ListView控件---商品展示案例

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().t
ab44
oString().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：