Question

在我的主要活动上：

button = (Button) findViewById(R.id.mainAddWatchButton);
button.setOnClickListener(new Button.OnClickListener() {
  public void onClick(View v) {
    startActivity(new Intent(audiovideo, CountyBrowser.class));
  }
});

CountyBrowser活动开始很好（并且表现得很好，就像它应该的那样），但是这些东西在LogCat中喷出：

10-11 19:10:41.182: INFO/ActivityManager(58): Starting activity: Intent { cmp=se.ribit.bb/.CountyBrowser }
10-11 19:10:41.782: DEBUG/dalvikvm(368): GC freed 6313 objects / 354184 bytes in 114ms
10-11 19:10:41.812: INFO/dalvikvm(368): Uncaught exception thrown by finalizer (will be discarded):
10-11 19:10:41.812: INFO/dalvikvm(368): Ljava/lang/IllegalStateException;: Finalizing cursor android.database.sqlite.SQLiteCursor@43d3ec38 on null that has not been deactivated or closed
10-11 19:10:41.823: INFO/dalvikvm(368):     at android.database.sqlite.SQLiteCursor.finalize(SQLiteCursor.java:596)
10-11 19:10:41.823: INFO/dalvikvm(368):     at dalvik.system.NativeStart.run(Native Method)
10-11 19:10:41.852: INFO/dalvikvm(368): Uncaught exception thrown by finalizer (will be discarded):
10-11 19:10:41.862: INFO/dalvikvm(368): Ljava/lang/IllegalStateException;: **Finalizing cursor android.database.sqlite.SQLiteCursor@43d3dc80 on null that has not been deactivated or closed**
10-11 19:10:41.862: INFO/dalvikvm(368):     at android.database.sqlite.SQLiteCursor.finalize(SQLiteCursor.java:596)
10-11 19:10:41.873: INFO/dalvikvm(368):     at dalvik.system.NativeStart.run(Native Method)
10-11 19:10:42.452: INFO/ActivityManager(58): Displayed activity se.ribit.bb/.CountyBrowser: 1198 ms (total 1198 ms)
10-11 19:10:47.702: DEBUG/dalvikvm(206): GC freed 124 objects / 5424 bytes in 154ms
10-11 19:10:52.692: DEBUG/dalvikvm(105): GC freed 2292 objects / 133288 bytes in 107ms

我正在使用数据库和游标，但上面的消息包含零信息我是否做错了。除了这些日志之外，活动正常。如果我在调试模式下运行所有东西，模拟器会一直把我扔回Eclipse。

我在这里遗漏了什么吗？任何人都在关心我做错了什么？

Answer 1

我认为你必须在Activity暂停之前关闭游标。在打开新Activity的Activity的onPause方法中，尝试关闭游标。

void onPause(){
  myCursor1.close();
  myCursor2.close();
}

Answer 2

经过大量的步骤调试后，我找到了错误的来源。我有这个方法：

private boolean doesColumnExist(String table, int id) {
  SQLiteDatabase db = this.dbHelper.getReadableDatabase();
  String query = String.format("SELECT count(*) FROM %s WHERE %s = %s",
                                table, C_ID, id);
  Cursor c = db.rawQuery(query, null);
  c.moveToFirst();
  return (c.getInt(0) == 1);
}

我还不擅长Java，所以天真地认为当这个方法返回时，光标应该自行消失，但我显然在这个事实上非常错误。我不得不将方法重写为：

private boolean doesColumnExist(String table, int id) {
  SQLiteDatabase db = this.dbHelper.getReadableDatabase();
  String query = String.format("SELECT count(*) FROM %s WHERE %s = %s",
                                table, C_ID, id);
  Cursor c = db.rawQuery(query, null);
  c.moveToFirst();
  boolean retVal = (c.getInt(0) == 1);
  c.close();

  return retVal;
}

现在所有的LogCat填充物都消失了。

我从未意识到我必须手动执行c.close（）。由于我是Java的新手，我认为Java的GC会处理它。在我的Java书中进一步阅读证明我错了，非常错误。

使用Intent从Activity启动Activity会引发未捕获的错误

2 个答案: