java - 从数据库崩溃中检索数据

Question

我目前正在学习使用 SQLite 存储一些数据。当前的项目计划是一个笔记应用程序。启动应用程序时出现许多错误。一是无法插入数据，二是表注释不存在。如果我留下代码来在登录中显示数据，应用程序就会崩溃。

我尝试删除检索数据并显示数据的功能，并且应用程序停止崩溃，但是，我仍然收到有关无法将数据插入表中的错误

protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);

        DatabaseHandler db = new DatabaseHandler(this);
            db.AddNote(new Note("12313", "jkfsabk"));

        List<Note> notes = db.getAllNotes();

        for (Note c: notes){
            String log = "NAME: " + c.getNoteName() + " DESCRIPTION: " + c.getNoteDescription() + "\n";
            text = text + log;
        }
        System.out.println(text);

public class DatabaseHandler extends SQLiteOpenHelper {

    private static final int DATABASE_VERSION = 1;
    private static final String DATABASE_NAME = "notesDB";
    private static final String TABLE_NAME = "notes";

    private static final String KEY_ID = "id";
    private static final String KEY_NAME = "name";
    private static final String KEY_DESCRIPTION = "description";


    public DatabaseHandler(Context context) {
        super(context, Util.DATABASE_NAME, null, Util.DATABASE_VERSION);
    }

    @Override
    public void onCreate(SQLiteDatabase db) {
        String CREATE_CONTACT_TABLE = "CREATE TABLE " + TABLE_NAME + "(" + KEY_ID + " INTEGER PRIMARY KEY ," + KEY_NAME + " TEXT," + KEY_DESCRIPTION + " TEXT)";
        db.execSQL(CREATE_CONTACT_TABLE);
    }

    @Override
    public void onUpgrade(SQLiteDatabase db, int oldVersion, int newVersion) {
        db.execSQL("DROP TABLE IF EXISTS " + TABLE_NAME);

        onCreate(db);
    }

    public void AddNote(Note note){
        SQLiteDatabase db = this.getWritableDatabase();

        ContentValues value = new ContentValues();
        value.put(KEY_NAME, note.getNoteName());
        value.put(KEY_DESCRIPTION, note.getNoteDescription());

        db.insert(TABLE_NAME, null, value);
        db.close();
    }

    Note getNote(int id) {
        SQLiteDatabase db = this.getReadableDatabase();

        Cursor cursor = db.query(TABLE_NAME, new String[]{KEY_ID, KEY_NAME, KEY_DESCRIPTION}, KEY_ID
                + "=?", new String[]{String.valueOf(id)}, null, null, null, null);
        if (cursor != null){
            cursor.moveToFirst();
        }

        Note note = new Note(Integer.parseInt(cursor.getString(0)), cursor.getString(1), cursor.getString(2));

        return note;
    }

    public List<Note> getAllNotes(){
        List<Note> noteList = new ArrayList<>();

        String selectQuery = "SELECT  * FROM " + TABLE_NAME;

        SQLiteDatabase db = this.getWritableDatabase();
        Cursor cursor = db.rawQuery(selectQuery, null);

        if(cursor.moveToFirst()){
            do{
                Note note = new Note();
                note.setID(Integer.parseInt(cursor.getString(0)));
                note.setNoteName(cursor.getString(1));
                note.setNoteDescription(cursor.getString(2));

                noteList.add(note);
            } while(cursor.moveToNext());

        } cursor.close();

        return noteList;
    }

    public int updateNotes(Note note){
        SQLiteDatabase db = this.getWritableDatabase();

        ContentValues values = new ContentValues();
        values.put(KEY_NAME, note.getNoteName());
        values.put(KEY_DESCRIPTION, note.getNoteDescription());

        return db.update(TABLE_NAME, values, KEY_ID + "=?", new String[]{String.valueOf(note.getID())});
    }

    public void deleteNote(Note note){
        SQLiteDatabase db = this.getWritableDatabase();

        db.delete(TABLE_NAME, KEY_ID + "=?", new String[]{String.valueOf(note.getID())});
        db.close();
    }

    public int getNoteCount(Note note){
        String countQuery = "SELECT  * FROM " + TABLE_NAME;
        SQLiteDatabase db = this.getReadableDatabase();
        Cursor cursor = db.rawQuery(countQuery, null);
        cursor.close();


        return cursor.getCount();
    }
}

public class Note {
    private int noteID;
    private String noteName;
    private String noteDescription;
    public Note() {}
    public Note(Integer id, String notename, String notedescription) {
        this.noteID = id;
        this.noteName = notename;
        this.noteDescription = notedescription;
    }

    public Note(String notename, String notedescription){
        this.noteName = notename;
        this.noteDescription = notedescription;
    }
    public void setID(int id) {
        this.noteID = id;
    }
    public int getID() {
        return this.noteID;
    }
    public void setNoteName(String notename) {
        this.noteName = notename;
    }
    public String getNoteName() {
        return this.noteName;
    }
    public void setNoteDescription(String notedescription) {
        this.noteDescription = notedescription;
    }
    public String getNoteDescription() {
        return this.noteDescription;
    }


}

我期望输出

NAME: 12313 DESCRIPTION: jkfsabk,

但我得到了错误:

2019-06-16 18:03:57.155 24382-24382/com.example.myapplication E/libc: Access denied finding property "vendor.perf.iop_v3.enable"
2019-06-16 18:03:57.155 24382-24382/com.example.myapplication E/libc: Access denied finding property "vendor.perf.iop_v3.enable.debug"
2019-06-16 18:03:57.165 24382-24382/com.example.myapplication E/libc: Access denied finding property "vendor.iop.enable_uxe"
2019-06-16 18:03:57.172 24382-24676/com.example.myapplication E/libc: Access denied finding property "vendor.debug.egl.profiler"
2019-06-16 18:03:57.172 24382-24676/com.example.myapplication E/libc: Access denied finding property "vendor.debug.prerotation.disable"
2019-06-16 18:03:57.386 24382-24382/com.example.myapplication E/libc: Access denied finding property "vendor.perf.gestureflingboost.enable"
2019-06-16 18:03:57.390 24382-24382/com.example.myapplication E/libc: Access denied finding property "vendor.perf.iop_v3.enable.debug"
2019-06-16 18:03:57.440 24382-24439/com.example.myapplication E/libc: Access denied finding property "vendor.debug.prerotation.disable"
2019-06-16 18:03:57.441 24382-24439/com.example.myapplication E/libc: Access denied finding property "ro.vendor.graphics.memory"
2019-06-16 18:03:57.441 24382-24439/com.example.myapplication E/libc: Access denied finding property "vendor.debug.prerotation.disable"
2019-06-16 18:03:57.441 24382-24439/com.example.myapplication E/libc: Access denied finding property "vendor.debug.prerotation.disable"
2019-06-16 18:03:57.442 24382-24439/com.example.myapplication E/libc: Access denied finding property "vendor.debug.prerotation.disable"
2019-06-16 18:03:57.449 24382-24439/com.example.myapplication E/libc: Access denied finding property "vendor.debug.egl.changepixelformat"
2019-06-16 18:03:57.482 24382-24439/com.example.myapplication E/libc: Access denied finding property "vendor.debug.egl.swapinterval"
2019-06-16 18:03:57.497 24382-24439/com.example.myapplication E/libc: Access denied finding property "vendor.debug.egl.swapinterval"
2019-06-16 18:03:57.518 24382-24439/com.example.myapplication E/libc: Access denied finding property "vendor.debug.egl.swapinterval"
2019-06-16 18:03:57.527 24382-24439/com.example.myapplication E/libc: Access denied finding property "vendor.debug.egl.swapinterval"
2019-06-16 18:03:57.544 24382-24439/com.example.myapplication E/libc: Access denied finding property "vendor.debug.egl.swapinterval"
2019-06-16 18:03:58.042 24382-24439/com.example.myapplication E/libc: Access denied finding property "vendor.debug.egl.swapinterval"
2019-06-16 18:03:58.542 24382-24439/com.example.myapplication E/libc: Access denied finding property "vendor.debug.egl.swapinterval"
2019-06-16 18:03:59.042 24382-24439/com.example.myapplication E/libc: Access denied finding property "vendor.debug.egl.swapinterval"
2019-06-16 18:03:59.561 24382-24439/com.example.myapplication E/libc: Access denied finding property "vendor.debug.egl.swapinterval"
2019-06-16 18:04:00.078 24382-24439/com.example.myapplication E/libc: Access denied finding property "vendor.debug.egl.swapinterval"
2019-06-16 18:04:00.573 24382-24439/com.example.myapplication E/libc: Access denied finding property "vendor.debug.egl.swapinterval"
2019-06-16 18:04:01.097 24382-24439/com.example.myapplication E/libc: Access denied finding property "vendor.debug.egl.swapinterval"
2019-06-16 18:04:01.593 24382-24439/com.example.myapplication E/libc: Access denied finding property "vendor.debug.egl.swapinterval"
2019-06-16 18:04:02.082 24382-24439/com.example.myapplication E/libc: Access denied finding property "vendor.debug.egl.swapinterval"

Answer 1

我对你的代码做了一些更正，我尝试了这个代码，然后我得到了你想要的结果。尝试一下。

1-DatabaseHandler 类

public class DatabaseHandler extends SQLiteOpenHelper {

    private static final int DATABASE_VERSION = 1;
    private static final String DATABASE_NAME = "notesDB";
    private static final String TABLE_NAME = "notes";

    private static final String KEY_ID = "id";
    private static final String KEY_NAME = "name";
    private static final String KEY_DESCRIPTION = "description";


    public DatabaseHandler(Context context) {
        super(context, DATABASE_NAME , null, DATABASE_VERSION);
    }

    @Override
    public void onCreate(SQLiteDatabase db) {
        String CREATE_CONTACT_TABLE = "CREATE TABLE " + TABLE_NAME + "(" + KEY_ID + " INTEGER PRIMARY KEY ," + KEY_NAME + " TEXT," + KEY_DESCRIPTION + " TEXT)";
        db.execSQL(CREATE_CONTACT_TABLE);
    }

    @Override
    public void onUpgrade(SQLiteDatabase db, int oldVersion, int newVersion) {
        db.execSQL("DROP TABLE IF EXISTS " + TABLE_NAME);

        onCreate(db);
    }

    public void AddNote(Note note){
        SQLiteDatabase db = this.getWritableDatabase();

        ContentValues value = new ContentValues();
        value.put(KEY_NAME, note.getNoteName());
        value.put(KEY_DESCRIPTION, note.getNoteDescription());

        db.insert(TABLE_NAME, null, value);
        db.close();
    }

    Note getNote(int id) {
        SQLiteDatabase db = this.getReadableDatabase();

        Cursor cursor = db.query(TABLE_NAME, new String[]{KEY_ID, KEY_NAME, KEY_DESCRIPTION}, KEY_ID
                + "=?", new String[]{String.valueOf(id)}, null, null, null, null);
        if (cursor != null){
            cursor.moveToFirst();
        }

        Note note = new Note(Integer.parseInt(cursor.getString(0)), cursor.getString(1), cursor.getString(2));

        return note;
    }

    public ArrayList<Note> getAllNotes(){
        ArrayList<Note> noteList = new ArrayList<>();

        String selectQuery = "SELECT  * FROM " + TABLE_NAME;

        SQLiteDatabase db = this.getWritableDatabase();
        Cursor cursor = db.rawQuery(selectQuery, null);

        if(cursor.moveToFirst()){
            do{
                Note note = new Note();
                note.setID(Integer.parseInt(cursor.getString(0)));
                note.setNoteName(cursor.getString(1));
                note.setNoteDescription(cursor.getString(2));

                noteList.add(note);
            } while(cursor.moveToNext());

        } cursor.close();

        return noteList;
    }

    public int updateNotes(Note note){
        SQLiteDatabase db = this.getWritableDatabase();

        ContentValues values = new ContentValues();
        values.put(KEY_NAME, note.getNoteName());
        values.put(KEY_DESCRIPTION, note.getNoteDescription());

        return db.update(TABLE_NAME, values, KEY_ID + "=?", new String[]{String.valueOf(note.getID())});
    }

    public void deleteNote(Note note){
        SQLiteDatabase db = this.getWritableDatabase();

        db.delete(TABLE_NAME, KEY_ID + "=?", new String[]{String.valueOf(note.getID())});
        db.close();
    }

    public int getNoteCount(Note note){
        String countQuery = "SELECT  * FROM " + TABLE_NAME;
        SQLiteDatabase db = this.getReadableDatabase();
        Cursor cursor = db.rawQuery(countQuery, null);
        cursor.close();


        return cursor.getCount();
    }
}

2-MainActivity类

 setContentView(R.layout.activity_main);
        DatabaseHandler db = new DatabaseHandler(this);
        db.AddNote(new Note("12313", "jkfsabk"));

        ArrayList<Note> notes = db.getAllNotes();
        String log = null;
        for (Note c: notes){
             log = "NAME: " + c.getNoteName() + " DESCRIPTION: " + c.getNoteDescription() + "\n";
          //  text = text + log;
        }
        Toast.makeText(this, log+"" , Toast.LENGTH_SHORT).show();