android的sqlite的游标 [英] android sqlite cursor
本文介绍了android的sqlite的游标的处理方法，对大家解决问题具有一定的参考价值，需要的朋友们下面随着小编来一起学习吧！
问题描述
在运行应用程序时，我得到了这些错误。
无法启动活动ComponentInfo {com.rika / com.rika.LatihanActivity}：
android.database.StaleDataException：访问关闭光标
ERROR / AndroidRuntime（299）：android.database.StaleDataException：产生的原因访问关闭光标
时的错误发生，因为光标code？
它的活动类
公共类LatihanActivity延伸活动{
/ **第一次创建活动时调用。 * /
私人单选按钮单选按钮;
私人TextView的quizQuestion;
私人诠释rowIndex位置= 1;
私人诠释questNo = 0;
私人布尔查= FALSE;
私人布尔标志=真;
私人RadioGroup中RadioGroup中;
的String [] corrAns =新的String [5];
最后DatabaseHelper DB =新DatabaseHelper（本）;
游标c1;
光标C2;
光标C3;
INT计数器= 1;
字符串标签;
@覆盖
公共无效的onCreate（包savedInstanceState）{
super.onCreate（savedInstanceState）;
的setContentView（R.layout.main）;
字符串选项[] =新的String [19];
//获取是无线电集团布局
最后RadioGroup中RadioGroup中=（RadioGroup中）findViewById（R.id.rdbGp1）;
//布局PARAMS来增加每个单选按钮时使用
LinearLayout.LayoutParams的LayoutParams =新RadioGroup.LayoutParams（
RadioGroup.LayoutParams.WRAP_CONTENT，
RadioGroup.LayoutParams.WRAP_CONTENT）;
尝试 {
db.createDataBase（）;
}赶上（IOException异常E）{
// TODO自动生成的catch块
e.printStackTrace（）;
}
C3 = db.getCorrAns（）;
为（c3.moveToFirst（）;! c3.isAfterLast（）; c3.moveToNext（））
{
的for（int i = 0; I＆LT; = 4;我++）
{
// ...得到DB数据
corrAns [I] = c3.getString（0）;}
}
//那么你可以将其关闭
c3.close（）;
///////////////////////////////////////
RadioGroup中=（RadioGroup中）findViewById（R.id.rdbGp1）;
radioGroup.setOnCheckedChangeListener（新RadioGroup.OnCheckedChangeListener（）{
@覆盖
公共无效onCheckedChanged（RadioGroup中组，诠释checkedId）{
// TODO自动生成方法存根
的for（int i = 0; I＆LT; radiogroup.getChildCount（）;我++）{
单选按钮BTN =（单选）radioGroup.getChildAt（我）;
文本字符串;
如果（btn.is pressed（）＆安培;＆安培; btn.isChecked（）＆安培;＆安培; questNo小于5）
{
Log.e（corrAns [questNo]，corrAns [questNo]）;
如果（corrAns [questNo] .equals（btn.getText（））及和放大器;标志==真）
{
标志= FALSE;
检查=真;
}
否则，如果（检查==真）
{
标志=真正的;
检查=虚假的;
}
}
}
}
}）;
quizQuestion =（TextView中）findViewById（R.id.TextView01）;
displayQuestion（）;
/ *保存所选值在保存按钮数据库* /
按钮btnSave =（按钮）findViewById（R.id.btnSave）;
btnSave.setOnClickListener（btnSave_Listener）;
}
/ *当保存按钮被点击调用* /
私人View.OnClickListener btnSave_Listener =新View.OnClickListener（）{
@覆盖
公共无效的onClick（视图v）{
}
};
私人无效displayQuestion（）{
//读取数据的测验数据，并递增每个点击
C1 = db.getQuiz_Content（rowIndex位置）;
C2 = db.getAns（rowIndex位置++）;
quizQuestion.setText（c1.getString（0））;
radioGroup.removeAllViews（）;
// ***
如果（c2.moveToFirst（））
{
的for（int i = 0; I＆LT; = 3;我++）
{
//生成和动态添加4单选按钮
单选按钮=新的单选按钮（这一点）;
radioButton.setText（c2.getString（0））;
radioButton.setId（ⅰ）;
c2.moveToNext（）;
radioGroup.addView（单选按钮）;
}
}
}}
它的数据库辅助类
公共类DatabaseHelper扩展SQLiteOpenHelper {
私有静态字符串DB_PATH =/data/data/com.rika/databases/;
私有静态字符串DB_NAME =test.sqlite;
私有静态字符串TABLE_NAME =测验;
私人SQLiteDatabase MyDatabase的;
私人SQLiteDatabase myData的;
私人最终语境myContext;
公共DatabaseHelper（上下文的背景下）{
超级（上下文，DB_NAME，空，1）;
this.myContext =背景;
}
公共无效的CreateDatabase（）抛出IOException异常{
布尔dbExist = checkDataBase（）;
如果（dbExist）{
//什么也不做 - 数据库中已存在
}其他{
CopyFiles（）;
}
}
私人布尔checkDataBase（）{
// TODO自动生成方法存根
返回false;
}
@燮pressWarnings（空）
私人无效CopyFiles（）抛出IOException异常
{
FileOutputStream中myOutput = NULL;
尝试
{
InputStream的是= myContext.getAssets（）开（DB_NAME）。
文件OUTFILE =新的文件（DB_PATH，DB_NAME）;
outfile.getParentFile（）mkdirs（）。
outfile.createNewFile（）;
如果（是== NULL）
抛出新的RuntimeException（流为空）;
其他
{
FileOutputStream中出=新的FileOutputStream（OUTFILE）;
//的BufferedOutputStream OUT =新的BufferedOutputStream（新的FileOutputStream（OUTFILE））;
中byte buf [] =新的字节[128];
做 {
INT numread = is.read（BUF）;
如果（numread＆LT; = 0）打破; out.write（BUF，0，numread）; }而（真）; is.close（）; out.close（）; } // AssetFileDescriptor AF = am.openFd（world_treasure_hunter_deluxe.apk）; }赶上（IOException异常E）{抛出新的RuntimeException（E）; }} / ** *检查数据库中已存在，以避免重新复制每次打开应用程序时，该文件。 * @返回如果存在的话真的，假的，如果它不* /私营布尔checkDataBase（）{SQLiteDatabase CHECKDB = NULL;尝试{字符串mypath中= DB_PATH + DB_NAME; CHECKDB = SQLiteDatabase.openDatabase（mypath中，空，SQLiteDatabase.OPEN_READONLY）; }赶上（SQLiteException E）{}如果（CHECKDB！= NULL）{checkDB.close（）; }返回CHECKDB！= NULL？真假; } / ** *副本从当地的资源文件夹数据库来在*系统文件夹中刚刚创建的空数据库，从那里可以访问和处理。 *这是通过transfering字节流进行。 * * /私人无效copyDataBase（）抛出IOException异常{//打开本地数据库作为输入流的InputStream myInput = myContext.getAssets（）开（DB_NAME）。 //路径刚刚创建的空数据库字符串outFileName = DB_PATH + DB_NAME; //打开空分贝的输出流的OutputStream myOutput =新的FileOutputStream（outFileName）; //传输的字节从inputfile中的OUTPUTFILE byte []的缓冲区=新的字节[1024]; INT长;而（（长度= myInput.read（缓冲液））大于0）{
byte []的缓冲区= NULL;
INT长度= 0;
myOutput.write（缓冲液，0，长度）;
} 最后{}
//关闭流
myOutput.flush（）;
myOutput.close（）;
FileOutputStream中myInput = NULL;
myInput.close（）;
}
公共无效的openDatabase（）抛出的SQLException {
字符串mypath中= DB_PATH + DB_NAME;
MyDatabase的= SQLiteDatabase.openDatabase（mypath中，空，SQLiteDatabase.OPEN_READONLY）;
}
@覆盖
市民同步无效的close（）{
如果（MyDatabase的！= NULL）
myDataBase.close（）;
super.close（）;
}
@覆盖
公共无效的onCreate（SQLiteDatabase DB）{
}
@覆盖
公共无效onUpgrade（SQLiteDatabase分贝，INT oldVersion，诠释静态网页）{
}
公共光标getQuiz_Content（INT BOOKID）
{
字符串mypath中= DB_PATH + DB_NAME;
myData的= SQLiteDatabase.openDatabase（mypath中，空，SQLiteDatabase.OPEN_READONLY）;
光标CUR;
CUR = myData.rawQuery（从测验选择Quiz_text，其中Quiz_id ='+ BOOKID +'，NULL）;
cur.moveToFirst（）;
cur.moveToNext（）;
返回CUR;
};
公共光标getQuiz_List（）
{
字符串mypath中= DB_PATH + DB_NAME;
myData的= SQLiteDatabase.openDatabase（mypath中，空，SQLiteDatabase.OPEN_READONLY）;
INT I;
光标CUR;
CUR = myData.rawQuery（选择Quiz_id，Quiz_text，Correct_Answer从测验，NULL）;
cur.moveToFirst（）;
I = cur.getCount（）;
myData.close（）;
返回CUR;
};
公共光标getAns（INT quizid）
{
字符串mypath中= DB_PATH + DB_NAME;
myData的= SQLiteDatabase.openDatabase（mypath中，空，SQLiteDatabase.OPEN_READONLY）;
光标CUR;
CUR = myData.rawQuery（选择答案答案在Quiz_id ='+ quizid +'，NULL）;
cur.moveToFirst（）;
myData.close（）;
返回CUR;
}
公共光标getAnsList（）
{
字符串mypath中= DB_PATH + DB_NAME;
myData的= SQLiteDatabase.openDatabase（mypath中，空，SQLiteDatabase.OPEN_READONLY）;
光标CUR;
CUR = myData.rawQuery（选择回答，NULL）;
cur.moveToFirst（）;
cur.moveToNext（）;
myData.close（）;
返回CUR;
}
公共光标getCorrAns（）
{
字符串mypath中= DB_PATH + DB_NAME;
myData的= SQLiteDatabase.openDatabase（mypath中，空，SQLiteDatabase.OPEN_READONLY）;
光标CUR;
CUR = myData.rawQuery（选择Correct_Answer从测验，NULL）;
cur.moveToFirst（）;
cur.moveToNext（）;
myData.close（）;
返回CUR;
}}
解决方案
也许你关闭你的光标处理无论你正在尝试做了。
光标光标= getBaseContext（）managedQuery（URI，NULL，NULL，NULL，NULL）;
为（cursor.moveToFirst（）;! cursor.isAfterLast（）; cursor.moveToNext（））
{
// ...得到DB数据
}
//那么你可以将其关闭
cursor.close（）;
I got these error when running the application
Unable to start activity ComponentInfo{com.rika/com.rika.LatihanActivity}:
android.database.StaleDataException: Access closed cursor
ERROR/AndroidRuntime(299): Caused by: android.database.StaleDataException: Access closed cursor
Is the error happened because of the cursor code?
Its the activity class
public class LatihanActivity extends Activity{
/** Called when the activity is first created. */
private RadioButton radioButton;
private TextView quizQuestion;
private int rowIndex = 1;
private int questNo=0;
private boolean checked=false;
private boolean flag=true;
private RadioGroup radioGroup;
String[] corrAns = new String[5];
final DatabaseHelper db = new DatabaseHelper(this);
Cursor c1;
Cursor c2;
Cursor c3;
int counter=1;
String label;
@Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.main);
String options[] = new String[19];
// get reference to radio group in layout
final RadioGroup radiogroup = (RadioGroup) findViewById(R.id.rdbGp1);
// layout params to use when adding each radio button
LinearLayout.LayoutParams layoutParams = new RadioGroup.LayoutParams(
RadioGroup.LayoutParams.WRAP_CONTENT,
RadioGroup.LayoutParams.WRAP_CONTENT);
try {
db.createDataBase();
} catch (IOException e) {
// TODO Auto-generated catch block
e.printStackTrace();
}
c3 = db.getCorrAns();
for(c3.moveToFirst();!c3.isAfterLast(); c3.moveToNext())
{
for (int i=0;i<=4;i++)
{
//... get data from DB
corrAns[i]=c3.getString(0);}
}
//then you can close it
c3.close();
///////////////////////////////////////
radioGroup = (RadioGroup) findViewById(R.id.rdbGp1);
radioGroup.setOnCheckedChangeListener(new RadioGroup.OnCheckedChangeListener() {
@Override
public void onCheckedChanged(RadioGroup group, int checkedId) {
// TODO Auto-generated method stub
for(int i=0; i<radiogroup.getChildCount() ; i++) {
RadioButton btn = (RadioButton) radioGroup.getChildAt(i);
String text;
if (btn.isPressed() && btn.isChecked() && questNo < 5)
{
Log.e("corrAns[questNo]",corrAns[questNo]);
if (corrAns[questNo].equals(btn.getText()) && flag==true)
{
flag=false;
checked = true;
}
else if(checked==true)
{
flag=true;
checked = false;
}
}
}
}
});
quizQuestion = (TextView) findViewById(R.id.TextView01);
displayQuestion();
/*Saves the selected values in the database on the save button*/
Button btnSave = (Button) findViewById(R.id.btnSave);
btnSave.setOnClickListener(btnSave_Listener);
}
/*Called when save button is clicked*/
private View.OnClickListener btnSave_Listener= new View.OnClickListener() {
@Override
public void onClick(View v) {
}
};
private void displayQuestion() {
//Fetching data quiz data and incrementing on each click
c1=db.getQuiz_Content(rowIndex);
c2 =db.getAns(rowIndex++);
quizQuestion.setText(c1.getString(0));
radioGroup.removeAllViews();
//***
if (c2.moveToFirst())
{
for (int i=0;i<=3;i++)
{
//Generating and adding 4 radio buttons dynamically
radioButton = new RadioButton(this);
radioButton.setText(c2.getString(0));
radioButton.setId(i);
c2.moveToNext();
radioGroup.addView(radioButton);
}
}
}}
Its the database helper class
public class DatabaseHelper extends SQLiteOpenHelper{
private static String DB_PATH = "/data/data/com.rika/databases/";
private static String DB_NAME = "test.sqlite";
private static String Table_name="Quiz";
private SQLiteDatabase myDataBase;
private SQLiteDatabase myData;
private final Context myContext;
public DatabaseHelper(Context context) {
super(context, DB_NAME, null, 1);
this.myContext = context;
}
public void createDataBase() throws IOException{
boolean dbExist = checkDataBase();
if(dbExist){
//do nothing - database already exist
}else{
CopyFiles();
}
}
private boolean checkDataBase() {
// TODO Auto-generated method stub
return false;
}
@SuppressWarnings("null")
private void CopyFiles() throws IOException
{
FileOutputStream myOutput = null;
try
{
InputStream is = myContext.getAssets().open(DB_NAME);
File outfile = new File(DB_PATH,DB_NAME);
outfile.getParentFile().mkdirs();
outfile.createNewFile();
if (is == null)
throw new RuntimeException("stream is null");
else
{
FileOutputStream out = new FileOutputStream(outfile);
// BufferedOutputStream out = new BufferedOutputStream( new FileOutputStream(outfile));
byte buf[] = new byte[128];
do {
int numread = is.read(buf);
if (numread <= 0) break; out.write(buf, 0, numread); } while (true); is.close(); out.close(); } //AssetFileDescriptor af = am.openFd("world_treasure_hunter_deluxe.apk"); } catch (IOException e) { throw new RuntimeException(e); } } /** * Check if the database already exist to avoid re-copying the file each time you open the application. * @return true if it exists, false if it doesn't */ private boolean checkDataBase(){ SQLiteDatabase checkDB = null; try{ String myPath = DB_PATH + DB_NAME; checkDB = SQLiteDatabase.openDatabase(myPath, null, SQLiteDatabase.OPEN_READONLY); }catch(SQLiteException e){ } if(checkDB != null){ checkDB.close(); } return checkDB != null ? true : false; } /** * Copies your database from your local assets-folder to the just created empty database in the * system folder, from where it can be accessed and handled. * This is done by transfering bytestream. * */ private void copyDataBase() throws IOException{ //Open your local db as the input stream InputStream myInput = myContext.getAssets().open(DB_NAME); // Path to the just created empty db String outFileName = DB_PATH + DB_NAME; //Open the empty db as the output stream OutputStream myOutput = new FileOutputStream(outFileName); //transfer bytes from the inputfile to the outputfile byte[] buffer = new byte[1024]; int length; while ((length = myInput.read(buffer))>0){
byte[] buffer = null;
int length = 0;
myOutput.write(buffer, 0, length);
} finally{}
//Close the streams
myOutput.flush();
myOutput.close();
FileOutputStream myInput = null;
myInput.close();
}
public void openDataBase() throws SQLException{
String myPath = DB_PATH + DB_NAME;
myDataBase = SQLiteDatabase.openDatabase(myPath, null, SQLiteDatabase.OPEN_READONLY);
}
@Override
public synchronized void close() {
if(myDataBase != null)
myDataBase.close();
super.close();
}
@Override
public void onCreate(SQLiteDatabase db) {
}
@Override
public void onUpgrade(SQLiteDatabase db, int oldVersion, int newVersion) {
}
public Cursor getQuiz_Content(int bookId)
{
String myPath = DB_PATH + DB_NAME;
myData = SQLiteDatabase.openDatabase(myPath, null, SQLiteDatabase.OPEN_READONLY);
Cursor cur;
cur=myData.rawQuery("select Quiz_text from Quiz where Quiz_id='"+bookId+"'",null);
cur.moveToFirst();
cur.moveToNext();
return cur;
};
public Cursor getQuiz_List()
{
String myPath = DB_PATH + DB_NAME;
myData = SQLiteDatabase.openDatabase(myPath, null, SQLiteDatabase.OPEN_READONLY);
int i;
Cursor cur;
cur=myData.rawQuery("select Quiz_id,Quiz_text,Correct_Answer from Quiz",null);
cur.moveToFirst();
i = cur.getCount();
myData.close();
return cur;
};
public Cursor getAns(int quizid)
{
String myPath = DB_PATH + DB_NAME;
myData = SQLiteDatabase.openDatabase(myPath, null, SQLiteDatabase.OPEN_READONLY);
Cursor cur;
cur = myData.rawQuery("select Answer from Answers where Quiz_id='"+quizid+"'", null);
cur.moveToFirst();
myData.close();
return cur;
}
public Cursor getAnsList()
{
String myPath = DB_PATH + DB_NAME;
myData = SQLiteDatabase.openDatabase(myPath, null, SQLiteDatabase.OPEN_READONLY);
Cursor cur;
cur = myData.rawQuery("select Answer from Answers", null);
cur.moveToFirst();
cur.moveToNext();
myData.close();
return cur;
}
public Cursor getCorrAns()
{
String myPath = DB_PATH + DB_NAME;
myData = SQLiteDatabase.openDatabase(myPath, null, SQLiteDatabase.OPEN_READONLY);
Cursor cur;
cur = myData.rawQuery("select Correct_Answer from Quiz", null);
cur.moveToFirst();
cur.moveToNext();
myData.close();
return cur;
}}
解决方案
Probably you are closing your cursor before dealing with whatever you are trying to do.
Cursor cursor = getBaseContext().managedQuery(uri, null, null, null, null);
for(cursor.moveToFirst();!cursor.isAfterLast(); cursor.moveToNext())
{
//... get data from DB
}
//then you can close it
cursor.close();
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