商品展示案例

1、界面展示

商品展示界面

<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:tools="http://schemas.android.com/tools"
xmlns:app="http://schemas.android.com/apk/res-auto"
android:id="@+id/activity_exe"
android:layout_width="match_parent"
android:layout_height="match_parent"
android:orientation="vertical"
tools:context="com.example.administrator.hello.Exe">

<LinearLayout
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:orientation="horizontal">

<TextView
android:layout_width="0dp"
android:layout_weight="1"
android:layout_marginTop="10dp"
android:layout_marginLeft="10dp"
android:layout_height="wrap_content"
android:hint="商品名称"/>
<TextView
android:layout_width="0dp"
android:layout_weight="1"
android:layout_marginTop="10dp"
android:layout_height="wrap_content"
android:hint="金额"/>
<ImageView
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:onClick="addgoods"
app:srcCompat="@android:drawable/ic_input_add"
android:id="@+id/imageView"
/>

</LinearLayout>

</LinearLayout>

listview界面

<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
android:layout_width="match_parent"
android:orientation="vertical"
android:layout_height="match_parent">

<LinearLayout
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:orientation="horizontal">
<EditText
android:layout_width="match_parent"

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android:layout_height="wrap_content"
android:id="@+id/tv_id"/>
<EditText
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:id="@+id/tv_name"/>
<EditText
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:id="@+id/tv_money"/>
<LinearLayout
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:orientation="vertical">
<ImageView
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:src="@android:drawable/arrow_up_float"
android:id="@+id/tv_up"/>
<ImageView
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:src="@android:drawable/arrow_down_float"
android:id="@+id/tv_down"/>
</LinearLayout>

<ImageView
android:layout_width="25dp"
android:layout_height="25dp"
android:src="@android:drawable/ic_menu_delete"
android:id="@+id/tv_delete"/>
</LinearLayout>
<ListView
android:id="@+id/ivgoods"
android:layout_width="wrap_content"
android:layout_height="wrap_content">

</ListView>
</LinearLayout>

2、mainActivbity代码如下

主要定义了构造方法

ublic class Exe extends AppCompatActivity {
private EditText etname;
private EditText etmoney;
private ListView ivgoods;
private Goodsdao goooddao;
private GoodsAdapter goodsAdapter;
private List<Gooods> goodsList;
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_exe);
etname= (EditText) findViewById(R.id.tv_name);
etmoney= (EditText) findViewById(R.id.tv_money);
ivgoods= (ListView) findViewById(R.id.ivgoods);
goooddao=new Goodsdao(this);
goooddao.queryAll();
goodsAdapter=new GoodsAdapter(this,R.layout.listview,goodsList);
}
public void addgoods(View view){
String name=etname.getText().toString();
String money=etmoney.getText().toString();

Gooods gooods=new Gooods(name,money,equals("")?0:Integer.parseInt(money));
goooddao.add(gooods);
goodsAdapter.notifyDataSetChanged();
Toast.makeText(this,"添加成功",Toast.LENGTH_LONG).show();
}
}

3、商品各个变量的定义

public class Gooods {
private Long id;
private String name;
private String money;

public Gooods(Long id, String name, Integer amount) {
this.id = id;
this.name = name;
this.money = money;
}

public Gooods(String money, String name) {
this.money = money;
this.name = name;
}

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 String getMoney() {
return money;
}

public void setMoney(String money) {
this.money = money;
}

@Override
public String toString() {
return "Gooods{" +
"id=" + id +
", name='" + name + '\'' +
", amount=" + money +
'}';
}
}

4、建立适配器GoodsAdapter

public class GoodsAdapter extends ArrayAdapter<Gooods>{
private int resourceid;
public GoodsAdapter(Context context, int resource,List<Gooods> objects) {

super(context, resource, objects);
resourceid=resource;
}

@NonNull
@Override
public View getView(int position, View convertView, ViewGroup parent) {
Gooods gooods=getItem(position);  //获取当前位置对应的商品
View view=null;
ViewHolder viewHolder;
if (convertView==null){
view=LayoutInflater.from(getContext()).inflate(R.layout.listview,null);
viewHolder=new ViewHolder();
viewHolder.tv_id= (TextView) view.findViewById(R.id.tv_id);
viewHolder.tv_name= (TextView) view.findViewById(R.id.tv_name);
viewHolder.tv_money= (TextView) view.findViewById(R.id.tv_money);
viewHolder.tv_up= (ImageView) view.findViewById(R.id.tv_up);
viewHolder.tv_down= (ImageView) view.findViewById(R.id.tv_down);
viewHolder.tv_delete= (ImageView) view.findViewById(R.id.tv_delete);
view.setTag(viewHolder);
}
else
{
view=convertView;
viewHolder= (ViewHolder) view.getTag();
}
viewHolder.tv_id.setText(gooods.getId()+"");
viewHolder.tv_name.setText(gooods.getName());
viewHolder.tv_money.setText(gooods.getMoney()+"");
return view;
}
class ViewHolder{
TextView tv_id;
TextView tv_name;
TextView tv_money;
ImageView tv_up;
ImageView tv_down;
ImageView tv_delete;

}
}

5、数据库连接

public class DBHelper extends SQLiteOpenHelper {
public static final String CREATE_GOODS="create table goods(_id integer primary key autoincrement,name varchar(20),money integer)";
public DBHelper(Context context, int version) {
super(context, "goods.db", null, version);
}

@Override
public void onCreate(SQLiteDatabase db) {
db.execSQL(CREATE_GOODS);
}

@Override
public void onUpgrade(SQLiteDatabase db, int oldVersion, int newVersion) {

}
}

6、数据的增删改查

public class Goodsdao {
private DBHelper dbHelper;

public Goodsdao(Context context){
dbHelper=new DBHelper(context,1);
}
public void add(Gooods goods){
SQLiteDatabase sqLiteDatabase=dbHelper.getWritableDatabase();
ContentValues values=new ContentValues();
values.put("name",goods.getName());
values.put("money",goods.getMoney());
sqLiteDatabase.insert("goods",null,values);
sqLiteDatabase.close();
}
public int delete(long  id){
SQLiteDatabase sqLiteDatabase=dbHelper.getWritableDatabase();
int count= sqLiteDatabase.delete("goods","_id=?",new String[]{id+""});
sqLiteDatabase.close();
return count;
}
public int update(Gooods goods){
SQLiteDatabase sqLiteDatabase=dbHelper.getWritableDatabase();
ContentValues values=new ContentValues();
values.put("name",goods.getName());
values.put("money",goods.getMoney());
int count=sqLiteDatabase.update("goods",values,"_id=?",new String[]{goods.getId()+""});

sqLiteDatabase.close();
return  count;
}
public List<Gooods>queryAll(){
List<Gooods> gooodsList=new ArrayList<>();
SQLiteDatabase sqLiteOpenHelper=dbHelper.getReadableDatabase();
Cursor cursor=sqLiteOpenHelper.query("goods",null,null,null,null,null,"money desc");
while (cursor.moveToNext()){
long id=cursor.getLong(cursor.getColumnIndex("id"));
String name=cursor.getString(cursor.getColumnIndex("name"));
int money=cursor.getInt(cursor.getColumnIndex("money"));
Gooods gooods=new Gooods(id,name,money);
gooodsList.add(gooods);
}
cursor.close();
sqLiteOpenHelper.close();
return gooodsList;
}
}

二、运行效果图

如图添加了一个商品 我们再添加一个看看

如图  2b铅笔 5元   现在我们删除这个商品

点击确定后】