我最近一直在做一个android数据库应用程序项目。当我试图执行时。我无法在DDMS的文件浏览器中找到文件夹'databases'。我检查了以下路径/数据/数据/包名/数据库，但在那里我找不到数据库文件夹和我的数据库文件。
我附加了数据库助手类的代码 如果有任何错误阻止我创建数据库或者我的日食错误，请帮助我。因为即使我现有的一些项目也没有出现在其中的数据库文件夹中。
DBclass.java：
package pack.andyxdb;
import android.content.ContentValues;
import android.content.Context;
import android.database.Cursor;
import android.database.SQLException;
import android.database.sqlite.SQLiteDatabase;
import android.database.sqlite.SQLiteOpenHelper;
import android.util.Log;
public class DBclass {
public static final String KEY_TIMESTAMP = "Timestamp";
public static final String KEY_UNIQUEID = "UniqueID";
public static final String KEY_DEVICETYPE = "Devicetype";
public static final String KEY_RSSI = "RSSI";
private static final String DATABASE_NAME = "DannyZ.db";
private static final String DATABASE_TABLE = "Data";
private static final int DATABASE_VERSION = 1;
private final Context ourContext;
private DbHelper dbh;
private SQLiteDatabase odb;
private static final String USER_MASTER_CREATE =
"CREATE TABLE IF NOT EXISTS " + DATABASE_TABLE+ "("
+ KEY_TIMESTAMP + " INTEGER ,"
+ KEY_UNIQUEID + " INTEGER, " + KEY_DEVICETYPE + " TEXT, " + KEY_RSSI + " INTEGER PRIMARY KEY )";
//CREATE TABLE `DannyZ` (
private static class DbHelper extends SQLiteOpenHelper {
public DbHelper(Context context) {
super(context, DATABASE_NAME, null, DATABASE_VERSION);
}
@Override
public void onCreate(SQLiteDatabase db) {
db.execSQL(USER_MASTER_CREATE);
}
@Override
public void onUpgrade(SQLiteDatabase db, int oldVersion, int newVersion) {
// if DATABASE VERSION changes
// Drop old tables and call super.onCreate()
}
}
public DBclass(Context c) {
ourContext = c;
dbh = new DbHelper(ourContext);
}
public DBclass open() throws SQLException {
odb = dbh.getWritableDatabase();
return this;
}
public void close() {
dbh.close();
}
public long insertrecord(int timestamp, int uniqueID,String Device, int RSSI) throws SQLException{
// Log.d("", col1);
// Log.d("", col2);
ContentValues IV = new ContentValues();
IV.put(KEY_TIMESTAMP, timestamp);
IV.put(KEY_UNIQUEID, uniqueID );
IV.put(KEY_DEVICETYPE, Device != "");
IV.put(KEY_RSSI, RSSI );
return odb.insert(DATABASE_TABLE, null, IV);
// returns a number >0 if inserting data is successful
}
public void updateRow(long rowID, String col1, String col2,String col3,String col4) {
ContentValues values = new ContentValues();
values.put(KEY_TIMESTAMP, col1);
values.put(KEY_UNIQUEID, col2);
values.put(KEY_DEVICETYPE, col3);
values.put(KEY_RSSI, col4);
try {
odb.update(DATABASE_TABLE, values, KEY_RSSI + "=" + rowID, null);
} catch (Exception e) {
}
}
public boolean delete() {
return odb.delete(DATABASE_TABLE, null, null) > 0;
}
public Cursor getAllTitles() {
// using simple SQL query
return odb.rawQuery("select * from " + DATABASE_TABLE + "ORDER BY "+KEY_RSSI, null);
}
public Cursor getallCols(String id) throws SQLException {
Cursor mCursor = odb.query(DATABASE_TABLE, new String[] { KEY_TIMESTAMP,
KEY_UNIQUEID, KEY_DEVICETYPE, KEY_RSSI }, null, null, null, null, null);
Log.e("getallcols zmv", "opening successfull");
return mCursor;
}
public Cursor getColsById(String id) throws SQLException {
Cursor mCursor = odb.query(DATABASE_TABLE, new String[] { KEY_TIMESTAMP,
KEY_UNIQUEID,KEY_DEVICETYPE }, KEY_RSSI + " = " + id, null, null, null, null);
Log.e("getallcols zmv", "opening successfull");
return mCursor;
}
}
我的MainActivity.java代码也在这里。在这里，我尝试使用提交按钮将数据插入数据库。当我按下提交按钮时，应用程序不会停留很长时间并且说不幸的是myapp已经停止。我很关心我的数据库是否被创建？
请帮助我谢谢
MainActivity：
public class MainActivity extends Activity {
private ListView list_lv;
private EditText txt1;
private EditText txt2;
private EditText txt3;
private EditText txt4;
private Button btn1;
private Button btn2;
private DBclass db;
private ArrayList<String> collist_1;
private ArrayList<String> collist_2;
private ArrayList<String> collist_3;
private ArrayList<String> collist_4;
@Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
collist_1 = new ArrayList<String>();
collist_2 = new ArrayList<String>();
collist_3 = new ArrayList<String>();
collist_4 = new ArrayList<String>();
items();
// getData();
}
private void items() {
btn1 = (Button) findViewById(R.id.button1);
btn2 = (Button) findViewById(R.id.button2);
txt1 = (EditText) findViewById(R.id.editText1);
txt2 = (EditText) findViewById(R.id.editText2);
txt3 = (EditText) findViewById(R.id.editText3);
txt4 = (EditText) findViewById(R.id.editText4);
// list_lv = (ListView) findViewById(R.id.dblist);
btn2.setOnClickListener(new OnClickListener() {
@Override
public void onClick(View v) {
//getData();
viewData();
}
private void viewData() {
Intent i = new Intent(MainActivity.this, viewActivity.class);
startActivity(i);
}
});
btn1.setOnClickListener(new OnClickListener() {
@Override
public void onClick(View v) {
submitData();
}
});
}
protected void submitData() {
int a = Integer.parseInt( txt1.getText().toString());
int b = Integer.parseInt( txt2.getText().toString());
String c = txt3.getText().toString();
int d = Integer.parseInt( txt4.getText().toString());
db = new DBclass(this);
long num = 0;
try {
db.open();
num = db.insertrecord(a, b,c,d);
db.close();
} catch (SQLException e) {
Toast.makeText(this, "Error Duplicate value"+e,2000).show();
} finally {
//getData();
}
if (num > 0)
Toast.makeText(this, "Row number: " + num, 2000).show();
else if (num == -1)
Toast.makeText(this, "Error Duplicate value", 4000).show();
else
Toast.makeText(this, "Error while inserting", 2000).show();
}
}
答案 0 :(得分：-2)
在您的activity onCreate方法中创建辅助类的对象，以便在Android应用程序中创建数据库文件
DBclass db=new DBclass(context);
希望这会有所帮助。