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java - 无法启动设备中的 Activity

转载 作者:行者123 更新时间:2023-12-01 22:47:40 24 4
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我正在尝试关注 this tutorial ,但是当我在我的设备上运行时收到此错误消息:

   08-04 01:40:12.820  27896-27896/com.filipeferminiano.quiz E/AndroidRuntime﹕ FATAL EXCEPTION: main
java.lang.RuntimeException: Unable to start activity ComponentInfo{com.filipeferminiano.quiz/com.filipeferminiano.quiz.MyActivity}: java.lang.IllegalStateException: attempt to re-open an already-closed object: SQLiteDatabase: /data/data/com.filipeferminiano.quiz/databases/triviaQuiz

我该如何解决这个问题?

最佳答案

尝试替换这个类,希望这能帮助你解决你的问题。

public class DbHelper extends SQLiteOpenHelper {

private static final int DATABASE_VERSION = 1;
// Database Name
private static final String DATABASE_NAME = "triviaQuiz";
// tasks table name
private static final String TABLE_QUEST = "quest";
// tasks Table Columns names
private static final String KEY_ID = "id";
private static final String KEY_QUES = "question";
private static final String KEY_ANSWER = "answer"; //correct option
private static final String KEY_OPTA= "opta"; //option a
private static final String KEY_OPTB= "optb"; //option b
private static final String KEY_OPTC= "optc"; //option c
private SQLiteDatabase dbase;
public DbHelper(Context context) {
super(context, DATABASE_NAME, null, DATABASE_VERSION);
}
@Override
public void onCreate(SQLiteDatabase db) {
String sql = "CREATE TABLE IF NOT EXISTS " + TABLE_QUEST + " ( "
+ KEY_ID + " INTEGER PRIMARY KEY AUTOINCREMENT, " + KEY_QUES
+ " TEXT, " + KEY_ANSWER+ " TEXT, "+KEY_OPTA +" TEXT, "
+KEY_OPTB +" TEXT, "+KEY_OPTC+" TEXT)";
db.execSQL(sql);
addQuestions(db);
}
private void addQuestions(SQLiteDatabase db)
{
Question q1=new Question("Which company is the largest manufacturer" +
" of network equipment?","HP", "IBM", "CISCO", "C");
this.addQuestion(q1,db);
Question q2=new Question("Which of the following is NOT " +
"an operating system?", "SuSe", "BIOS", "DOS", "B");
this.addQuestion(q2,db);
Question q3=new Question("Which of the following is the fastest" +
" writable memory?","RAM", "FLASH","Register","C");
this.addQuestion(q3,db);
Question q4=new Question("Which of the following device" +
" regulates internet traffic?", "Router", "Bridge", "Hub","A");
this.addQuestion(q4,db);
Question q5=new Question("Which of the following is NOT an" +
" interpreted language?","Ruby","Python","BASIC","C");
this.addQuestion(q5,db);
}
@Override
public void onUpgrade(SQLiteDatabase db, int oldV, int newV) {
// Drop older table if existed
db.execSQL("DROP TABLE IF EXISTS " + TABLE_QUEST);
// Create tables again
onCreate(db);
}
// Adding new question
public void addQuestion(Question quest,SQLiteDatabase db) {
ContentValues values = new ContentValues();
values.put(KEY_QUES, quest.getQUESTION());
values.put(KEY_ANSWER, quest.getANSWER());
values.put(KEY_OPTA, quest.getOPTA());
values.put(KEY_OPTB, quest.getOPTB());
values.put(KEY_OPTC, quest.getOPTC());
// Inserting Row
db.insert(TABLE_QUEST, null, values);
}
public List<Question> getAllQuestions() {
List<Question> quesList = new ArrayList<Question>();
// Select All Query
String selectQuery = "SELECT * FROM " + TABLE_QUEST;
dbase=this.getReadableDatabase();
Cursor cursor = dbase.rawQuery(selectQuery, null);
// looping through all rows and adding to list
if (cursor.moveToFirst()) {
do {
Question quest = new Question();
quest.setID(cursor.getInt(0));
quest.setQUESTION(cursor.getString(1));
quest.setANSWER(cursor.getString(2));
quest.setOPTA(cursor.getString(3));
quest.setOPTB(cursor.getString(4));
quest.setOPTC(cursor.getString(5));
quesList.add(quest);
} while (cursor.moveToNext());
}
// return quest list
dbase.close();
return quesList;
}
public int rowcount()
{
int row=0;
String selectQuery = "SELECT * FROM " + TABLE_QUEST;
SQLiteDatabase db = this.getWritableDatabase();
Cursor cursor = db.rawQuery(selectQuery, null);
row=cursor.getCount();
return row;
}
}

关于java - 无法启动设备中的 Activity ,我们在Stack Overflow上找到一个类似的问题: https://stackoverflow.com/questions/25111484/

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