网站建设甲方给乙方的需求方案,孟州网站开发app,北京网站设计价格,光伏电站建设的行业网站该楼层疑似违规已被系统折叠 隐藏此楼查看此楼运行程序#xff0c;不知道为何点插入数据按钮会报错#xff0c;请万能的吧友帮我看看#xff0c;谢谢#xff0c;不废话#xff0c;直接上代码MainActivity.javapackage com.example.activity16;import android.support.v7.a…该楼层疑似违规已被系统折叠 隐藏此楼查看此楼运行程序不知道为何点插入数据按钮会报错请万能的吧友帮我看看谢谢不废话直接上代码MainActivity.javapackage com.example.activity16;import android.support.v7.app.ActionBarActivity;import android.content.ContentValues;import android.database.Cursor;import android.database.sqlite.SQLiteDatabase;import android.os.Bundle;import android.view.Menu;import android.view.MenuItem;import android.view.View;import android.view.View.OnClickListener;import android.widget.Button;public class MainActivity extends ActionBarActivity {private Button createButton;private Button upDatabaseButton;private Button insertButton;private Button updateButton; //声明private Button queryButton;Overrideprotected void onCreate(Bundle savedInstanceState) {super.onCreate(savedInstanceState);setContentView(R.layout.activity_main);createButton (Button)findViewById(R.id.createButton);upDatabaseButton(Button)findViewById(R.id.upDatabaseButton);insertButton(Button)findViewById(R.id.insertButton); //声明updateButton(Button)findViewById(R.id.updateButton);queryButton(Button)findViewById(R.id.queryButton);createButton.setOnClickListener(new CreateListener());upDatabaseButton.setOnClickListener(new UpDatabaseListener());insertButton.setOnClickListener(new InsertListener());updateButton.setOnClickListener(new UpdateListener());queryButton.setOnClickListener(new QueryListener());}class CreateListener implements OnClickListener{Overridepublic void onClick(View v) {DatabaseHelper dbHelpernew DatabaseHelper(MainActivity.this,tom_db, null, 1);SQLiteDatabase dbdbHelper.getReadableDatabase();//只用调用了这个方法才会创建打开数据库}}class UpDatabaseListener implements OnClickListener{Overridepublic void onClick(View v) {DatabaseHelper dbHelper new DatabaseHelper(MainActivity.this, tom_db, null, 2);SQLiteDatabase db dbHelper.getWritableDatabase();//更新数据库的版本}}class InsertListener implements OnClickListener{Overridepublic void onClick(View v) {System.out.println(insert);ContentValues values new ContentValues();values.put(id,1);values.put(name, jack);//values.put(id,2);//values.put(name, lili);DatabaseHelper dbHelpernew DatabaseHelper(MainActivity.this,tom_db,null,2);SQLiteDatabase dbdbHelper.getWritableDatabase();//获得一个可写的数据库db.insert(user, null, values);//调用insert方法把数据插入数据库中}}class UpdateListener implements OnClickListener{Overridepublic void onClick(View v) {System.out.println(update);ContentValues valuesnew ContentValues();values.put(name,Jim);DatabaseHelper dbHelper new DatabaseHelper(MainActivity.this,tom_db,null,2);SQLiteDatabase dbdbHelper.getWritableDatabase();db.update(user, values, id?, new String[]{2});}}class QueryListener implements OnClickListener{Overridepublic void onClick(View v) {DatabaseHelper dbHelper new DatabaseHelper(MainActivity.this,tom_db,null,2);SQLiteDatabase dbdbHelper.getReadableDatabase();Cursor cursor db.query(user, new String[]{id,name}, id?,new String[]{1}, null, null,null);while(cursor.moveToNext()){String namecursor.getString(cursor.getColumnIndex(name));System.out.println(query------name);}}}}DatabaseHelper.javapackage com.example.activity16;import android.content.Context;import android.database.sqlite.SQLiteDatabase;import android.database.sqlite.SQLiteDatabase.CursorFactory;import android.database.sqlite.SQLiteOpenHelper;public class DatabaseHelper extends SQLiteOpenHelper{private static final int VERSION1;public DatabaseHelper(Context context, String name, CursorFactory factory,int version) {super(context, name, factory, version);}//在SQLitOpenHelper的子类中必须有该构造函数Overridepublic void onCreate(SQLiteDatabase db) {//创建一个数据库System.out.println(create a DataBase);db.execSQL(create table user(id int name VARCHAR(20)));//execSQL函数用于执行SQL语句}Overridepublic void onUpgrade(SQLiteDatabase db, int oldVersion, int newVersion) {System.out.println(updatabase);}}关于布局的XML文件我就不发了请大神指点
