<?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> package cn.itcase.yxy; 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; } } }