半期考试 二三题 (书籍维护 数据库）
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结构：
主活动xml
<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:app="http://schemas.android.com/apk/res-auto"
xmlns:tools="http://schemas.android.com/tools"
android:layout_width="match_parent"
android:layout_height="match_parent"
android:orientation="vertical"
tools:context=".MainActivity">
<ListView
android:id="@+id/listView"
android:layout_width="match_parent"
android:layout_height="0dp"
android:layout_weight="1" />
<Button
android:id="@+id/add"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_gravity="center"
android:onClick="btnAdd"
android:text="Add"
tools:ignore="OnClick" />
</LinearLayout>
MainActivity2 xml
<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:app="http://schemas.android.com/apk/res-auto"
xmlns:tools="http://schemas.android.com/tools"
android:layout_width="match_parent"
android:layout_height="match_parent"
android:orientation="vertical"
tools:context=".MainActivity2">
<EditText
android:id="@+id/book_name"
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:hint="输入书名：" />
<EditText
android:id="@+id/book_price"
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:hint="输入价格："
android:inputType="number"/>
<LinearLayout
android:layout_width="match_parent"
android:layout_height="wrap_content">
<LinearLayout
android:layout_width="0dp"
android:layout_height="wrap_content"
android:layout_weight="1">
<Button
android:id="@+id/button_cancel"
android:layout_width="wrap_content"
android:layout_height="match_parent"
android:onClick="cancel"
android:text="取消"
tools:ignore="OnClick" />
</LinearLayout>
<Button
android:id="@+id/button_ok"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:onClick="confirm"
android:text="确定"
tools:ignore="OnClick" />
</LinearLayout>
</LinearLayout>
书籍实体类
package com.example.second;
import java.io.Serializable;
public class Book implements Serializable
private String bookName;
private float bookPrice;
private int bookID;
public int getBookID()
return bookID;
public void setBookID(int bookID)
this.bookID = bookID;
public Book( String bookName, float bookPrice)
this.bookName = bookName;
this.bookPrice = bookPrice;
public Book(int bookID, String bookName, float bookPrice)
this.bookID = bookID;
this.bookName = bookName;
this.bookPrice = bookPrice;
public String getBookName()
return bookName;
public void setBookName(String bookName)
this.bookName = bookName;
public float getBookPrice()
return bookPrice;
public void setBookPrice(float bookPrice)
this.bookPrice = bookPrice;
数据库操作类：
package com.example.second;
import android.content.Context;
import android.database.sqlite.SQLiteDatabase;
import android.database.sqlite.SQLiteOpenHelper;
import androidx.annotation.Nullable;
public class SQLHelper extends SQLiteOpenHelper
public static final String BookTable = "book";
public SQLHelper(@Nullable Context context, @Nullable String name, @Nullable SQLiteDatabase.CursorFactory factory, int version)
super(context, name, factory, version);
@Override
public void onCreate(SQLiteDatabase db)
db.execSQL("create table book(_id integer primary key autoincrement,name text,price text)");
@Override
public void onUpgrade(SQLiteDatabase db, int oldVersion, int newVersion)
主活动 .java
package com.example.second;
import androidx.appcompat.app.AppCompatActivity;
import android.content.ContentValues;
import android.content.Intent;
import android.database.Cursor;
import android.database.sqlite.SQLiteDatabase;
import android.os.Bundle;
import android.view.MenuItem;
import android.view.View;
import android.widget.AdapterView;
import android.widget.CursorAdapter;
import android.widget.ListView;
import android.widget.PopupMenu;
import android.widget.SimpleCursorAdapter;
import java.util.ArrayList;
import java.util.List;
public class MainActivity extends AppCompatActivity
private SimpleCursorAdapter adpter;
private SQLiteDatabase db;
private SQLHelper sqlHelper;
private Cursor cursor;
private ListView listView;
private List<Book> bookList = new ArrayList<>();
private Intent intent;
@Override
protected void onCreate(Bundle savedInstanceState)
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
intent = new Intent(MainActivity.this,MainActivity2.class);
listView = findViewById(R.id.listView);
sqlHelper = new SQLHelper(this,"book.db",null,1);
db = sqlHelper.getWritableDatabase();//创建数据库
readDB();
cursor = db.query("book",null,null,null,null,null,null);
adpter = new SimpleCursorAdapter(this,android.R.layout.simple_list_item_2,cursor,new String[]"name","price",new int[]android.R.id.text1,android.R.id.text2, CursorAdapter.FLAG_REGISTER_CONTENT_OBSERVER);
listView.setAdapter(adpter);
listView.setOnItemClickListener(new AdapterView.OnItemClickListener()
@Override
public void onItemClick(AdapterView<?> parent, View view, final int position, long id)
PopupMenu popupMenu = new PopupMenu(MainActivity.this, view);
popupMenu.inflate(R.menu.main_menu);
popupMenu.show();
popupMenu.setOnMenuItemClickListener(new PopupMenu.OnMenuItemClickListener()
@Override
public boolean onMenuItemClick(MenuItem item)
switch (item.getItemId())
case R.id.edit:
intent.putExtra("position",position);
intent.putExtra("bookToUpdate",bookList.get(position));
// startActivityForResult(intent,1);
break;
case R.id.delete:
String bookName = bookList.get(position).getBookName();
db.delete(SQLHelper.BookTable,"name=?",new String[]bookName);
reload();
break;
return true;
);
);
private void readDB()
Cursor c = sqlHelper.getReadableDatabase().rawQuery("select * from book", null);
int columnSize = c.getColumnCount();
while(c.moveToNext())
for(int i=0;i<columnSize;i++)
bookList.add(new Book(c.getInt(0),c.getString(1),c.getFloat(2)));
private void reload()
Cursor cursor = db.query(SQLHelper.BookTable,null,null,null,null,null,null,null);
adpter.swapCursor(cursor);
public void btnAdd(View v)
//Intent intent = new Intent(MainActivity.this,Main2Activity.class);
startActivityForResult(intent,1);
@Override
protected void onActivityResult(int requestCode, int resultCode, Intent data)
super.onActivityResult(requestCode, resultCode, data);
if(requestCode ==1)
if(resultCode==RESULT_OK)
Book book = (Book) data.getSerializableExtra("book");
int position = (Integer)data.getIntExtra("position",0);
if(book!=null)
ContentValues contentValues = new ContentValues();
contentValues.put("name",book.getBookName());
contentValues.put("price",book.getBookPrice());
db.insert(SQLHelper.BookTable,null,contentValues);
reload();
readDB();
MainActivity2 .java
package com.example.second;
import androidx.appcompat.app.AppCompatActivity;
import android.content.Intent;
import android.os.Bundle;
import android.view.View;
import android.widget.EditText;
import android.widget.Toast;
public class MainActivity2 extends AppCompatActivity
private EditText book_name;
private EditText book_price;
private int position;
private String bookName;
private String bookPrice;
@Override
protected void onCreate(Bundle savedInstanceState)
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main2);
book_name = findViewById(R.id.book_name);
book_price = findViewById(R.id.book_price);
public void cancel(View view)
book_name.setText("");
book_price.setText("");
// 结束当前窗口的生命周期
finish();
public void confirm(View v)
bookName = book_name.getText().toString();
bookPrice = book_price.getText().toString(以上是关于半期考试 二三题 (书籍维护 数据库）的主要内容，如果未能解决你的问题，请参考以下文章