDataSetChanged();
                    dao.update(a);
                }
            });
            ivdelete.setOnClickListener(new View.OnClickListener() {
                @Override
                public void onClick(View view) {
                    android.content.DialogInterface.OnClickListener listener=new android.content.DialogInterface.OnClickListener(){
                        public void onClick(DialogInterface dialogInterface,int which){
                            list.remove(a);
                            dao.delete(a.getId());
                            notifyDataSetChanged();

                        }
                    };
                    AlertDialog.Builder builder=new AlertDialog.Builder(MainActivity.this);
                    builder.setTitle("确定要删除吗?");
                    builder.setPositiveButton("确定",listener);
                    builder.setNegativeButton("取消",null);
                    builder.show();
                }
            });

            return item;
        }
    }
    private class  MyOnItemClickListener implements AdapterView.OnItemClickListener{

        @Override
        public void onItemClick(AdapterView<?> parent, View view, int position, long id) {
            Account a=(Account)parent.getItemAtPosition(position);
            Toast.makeText(getApplicationContext(),a.toString(),Toast.LENGTH_SHORT).show();
        }
    }
}

7.运行界面：