package com.example.myapplication;
import androidx.appcompat.app.AppCompatActivity;
import android.content.ContentValues;
import android.database.Cursor;
import android.database.sqlite.SQLiteDatabase;
import android.os.Bundle;
import android.util.Log;
import android.view.View;
import android.widget.Button;
import android.widget.EditText;
import android.widget.ListView;
import android.widget.Toast;
import java.util.ArrayList;
import java.util.List;
public class MainActivity extends AppCompatActivity implements View.OnClickListener{
private EditText et_name,et_price,et_number;
private ListView listView;
private String name,price,number;
private MyHelper myHelper;
private SQLiteDatabase db;
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
et_name = (EditText)findViewById(R.id.et_name);
et_price = (EditText)findViewById(R.id.et_price);
et_number = (EditText) findViewById(R.id.et_number);
listView = (ListView)findViewById(R.id.listView);
Button add = (Button)findViewById(R.id.add);
Button query =(Button) findViewById(R.id.query);
Button update =(Button) findViewById(R.id.update);
Button delete = (Button)findViewById(R.id.delete);
add.setOnClickListener(this);
query.setOnClickListener(this);
update.setOnClickListener(this);
delete.setOnClickListener(this);
myHelper = new MyHelper(this);
}
public void onClick(View v) {
switch (v.getId()){
case R.id.add:
db = myHelper.getWritableDatabase();
name = et_name.getText().toString();
price = et_price.getText().toString();
number = et_number.getText().toString();
ContentValues values = new ContentValues(); //创建ContentValues对象
values.put("name", name); //将数据添加到ContentValues对象
values.put("price", price);
values.put("number", number);
db.insert("cart", null, values);
db.close();
Toast.makeText(this, "信息已添加", Toast.LENGTH_SHORT).show();
break;
case R.id.query:
Log.e("yanwenhua","123");
List<CartBean> list = new ArrayList();
db = myHelper.getWritableDatabase();
Cursor cursor = db.query("cart", null, null, null, null,
null, null);
if (cursor.getCount() == 0) {
Toast.makeText(this, "没有数据", Toast.LENGTH_SHORT).show();
} else {
while (cursor.moveToNext()) {
CartBean cartBean = new CartBean();
int nameIndex = cursor.getColumnIndex("name");
int priceIndex = cursor.getColumnIndex("price");
int numberIndex = cursor.getColumnIndex("number");
String name = cursor.getString(nameIndex);
String price = cursor.getString(priceIndex);
String number = cursor.getString(numberIndex);
Log.e("yanwenhua","cursor.getCount();--"+cursor.getCount()+"name-"+name+" "+price+" "+number);
cartBean.setName(name);
cartBean.setPrice(price);
cartBean.setNumber(number);
list.add(cartBean);
}
CartAdapter adapter = new CartAdapter(MainActivity.this,list);
listView.setAdapter(adapter);
adapter.notifyDataSetChanged();
}
cursor.close();
db.close();
break;
case R.id.update:
name = et_name.getText().toString();
price = et_price.getText().toString();
number = et_number.getText().toString();
db = myHelper.getWritableDatabase();
values = new ContentValues(); // 要修改的数据
values.put("number",number);
values.put("price",price);
db.update("cart", values, "name=?",
new String[]{name}); // 更新并得到行数
db.close();
Toast.makeText(this, "信息已修改", Toast.LENGTH_SHORT).show();
break;
case R.id.delete:
db = myHelper.getWritableDatabase();
db.delete("cart", null, null);
List<CartBean> list2 = new ArrayList();
CartAdapter adapter = new CartAdapter(MainActivity.this,list2);
listView.setAdapter(adapter);
adapter.notifyDataSetChanged();
db.close();
Toast.makeText(this, "信息已删除", Toast.LENGTH_SHORT).show();
break;
}
}
}
package com.example.myapplication;
import android.content.Context;
import android.util.Log;
import android.view.LayoutInflater;
import android.view.View;
import android.view.ViewGroup;
import android.widget.BaseAdapter;
import android.widget.TextView;
import java.util.List;
class CartAdapter extends BaseAdapter {
private List<CartBean> list;
private LayoutInflater layoutInflater;
public CartAdapter(Context context, List<CartBean> list){
this.layoutInflater = LayoutInflater.from(context);
this.list = list;
}
@Override
public int getCount() {
Log.e("yanwenhua","list.size()--"+list.size());
return list.size();
}
@Override
public Object getItem(int position) {
return null;
}
@Override
public long getItemId(int position) {
return 0;
}
@Override
public View getView(int position, View convertView, ViewGroup parent) {
ViewHolder viewHolder;
if (convertView==null){
convertView=layoutInflater.inflate(R.layout.listview_item,null);
viewHolder=new ViewHolder(convertView);
convertView.setTag(viewHolder);
}else {
viewHolder=(ViewHolder) convertView.getTag();
}
CartBean cartBean = list.get(position);
viewHolder.tv_name.setText("商品名称："+cartBean.getName());
viewHolder.tv_price.setText("商品价格："+cartBean.getPrice());
viewHolder.tv_number.setText("商品数量："+cartBean.getNumber());
Log.e("yanwenhua","cartBean.getName()-"+cartBean.getName()+" "+cartBean.getPrice()+" "+cartBean.getNumber());
return convertView;
}
class ViewHolder{
TextView tv_name;
TextView tv_price;
TextView tv_number;
public ViewHolder(View view){
tv_name = (TextView) view.findViewById(R.id.tv_name);
tv_price = (TextView) view.findViewById(R.id.tv_price);
tv_number = (TextView) view.findViewById(R.id.tv_number);
}
}
}
package com.example.myapplication;
class CartBean {
private String name;
private String price;
private String number;
public String getName() {
return name;
}
public void setName(String name) {
this.name = name;
}
public String getPrice() {
return price;
}
public void setPrice(String price) {
this.price = price;
}
public String getNumber() {
return number;
}
public void setNumber(String number) {
this.number = number;
}
}
package com.example.myapplication;
import android.content.Context;
import android.database.sqlite.SQLiteDatabase;
import android.database.sqlite.SQLiteOpenHelper;
class MyHelper extends SQLiteOpenHelper {
public MyHelper(Context context) {
super(context, "shoppingcart.db", null, 1);
}
@Override
public void onCreate(SQLiteDatabase db) {
db.execSQL("CREATE TABLE cart(_id INTEGER PRIMARY KEY AUTOINCREMENT, name VARCHAR(20), price VARCHAR(20), number VARCHAR(20))");
}
@Override
public void onUpgrade(SQLiteDatabase db, int oldVersion, int newVersion) {
}
}
<?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="#E6E6E6"
android:orientation="vertical"
android:padding="10dp">
<LinearLayout
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:layout_marginTop="15dp"
android:background="@android:color/white"
android:orientation="horizontal">
<TextView
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:padding="10dp"
android:text="名称:"
android:textColor="#000"
android:textSize="20sp" />
<EditText
android:id="@+id/et_name"
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:layout_marginLeft="5dp"
android:background="@null"
android:padding="10dp"
android:maxLines="1"/>
</LinearLayout>
<LinearLayout
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:layout_marginTop="15dp"
android:background="@android:color/white"
android:orientation="horizontal">
<TextView
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:padding="10dp"
android:text="价格:"
android:textColor="#000"
android:textSize="20sp" />
<EditText
android:id="@+id/et_price"
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:layout_marginLeft="5dp"
android:background="@null"
android:padding="10dp"
android:maxLines="1"/>
</LinearLayout>
<LinearLayout
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:layout_marginTop="10dp"
android:background="@android:color/white"
android:orientation="horizontal">
<TextView
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:padding="10dp"
android:text="数量:"
android:textColor="#000"
android:textSize="20sp" />
<EditText
android:id="@+id/et_number"
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:layout_marginLeft="5dp"
android:background="@null"
android:padding="10dp"
android:maxLines="1"/>
</LinearLayout>
<LinearLayout
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:orientation="horizontal"
android:layout_marginTop="10dp">
<Button
android:id="@+id/add"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:text="添加"/>
<Button
android:id="@+id/query"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:text="查询"/>
<Button
android:id="@+id/update"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:text="修改"/>
<Button
android:id="@+id/delete"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:text="删除"/>
</LinearLayout>
<ListView
android:id="@+id/listView"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:background="#ffffff">
</ListView>
</LinearLayout>
<?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:orientation="vertical"
android:padding="10dp">
<TextView
android:id="@+id/tv_name"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:textSize="15sp"/>
<TextView
android:id="@+id/tv_price"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_marginTop="3dp"
android:textSize="15sp"/>
<TextView
android:id="@+id/tv_number"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_marginTop="3dp"
android:textSize="15sp"/>
</LinearLayout>
