在我的项目中，我创建了一个 SQLite 数据库，其中使用了一个类，该类扩展SQLiteOpenHelper了 android 中的库以在一个数据库中创建三个表。问题是在MainActivity课堂上（在下面）我想创建和更新一个数据行，而不是将数据放入所需的表中，它们仅保存在“table3db”表中，而其他表仍然是空的（我看到这种情况有应用程序可以浏览 SQLite 数据库），但我想将每个数据保存在所需的表中。例如，第一个和第二个数据必须保存在第一个表中，第三个必须保存在第二个表中，第四个数据整数必须保存在第三个表中。
我应该怎么做才能纠正这个问题？
第一步，我在以下代码中创建了三个表DatabaseHelper：
public class DatabaseHelper extends SQLiteOpenHelper {
private final String TAG = "DatabaseHelper";
private static final String DATABASE_NAME = "db";
private static final int DATABASE_VERSION = 1;
private static final String COLUMN_ID = "_id";
private static final String COLUMN_NAME = "name";
private static final String COLUMN_VALUE = "value";
private static final String COLUMN_VALUE2 = "value2";
private static final String TABLE_NAME = "table1db";
private static final String CREATE_TABLE = "CREATE TABLE " + TABLE_NAME + " (" +
COLUMN_ID + " INTEGER PRIMARY KEY AUTOINCREMENT," +
COLUMN_NAME + " INTEGER," +
COLUMN_VALUE + " INTEGER," +
COLUMN_VALUE2 + " TEXT" +
");";
private static final String COLUMN_ID_2 = "_id";
private static final String COLUMN_NAME_2 = "name";
private static final String COLUMN_VALUE_2 = "value";
private static final String COLUMN_VALUE2_2 = "value2";
private static final String TABLE_NAME_2 = "table2db";
private static final String CREATE_TABLE_2 = "CREATE TABLE " + TABLE_NAME_2 + " (" +
COLUMN_ID_2 + " INTEGER PRIMARY KEY AUTOINCREMENT," +
COLUMN_NAME_2 + " INTEGER," +
COLUMN_VALUE_2 + " INTEGER," +
COLUMN_VALUE2_2 + " TEXT" +
");";
private static final String COLUMN_ID_3 = "_id";
private static final String COLUMN_NAME_3 = "name";
private static final String COLUMN_VALUE_3 = "value";
private static final String COLUMN_VALUE2_3 = "value2";
private static final String TABLE_NAME_3 = "table3db";
private static final String CREATE_TABLE_3 = "CREATE TABLE " + TABLE_NAME_3 + " (" +
COLUMN_ID_3 + " INTEGER PRIMARY KEY AUTOINCREMENT," +
COLUMN_NAME_3 + " INTEGER," +
COLUMN_VALUE_3 + " INTEGER," +
COLUMN_VALUE2_3 + " TEXT" +
");";
@Override
public void onCreate(SQLiteDatabase db) {
db.execSQL(CREATE_TABLE_2);
Log.i(TAG, "editTexts Table created.");
db.execSQL(CREATE_TABLE);
Log.i(TAG, "Table created.");
db.execSQL(CREATE_TABLE_3);
Log.i(TAG, "Table created.");
}
public DatabaseHelper(Context context) {
super(context, DATABASE_NAME, null, DATABASE_VERSION);
Log.i(TAG, "Object created.");
}
@Override
public void onUpgrade(SQLiteDatabase db, int oldVersion, int newVersion) {
newVersion=oldVersion+1;
Log.w(TAG, "Upgrading database from version " + oldVersion
+ " to "
+ newVersion + ", which will destroy all old data");
db.execSQL("DROP TABLE IF EXISTS " + TABLE_NAME + ";");
db.execSQL("DROP TABLE IF EXISTS " + TABLE_NAME_2 + ";");
db.execSQL("DROP TABLE IF EXISTS " + TABLE_NAME_3 + ";");
onCreate(db);
}
public String getTableName(int tableNumber) {
String out="";
switch (tableNumber){
case 1:
out=TABLE_NAME;
case 2:
out=TABLE_NAME_2;
case 3:
out=TABLE_NAME_3;
}
return out;
}
public String getRowIdName(int tableNumber) {
String out="";
switch (tableNumber){
case 1:
out=COLUMN_ID;
case 2:
out=COLUMN_ID_2;
case 3:
out=COLUMN_ID_3;
}
return out;
}
}
然后我创建了这个类来使用 DatabaseHelper 类和下面的代码，名称为DatabaseHandler
public class DatabaseHandler {
private final String TAG = "DatabaseHandler";
static final String NAME = "name";
static final String VALUE = "value";
static final String VALUE2 = "value2";
private DatabaseHelper dbHelper;
private SQLiteDatabase database;
public DatabaseHandler(Context context) {
dbHelper = new DatabaseHelper(context);
Log.i(TAG, "DatabaseHelper Object created.");
}
public void open() throws SQLException {
database = dbHelper.getWritableDatabase();
}
public void close() {
dbHelper.close();
}
public void insertCBox(int tableNumber, CBox checkBox) {
ContentValues cv = new ContentValues();
cv.put(NAME, checkBox.getName());
cv.put(VALUE, checkBox.getStatus());
cv.put(VALUE2, checkBox.getText());
database.insert(dbHelper.getTableName(tableNumber), NAME, cv);
Log.i(TAG, "Contact added successfully.");
}
public void deleteCheckBox(int tableNumber, int id) {
database.delete(dbHelper.getTableName(tableNumber), dbHelper.getRowIdName(tableNumber) + "=" + id, null);
}
public void updateCheckBox(int tableNumber, int id,int name,int state, String text) {
ContentValues cv = new ContentValues();
cv.put(NAME, name);
cv.put(VALUE, state);
cv.put(VALUE2, text);
database.update(dbHelper.getTableName(tableNumber), cv, dbHelper.getRowIdName(tableNumber) + "=" + id, null);
}
public CBox getCBox(int tableNumber, int id){
Log.i(TAG, "getCBOX started");
Cursor cursor = database.query(dbHelper.getTableName(tableNumber), null, null, null, null, null, null);
Log.i(TAG, "cursor query done");
cursor.moveToFirst();
cursor.moveToPosition(id-1);
Log.i(TAG, "cursor is here: "+ cursor.getPosition());
// cursor.moveToPosition(id--);
Log.i(TAG, "cursor moved to position successfully "+ id--);
CBox CBox = cursorToContact(cursor);
Log.i(TAG, "cursor to contact done");
cursor.close();
Log.i(TAG, "cursor closed");
return CBox;
}
public void clearTable(int tableNumber) {
database.delete(dbHelper.getTableName(tableNumber), null, null);
}
private CBox cursorToContact(Cursor cursor) {
CBox checkBox = new CBox();
Log.i(TAG, "cursor to contact > started");
checkBox.setId(cursor.getInt(0));
Log.i(TAG, "cursor to contact > getInt(0) done " + checkBox.getId());
checkBox.setName(cursor.getInt(1));
Log.i(TAG, "cursor to contact > getInt(1) done " + checkBox.getName());
checkBox.setStatus(cursor.getInt(2));
Log.i(TAG, "cursor to contact > getInt(2) done " + checkBox.getStatus());
checkBox.setText(cursor.getString(3));
Log.i(TAG, "cursor to contact > getString(3) done " + checkBox.getText());
return checkBox;
}
}
在课堂的第三步中，我Mainactivity使用以下代码来使用数据库以及插入、更新和保存数据：
public class MainActivity extends Activity {
private DatabaseHandler dbHandler;
private static final int databaseTableNumber1=1;
private static final int databaseTableNumber2=2;
private static final int databaseTableNumber3=3;
private CBox cBox01;
private CBox cBox02;
private CBox cBox03;
private CBox cBox04;
private boolean firstRunPassed=false;
private SharedPreferences sharedperefs;
private String preferenceName = "Preferences";
@Override
public void onCreate(Bundle icicle) {
super.onCreate(icicle);
Log.i(TAG, "On Create");
setContentView(R.layout.activity_main);
dbHandler = new DatabaseHandler(this);
final Button saveButton = (Button) findViewById(R.id.saveButton);
saveButton.setOnClickListener(new OnClickListener() {
@Override
public void onClick(View v) {
dbHandler.open();
int state;
String text;
CheckBox checkBox01= (CheckBox) findViewById(R.id.checkBox1);
if(checkBox01.isChecked()) state=1; else state=0;
dbHandler.updateCheckBox(databaseTableNumber1,1,R.id.checkBox1,state,"");
RadioGroup radioGroup01=(RadioGroup) findViewById(R.id.radioGroup1);
state= radioGroup01.getCheckedRadioButtonId();
dbHandler.updateCheckBox(databaseTableNumber1,2, R.id.radioGroup1, state,"");
EditText editText01=(EditText) findViewById(R.id.editText1);
text=editText01.getText().toString();
dbHandler.updateCheckBox(databaseTableNumber2,1, R.id.editText1,state,text);
ToggleButton toggleButton01 =(ToggleButton) findViewById(R.id.toggleButton1);
if(toggleButton01.isChecked()) state=1; else state=0;
dbHandler.updateCheckBox(databaseTableNumber3,1,R.id.toggleButton1,state,"");
dbHandler.close();
}
});
}
@Override
protected void onPause(){
super.onPause();
Log.i(TAG, "On Pause");
sharedperefs = getSharedPreferences(preferenceName, MODE_PRIVATE);
SharedPreferences.Editor editor =sharedperefs.edit();
firstRunPassed=true;
editor.putBoolean("firstRunPassed", firstRunPassed);
editor.commit();
}
@Override
protected void onResume() {
super.onResume();
Log.i(TAG, "On Resume");
sharedperefs=getSharedPreferences(preferenceName, MODE_PRIVATE);
firstRunPassed=sharedperefs.getBoolean("firstRunPassed", false);
dbHandler.open();
Log.i(TAG, "dbhandler opened");
if(firstRunPassed){
cBox01=new CBox();
cBox01=dbHandler.getCBox(databaseTableNumber1,1);
CheckBox checkBox01= (CheckBox) findViewById(R.id.checkBox1);
if(cBox01.getStatus()==1)
checkBox01.setChecked(true);
else
checkBox01.setChecked(false);
cBox02=new CBox();
cBox02=dbHandler.getCBox(databaseTableNumber1,2);
RadioGroup radioGroup01=(RadioGroup) findViewById(R.id.radioGroup1);
radioGroup01.check(cBox02.getStatus());
cBox03=new CBox();
cBox03=dbHandler.getCBox(databaseTableNumber2,4);
EditText editText01=(EditText) findViewById(R.id.editText1);
editText01.setText(cBox03.getText());
cBox04=new CBox();
cBox04=dbHandler.getCBox(databaseTableNumber3,1);
ToggleButton toggleButton01 =(ToggleButton) findViewById(R.id.toggleButton1);
if(cBox04.getStatus()==1)
toggleButton01.setChecked(true);
else
toggleButton01.setChecked(false);
} else {
cBox01 = new CBox(); cBox01.setId(1); cBox01.setName(R.id.checkBox1); cBox01.setStatus(0); cBox01.setText(""); dbHandler.insertCBox(databaseTableNumber1,cBox01);
cBox02 = new CBox(); cBox02.setId(2); cBox02.setName(R.id.radioGroup1); cBox02.setStatus(0); cBox02.setText(""); dbHandler.insertCBox(databaseTableNumber1,cBox02);
cBox03 = new CBox(); cBox03.setId(1); cBox03.setName(R.id.editText1); cBox03.setStatus(0); cBox03.setText("Start please"); dbHandler.insertCBox(databaseTableNumber2,cBox03);
cBox04 = new CBox(); cBox04.setId(1); cBox04.setName(R.id.toggleButton1); cBox04.setStatus(0); cBox04.setText(""); dbHandler.insertCBox(databaseTableNumber3,cBox04);
}
dbHandler.close();
Log.i(TAG, "dbhandler closed");
}
}
这CBox是我的最后一课，用于设置和获取数据单元格：
public class CBox {
private int id;
private int name;
private int Status;
private String text;
private String unit;
public long getId() {
return id;
}
public String getIdInString() {
return Long.toString(id);
}
public int getName() {
return name;
}
public int getStatus() {
return Status;
}
public String getText() {
return text;
}
public String getUnit() {
return unit;
}
public void setId(int id) {
this.id = id;
}
public void setName(int name) {
this.name = name;
}
public void setStatus(int status) {
this.Status = status;
}
public void setText(String text) {
this.text = text;
}
public void setUnit(String unit) {
this.unit = unit;
}
}