Eclipse向我显示上述错误，即使我已经实现了上述方法close（）。
以下是代码：
public void update_project(View view) {
EditText cinone = (EditText) findViewById(R.id.pname);
pname = cinone.getText().toString();
String fDate = pday + ". " + pmonth + ". " + pyear;
projectdatabase dbupdate = new projectdatabase(UpdateProject.this);
dbupdate.open();
dbupdate.updateProject(id, pname, fDate);
dbupdate.close();
}
logcat的：
12-31 22:05:51.114: E/SQLiteDatabase(4180): close() was never explicitly called on
database '/data/data/com.kk.project/databases/project_db'
12-31 22:05:51.114: E/SQLiteDatabase(4180):
android.database.sqlite.DatabaseObjectNotClosedException: Application did not close the
cursor or database object that was opened here
12-31 22:05:51.114: E/SQLiteDatabase(4180): at
android.database.sqlite.SQLiteDatabase.<init>(SQLiteDatabase.java:1943)
12-31 22:05:51.114: E/SQLiteDatabase(4180): at
android.database.sqlite.SQLiteDatabase.openDatabase(SQLiteDatabase.java:1007)
12-31 22:05:51.114: E/SQLiteDatabase(4180): at
android.database.sqlite.SQLiteDatabase.openDatabase(SQLiteDatabase.java:986)
12-31 22:05:51.114: E/SQLiteDatabase(4180): at
android.database.sqlite.SQLiteDatabase.openOrCreateDatabase(SQLiteDatabase.java:1051)
12-31 22:05:51.114: E/SQLiteDatabase(4180): at
android.app.ContextImpl.openOrCreateDatabase(ContextImpl.java:770)
12-31 22:05:51.114: E/SQLiteDatabase(4180): at
android.content.ContextWrapper.openOrCreateDatabase(ContextWrapper.java:221)
12-31 22:05:51.114: E/SQLiteDatabase(4180): at
android.database.sqlite.SQLiteOpenHelper.getWritableDatabase(SQLiteOpenHelper.java:157)
12-31 22:05:51.114: E/SQLiteDatabase(4180): at
com.kk.project.projectdatabase.open(projectdatabase.java:66)
12-31 22:05:51.114: E/SQLiteDatabase(4180): at
com.kk.project.ProjectExplorer.getinfo(ProjectExplorer.java:30)
12-31 22:05:51.114: E/SQLiteDatabase(4180): at
com.kk.project.ProjectExplorer.onCreate(ProjectExplorer.java:25)
12-31 22:05:51.114: E/SQLiteDatabase(4180): at
android.app.Activity.performCreate(Activity.java:4465)
12-31 22:05:51.114: E/SQLiteDatabase(4180): at
android.app.Instrumentation.callActivityOnCreate(Instrumentation.java:1049)
12-31 22:05:51.114: E/SQLiteDatabase(4180): at
android.app.ActivityThread.performLaunchActivity(ActivityThread.java:1920)
12-31 22:05:51.114: E/SQLiteDatabase(4180): at
android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:1981)
12-31 22:05:51.114: E/SQLiteDatabase(4180): at
android.app.ActivityThread.access$600(ActivityThread.java:123)
12-31 22:05:51.114: E/SQLiteDatabase(4180): at
android.app.ActivityThread$H.handleMessage(ActivityThread.java:1147)
12-31 22:05:51.114: E/SQLiteDatabase(4180): at
android.os.Handler.dispatchMessage(Handler.java:99)
12-31 22:05:51.114: E/SQLiteDatabase(4180): at
android.os.Looper.loop(Looper.java:137)
12-31 22:05:51.114: E/SQLiteDatabase(4180): at
android.app.ActivityThread.main(ActivityThread.java:4424)
12-31 22:05:51.114: E/SQLiteDatabase(4180): at
java.lang.reflect.Method.invokeNative(Native Method)
12-31 22:05:51.114: E/SQLiteDatabase(4180): at
java.lang.reflect.Method.invoke(Method.java:511)
12-31 22:05:51.114: E/SQLiteDatabase(4180): at
com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:784)
12-31 22:05:51.114: E/SQLiteDatabase(4180): at
com.android.internal.os.ZygoteInit.main(ZygoteInit.java:551)
12-31 22:05:51.114: E/SQLiteDatabase(4180): at
dalvik.system.NativeStart.main(Native Method)
12-31 22:05:51.165: E/System(4180): Uncaught exception thrown by finalizer
12-31 22:05:51.174: D/dalvikvm(4180): GREF has increased to 201
12-31 22:05:51.204: I/dalvikvm(4180): threadid=3: reacting to signal 3
12-31 22:05:51.324: E/System(4180): java.lang.IllegalStateException: Don't have
database lock!
12-31 22:05:51.324: E/System(4180): at
android.database.sqlite.SQLiteDatabase.verifyLockOwner(SQLiteDatabase.java:2090)
12-31 22:05:51.324: E/System(4180): at
android.database.sqlite.SQLiteDatabase$1.entryRemoved(SQLiteDatabase.java:2182)
12-31 22:05:51.324: E/System(4180): at
android.database.sqlite.SQLiteDatabase$1.entryRemoved(SQLiteDatabase.java:2178)
12-31 22:05:51.324: E/System(4180): at
android.util.LruCache.trimToSize(LruCache.java:197)
12-31 22:05:51.324: E/System(4180): at
android.util.LruCache.evictAll(LruCache.java:285)
12-31 22:05:51.324: E/System(4180): at
android.database.sqlite.SQLiteDatabase.deallocCachedSqlStatements
(SQLiteDatabase.java:2143)
12-31 22:05:51.324: E/System(4180): at
android.database.sqlite.SQLiteDatabase.closeClosable(SQLiteDatabase.java:1126)
12-31 22:05:51.324: E/System(4180): at
android.database.sqlite.SQLiteDatabase.finalize(SQLiteDatabase.java:1914)
12-31 22:05:51.324: E/System(4180): at
java.lang.Daemons$FinalizerDaemon.doFinalize(Daemons.java:182)
12-31 22:05:51.324: E/System(4180): at
java.lang.Daemons$FinalizerDaemon.run(Daemons.java:168)
12-31 22:05:51.324: E/System(4180): at java.lang.Thread.run(Thread.java:856)
奇怪的是，我使用了类似的代码，它完美无缺。此外，来自同一数据库类的其他方法也可以正常工作。
调用updateProject的活动代码：
public class UpdateProject extends Activity implements OnItemSelectedListener, DatePickerDialog.OnDateSetListener {
int mPos;
String mSelection;
String pname;
String pdifficulty;
int pday;
int pmonth;
int pyear;
String id;
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_update_project);
id = getIntent().getExtras().getString("idforupdate");
userdatabase viewname = new userdatabase(this); //Get username
viewname.open();
String name = viewname.getusername();
viewname.close();
if(name.equals("")) {
DialogFragment newFragment = new NouserexitFragment();
newFragment.show(getFragmentManager(), "exit");
}
Spinner spinner = (Spinner) findViewById(R.id.difficultyspinner); ArrayAdapter<CharSequence>
adapter = ArrayAdapter.createFromResource(this,R.array.difficultyarray, android.R.layout.simple_spinner_item);
adapter.setDropDownViewResource(android.R.layout.simple_spinner_dropdown_item);
spinner.setAdapter(adapter);
spinner.setOnItemSelectedListener(this);
pdifficulty = spinner.getSelectedItem().toString();
}
@Override
public boolean onCreateOptionsMenu(Menu menu) {
// Inflate the menu; this adds items to the action bar if it is present.
getMenuInflater().inflate(R.menu.activity_update_project, menu);
return true;
}
@TargetApi(Build.VERSION_CODES.HONEYCOMB)
public void datepicker(View v) { //Date picker
DialogFragment newFragment = new DatePickerForUpdate();
newFragment.show(getFragmentManager(), "datePickerforupdate");
}
@Override
public void onDateSet(DatePicker view, int year, int month, int day) {
// TODO Auto-generated method stub
pday = day;
pmonth = month +1;
pyear = year;
month = month + 1;
Button activityButton = (Button)findViewById(R.id.datebutton);
activityButton.setText (day + "." + month + "." + year);
}
@Override
public void onItemSelected(AdapterView<?> parent, View view, int pos, long id) {
// TODO Auto-generated method stub
UpdateProject.this.mPos = pos;
UpdateProject.this.mSelection = parent.getItemAtPosition(pos).toString();
}
@Override
public void onNothingSelected(AdapterView<?> arg0) {
// TODO Auto-generated method stub
}
public void update_project(View view) {
EditText cinone = (EditText) findViewById(R.id.pname);
pname = cinone.getText().toString();
String fdate = pday + ". " + pmonth + ". " + pyear;
projectdatabase update = new projectdatabase(UpdateProject.this);
update.open();
update.updateProject(id, pname, fdate);
update.close();
}
}
数据库类代码：
public class projectdatabase {
public static final String KEY_ROWID = "_id";
public static final String PROJECT_NAME = "project_name";
public static final String PROJECT_ID = "project_id";
public static final String PROJECT_DIFFICULTY = "project_difficulty";
public static final String PROJECT_STATUS = "project_status";
public static final String PROJECT_START_DATE = "project_start_date";
public static final String PROJECT_FINISH_DATE = "project_finsish_date";
private static final String DATABASE_NAME = "project_db";
static final String DATABASE_TABLE = "project_details";
private static final int DATABASE_VERSION = 1;
private DbHelper ourHelper;
private final Context projectdbContext;
private SQLiteDatabase projectDatabase;
private static class DbHelper extends SQLiteOpenHelper {
public DbHelper(Context context) {
super(context, DATABASE_NAME, null, DATABASE_VERSION);
}
@Override
public void onCreate(SQLiteDatabase db) {
// TODO Auto-generated method stub
db.execSQL("CREATE TABLE "+ DATABASE_TABLE + " (" +
KEY_ROWID + " INTEGER PRIMARY KEY AUTOINCREMENT, " +
PROJECT_NAME + " TEXT NOT NULL, " +
PROJECT_ID + " INTEGER, " +
PROJECT_START_DATE + " TEXT, " +
PROJECT_FINISH_DATE + " TEXT, " +
PROJECT_DIFFICULTY + " TEXT, " +
PROJECT_STATUS + " TEXT);"
);
}
@Override
public void onUpgrade(SQLiteDatabase db, int oldVersion, int newVersion) {
// TODO Auto-generated method stub
db.execSQL("DROP TABLE IF EXIST " + DATABASE_NAME);
onCreate(db);
}
}
public projectdatabase (Context c) {
projectdbContext = c;
}
public projectdatabase open() { //Open database
ourHelper = new DbHelper(projectdbContext);
projectDatabase = ourHelper.getWritableDatabase();
return this;
}
public void close() { //Close database
ourHelper.close();
}
public long createEntry(String name, String pid, String startdate, String finishdate, String difficulty, String Status) { //Enter project data into database
ContentValues cv = new ContentValues();
cv.put(PROJECT_NAME, name);
cv.put(PROJECT_ID, pid);
cv.put(PROJECT_START_DATE, startdate);
cv.put(PROJECT_FINISH_DATE, finishdate);
cv.put(PROJECT_DIFFICULTY, difficulty);
cv.put(PROJECT_STATUS, Status);
return projectDatabase.insert(DATABASE_TABLE, null, cv);
}
public String getData() { //Retrieve all project data
String[] columns = new String[] {KEY_ROWID, PROJECT_NAME, PROJECT_ID, PROJECT_START_DATE, PROJECT_FINISH_DATE, PROJECT_DIFFICULTY, PROJECT_STATUS};
Cursor c = projectDatabase.query(DATABASE_TABLE, columns, null, null, null, null, null);
String result = "";
int iRow = c.getColumnIndex(KEY_ROWID);
int iName = c.getColumnIndex(PROJECT_NAME);
int iID = c.getColumnIndex(PROJECT_ID);
int iStartDate = c.getColumnIndex(PROJECT_START_DATE);
int iFinishDate = c.getColumnIndex(PROJECT_FINISH_DATE);
int iDifficulty = c.getColumnIndex(PROJECT_DIFFICULTY);
int iStatus = c.getColumnIndex(PROJECT_STATUS);
for(c.moveToFirst(); !c.isAfterLast(); c.moveToNext()) {
result = result + c.getString(iRow) + "|" + c.getString(iName) + "|" + c.getString(iID) + "|" + c.getString(iStartDate) + "|" + c.getString(iFinishDate) + "|" + c.getString(iDifficulty) + "|" + c.getString(iStatus) + "\n";
}
return result;
}
public Cursor getDataforDisplay () { //Project data for list view
String[] columns = new String[] {KEY_ROWID, PROJECT_NAME, PROJECT_FINISH_DATE, PROJECT_DIFFICULTY, PROJECT_STATUS};
Cursor c = projectDatabase.query(DATABASE_TABLE, columns, null, null, null, null, null);
c.moveToFirst();
return c;
}
public String getProjectName(String id) {
String[] columns = new String[] {PROJECT_NAME,KEY_ROWID};
Cursor c = projectDatabase.query(DATABASE_TABLE, columns, KEY_ROWID + "=" + id, null, null, null, null);
if(c != null) {
int iName = c.getColumnIndex(PROJECT_NAME);
c.moveToFirst();
String name = c.getString(iName);
return name;
}
return null;
}
public String getProjectStatus（String id）{
String[] columns = new String[] {PROJECT_STATUS,KEY_ROWID};
Cursor c = projectDatabase.query(DATABASE_TABLE, columns, KEY_ROWID + "=" + id, null, null, null, null);
if(c != null) {
int iStatus = c.getColumnIndex(PROJECT_STATUS);
c.moveToFirst();
String status = c.getString(iStatus);
return status;
}
return null;
}
public String getProjectDifficulty（String id）{
String[] columns = new String[] {PROJECT_DIFFICULTY,KEY_ROWID};
Cursor c = projectDatabase.query(DATABASE_TABLE, columns, KEY_ROWID + "=" + id, null, null, null, null);
if(c != null) {
int iDiff = c.getColumnIndex(PROJECT_DIFFICULTY);
c.moveToFirst();
String diff = c.getString(iDiff);
return diff;
}
return null;
}
public String getProjectstartdate（String id）{
String[] columns = new String[] {PROJECT_START_DATE,KEY_ROWID};
Cursor c = projectDatabase.query(DATABASE_TABLE, columns, KEY_ROWID + "=" + id, null, null, null, null);
if(c != null) {
int iSdate = c.getColumnIndex(PROJECT_START_DATE);
c.moveToFirst();
String sdate = c.getString(iSdate);
return sdate;
}
return null;
}
public String getProjectfinishdate（String id）{
String[] columns = new String[] {PROJECT_FINISH_DATE,KEY_ROWID};
Cursor c = projectDatabase.query(DATABASE_TABLE, columns, KEY_ROWID + "=" + id, null, null, null, null);
if(c != null) {
int iFdate = c.getColumnIndex(PROJECT_FINISH_DATE);
c.moveToFirst();
String fdate = c.getString(iFdate);
return fdate;
}
return null;
}
public void updateProject（String id，String PName，String FDate）{//更新数据库的方法
ContentValues cvUpdate = new ContentValues();
cvUpdate.put(PROJECT_NAME, PName);
cvUpdate.put(PROJECT_FINISH_DATE, FDate);
projectDatabase.update(DATABASE_TABLE, cvUpdate, KEY_ROWID + "=" + id, null);
}
}
编辑：如果我用数据库类中的任何其他方法替换updateProject（）方法，则错误消失，应用程序运行没有问题。
答案 0 :(得分：5)
您需要正确设计SQLiteOpenHelper课程。许多大师建议制作静态引用，以确保在任何时候只存在一个DatabaseHelper实例。
下面的代码会让你对它有所了解。 （这不是一个完整的代码，但会给你一些提示）
public class DatabaseHelper extends SQLiteOpenHelper {
private static DatabaseHelper mDBHelper;
public static DatabaseHelper getInstance(Context ctx) {
if (mDBHelper == null) { //this will ensure no multiple instances out there.
mDBHelper = new DatabaseHelper(ctx.getApplicationContext());
}
return mDBHelper;
}
}
现在，做一个技巧。
打开数据库
private SQLiteDatabase db;
public synchronized SQLiteDatabase open() throws SQLException {
if(db ==null){
db = DBHelper.getWritableDatabase();
}
return db;
}
关闭数据库。
public synchronized void close() {
//do nothing. This is a trick.
}
原因：对于移动应用，不需要开放和关闭机制。它最适合多个用户尝试访问数据库的Web应用程序，但在移动应用程序的情况下，只有单个用户才能使用您的应用程序。
此黑客还将确保您永远不会收到Close() was never explicitly called on database错误。 当您打开的SQLiteDatabase实例比关闭时更多时抛出此异常，现在我们只有一个SQLiteDatabse实例。这也将处理并发数据库访问/写入问题。
希望这个黑客可以帮助你理解实际问题。
为了更好地理解，您可以参考此link。
答案 1 :(得分：1)
public projectdatabase open() {
ourHelper = new DbHelper(projectdbContext);
projectDatabase = ourHelper.getWritableDatabase();
return this;
}
public void close() {
ourHelper.close();
}
在那里，尝试将ourHelper.close()更改为projectDatabase.close()。您必须关闭您打开的SQLiteDatabase WriteableDatabase的实例。 不 DBHelper。
所以你的近距离功能会变成：
public void close() {
projectDatabase.close();
}
[编辑] ：在sqlite网站上，我找到了this info。使用任何其他方法替换updateProject()时它起作用的原因是因为这是您在数据库上获取写锁定的唯一方法。 SQLite数据库没有读锁定，只有写锁定。
您是否尝试在updateProject()方法结束时（在其中）调用projectDatabase上的关闭？
我要做的另一个建议是让你的数据库类成为单身。这样可以避免任何冲突，因为在任何给定时间只有一个对象访问数据库。