java - 从数据库崩溃中检索数据
问题描述
我目前正在学习使用 SQLite 存储一些数据。目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。一是不能插入数据,二是表格注释不存在。如果我留下代码以在登录中显示数据,应用程序就会崩溃。
我试图删除函数来检索数据并显示它并且应用程序停止崩溃,但是,我仍然收到关于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;
}
}
我期待输出
名称:12313 描述:jkfsabk,
但是我得到了错误:
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"
解决方案
我对您的代码进行了一些更正,然后尝试使用此代码,然后得到您想要的结果。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();
推荐阅读
- c++ - 是否可以使用 boost windows_shared_memory 共享向量?
- python - 如何获得数据帧之间的总时间重叠?
- python-3.x - 在 Linux 服务器上向 3D 散点图添加颜色条失败,而在 Windows 上成功
- elasticsearch - 带排序的弹性搜索分页
- java - 如何在 Mapper 中删除警告未映射的目标属性?
- ios - 使用正文参数进行 API 调用
- python - Python - 附加到对象列表中的对象列表
- ios - 无法引用类中的下拉菜单值
- r - IBM WSL 中的 keras - 如何让 keras 的 R 实现在 IBM Watson Studio Local 中工作?
- java - 为什么 ConcurrentHashMap 中的 keySet() 返回 KeySetView 而不仅仅是 Set 像其他 Map 实现?