我是android开发的新手。我正在尝试更新数据库行，但是每次我使用 db.update(DATABASE_TABLE, args,KEY_ROWID+"="+rowId, null) 时都会得到 0 作为回报
package com.multi.xxxxx;
import android.content.ContentValues;
import android.content.Context;
import android.database.Cursor;
import android.database.SQLException;
import android.database.sqlite.SQLiteDatabase;
import android.database.sqlite.SQLiteOpenHelper;
import android.util.Log;
public class DBAdapter {
public static final String KEY_ROWID = "_id";
public static final String KEY_ISBN = "isbn";
public static final String KEY_TITLE = "title";
public static final String KEY_PUBLISHER = "publisher";
private static final String TAG = "DBAdapter";
// private static final String DATABASE_NAME = "books";
// private static final String DATABASE_TABLE = "titles";
public static final String DATABASE_NAME = "books";
public static final String DATABASE_TABLE = "titles";
private static final int DATABASE_VERSION = 1;
private static final String DATABASE_CREATE =
"create table titles (_id integer primary key autoincrement, "
+ "isbn text not null, title integer not null, "
+ "publisher text not null);";
private final Context context;
private DatabaseHelper DBHelper;
private SQLiteDatabase db;
public DBAdapter(Context ctx)
{
this.context = ctx;
DBHelper = new DatabaseHelper(context);
}
private static class DatabaseHelper extends SQLiteOpenHelper
{
DatabaseHelper(Context context)
{
super(context, DATABASE_NAME, null, DATABASE_VERSION);
}
@Override
public void onCreate(SQLiteDatabase db)
{
db.execSQL(DATABASE_CREATE);
}
@Override
public void onUpgrade(SQLiteDatabase db, int oldVersion, int newVersion)
{
Log.w(TAG, "Upgrading database from version " + oldVersion
+ " to "
+ newVersion + ", which will destroy all old data");
db.execSQL("DROP TABLE IF EXISTS titles");
onCreate(db);
}
}
//---opens the database---
public DBAdapter open() throws SQLException
{
db = DBHelper.getWritableDatabase();
return this;
}
//---closes the database---
public void close()
{
DBHelper.close();
}
//---insert a title into the database---
public long insertTitle(String isbn, String title, String publisher)
{
ContentValues initialValues = new ContentValues();
initialValues.put(KEY_ISBN, isbn);
initialValues.put(KEY_TITLE, title);
initialValues.put(KEY_PUBLISHER, publisher);
return db.insert(DATABASE_TABLE, null, initialValues);
}
//---deletes a particular title---
public boolean deleteTitle(long rowId)
{
return db.delete(DATABASE_TABLE, KEY_ROWID +
"=" + rowId, null) > 0;
}
//---retrieves all the titles---
public Cursor getAllTitles()
{
return db.query(DATABASE_TABLE, new String[] {
KEY_ROWID,
KEY_ISBN,
KEY_TITLE,
KEY_PUBLISHER
},
null,
null,
null,
null,
null);
}
//---retrieves a particular title---
public Cursor getTitle(long rowId) throws SQLException
{
Cursor mCursor =
db.query(true, DATABASE_TABLE, new String[] {
KEY_ROWID,
KEY_ISBN,
KEY_TITLE,
KEY_PUBLISHER
},
KEY_ROWID + "=" + rowId,
null,
null,
null,
null,
null);
if (mCursor != null) {
mCursor.moveToFirst();
}
return mCursor;
}
//---updates a title---
public boolean updateTitle(long rowId, String isbn, String title, String publisher)
{
ContentValues args = new ContentValues();
args.put(KEY_ISBN, isbn);
args.put(KEY_TITLE, title);
args.put(KEY_PUBLISHER, publisher);
return db.update(DATABASE_TABLE, args,
KEY_ROWID+"="+rowId, null) > 0;
}
}
从下面的类调用上面类的更新方法
package com.multi.xxxx;
import android.app.Activity;
import android.database.Cursor;
import android.os.Bundle;
import android.view.Menu;
import android.view.View;
import android.view.View.OnClickListener;
import android.widget.Button;
import android.widget.EditText;
import android.widget.Toast;
import android.util.Log;
public class DatabaseUpdateActivity extends Activity {
EditText edit1,edit2,edit3;
Button update;
Button delete;
public static long rowID;
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_add_contacts);
final DBAdapter db = new DBAdapter(this);
db.open();
edit1=(EditText)findViewById(R.id.et_name);
edit2=(EditText)findViewById(R.id.et_mobile_phone);
edit3=(EditText)findViewById(R.id.et_work_email);
update = (Button) findViewById(R.id.btn_add);
delete = (Button) findViewById(R.id.btn_contacts);
update.setText("Update");
delete.setText("Delete");
int id = (int)rowID;
//Cursor c = db.getTitle(rowID);
Cursor c = db.getAllTitles();
c.moveToFirst();
if (c != null && c.moveToFirst()) Log.d("cursor = ", c.getString(c.getColumnIndex(DBAdapter.KEY_ISBN)));
if (c != null)
{
c.moveToPosition(id);
edit1.setText(c.getString(c.getColumnIndex(DBAdapter.KEY_ISBN)));
edit2.setText(c.getString(c.getColumnIndex(DBAdapter.KEY_TITLE)));
edit3.setText(c.getString(c.getColumnIndex(DBAdapter.KEY_PUBLISHER)));
}
update.setOnClickListener(new OnClickListener() {
@Override
public void onClick(View v) {
// TODO Auto-generated method stub
String editText1=edit1.getText().toString();
String editText2=edit2.getText().toString();
String editText3=edit3.getText().toString();
//long result=db.insertTitle(editText1, editText2, editText3);
//long result;
if ( editText2.isEmpty() == false)
{
boolean isUpdated = db.updateTitle(rowID,editText1,editText2, editText3);
db.updateTitle(rowID,editText1,editText2, editText3);
if (isUpdated == true)
{
Toast.makeText(DatabaseUpdateActivity.this,"DataUpdated",Toast.LENGTH_LONG).show();
edit1.setText("");
edit2.setText("");
edit3.setText("");
finish();
}
}
else
Toast.makeText(DatabaseUpdateActivity.this,"Fill Phone Number",Toast.LENGTH_LONG).show();
}
});
delete.setOnClickListener(new OnClickListener() {
@Override
public void onClick(View v) {
// TODO Auto-generated method stub
boolean isDeleted = db.deleteTitle(rowID);
if (isDeleted == true)
{
Toast.makeText(DatabaseUpdateActivity.this,"DataDeleted",Toast.LENGTH_LONG).show();
finish();
}
}
});
}
@Override
public boolean onCreateOptionsMenu(Menu menu) {
// Inflate the menu; this adds items to the action bar if it is present.
getMenuInflater().inflate(R.menu.database_update, menu);
return true;
}
public void setRowId(long id) {
rowID = id;
}
}
这是我使用该代码的链接， 我搜索了很多但无法找到令人满意的答案。