DBHelper無法解析爲變量

我正在開發一個簡單的註冊登錄系統。在每個類中，每個DbHelper發生的錯誤都很多。錯誤是DBHelper無法解析爲變量。我的資源文件沒有錯誤。我是發佈一個類代碼在這裏DBHelper無法解析爲變量

這裏是我的代碼

package my.DataBase; 

import my.DataBase.R; 

import android.app.Activity; 

import android.content.ContentValues; 

import android.content.Intent; 

import android.database.sqlite.SQLiteDatabase; 

import android.os.Bundle; 

import android.view.View; 

import android.view.View.OnClickListener; 

import android.widget.AdapterView; 

import android.widget.AdapterView.OnItemSelectedListener; 

import android.widget.ArrayAdapter; 
import android.widget.Button; 

import android.widget.EditText; 

import android.widget.Spinner; 

import android.widget.Toast; 


public class Registration extends Activity implements OnClickListener, OnItemSelectedListener 


{ 
// Variable Declaration should be in onCreate() 
private Button mSubmit; 
private Button mCancel; 

private EditText mFname; 
private EditText mLname; 
private EditText mUsername; 
private EditText mPassword; 
private EditText mEmail; 
private Spinner mGender; 
private String Gen; 

protected DBHelper DB = new DBHelper(Registration.this); 

@Override 
protected void onCreate(Bundle savedInstanceState) { 


    super.onCreate(savedInstanceState); 
    setContentView(R.layout.register); 

    //Assignment of UI fields to the variables 
    mSubmit = (Button)findViewById(R.id.submit); 
    mSubmit.setOnClickListener(this); 

    mCancel = (Button)findViewById(R.id.cancel); 
    mCancel.setOnClickListener(this); 

    mFname = (EditText)findViewById(R.id.efname); 
    mLname = (EditText)findViewById(R.id.elname); 

    mUsername = (EditText)findViewById(R.id.reuname); 
    mPassword = (EditText)findViewById(R.id.repass); 
    mEmail = (EditText)findViewById(R.id.eemail); 


    mGender = (Spinner)findViewById(R.id.spinner1); 

    // Spinner method to read the on selected value 
    ArrayAdapter<State> spinnerArrayAdapter = new ArrayAdapter<State>(this, 
       android.R.layout.simple_spinner_item, new State[] { 
      new State("Male"), 
      new State("Female")}); 
    mGender.setAdapter(spinnerArrayAdapter); 
    mGender.setOnItemSelectedListener(this); 
} 



public void onClick(View v) 
{ 

    switch(v.getId()){ 

    case R.id.cancel: 
    Intent i = new Intent(getBaseContext(), LoginActivity.class); 
    startActivity(i); 
    //finish(); 
    break; 

    case R.id.submit: 


    String fname = mFname.getText().toString(); 
    String lname = mLname.getText().toString(); 

    String uname = mUsername.getText().toString(); 
    String pass = mPassword.getText().toString(); 
    String email = mEmail.getText().toString(); 


    boolean invalid = false; 

    if(fname.equals("")) 
    { 
    invalid = true; 
    Toast.makeText(getApplicationContext(), "Enter your Firstname", Toast.LENGTH_SHORT).show(); 
    } 
    else 

    if(lname.equals("")) 
    { 
    invalid = true; 
    Toast.makeText(getApplicationContext(), "Please enter your Lastname", Toast.LENGTH_SHORT).show(); 
    } 
    else 

    if(uname.equals("")) 
    { 
    invalid = true; 
    Toast.makeText(getApplicationContext(), "Please enter your Username", Toast.LENGTH_SHORT).show(); 
    } 
    else 


     if(pass.equals("")) 
    { 
     invalid = true; 
     Toast.makeText(getApplicationContext(), "Please enter your Password", Toast.LENGTH_SHORT).show(); 

    } 
    else 
     if(email.equals("")) 
    { 
    invalid = true; 
    Toast.makeText(getApplicationContext(), "Please enter your Email ID", Toast.LENGTH_SHORT).show(); 
    } 
    else 
     if(invalid == false) 
     { 
     addEntry(fname, lname, Gen, uname, pass, email); 
     Intent i_register = new Intent(Registration.this, LoginActivity.class); 
     startActivity(i_register); 
     //finish(); 
     } 

     break; 
     } 
    } 





public void onDestroy() 
{ 
    super.onDestroy(); 
    DB.close(); 
} 



private void addEntry(String fname, String lname, String Gen, String uname, String pass, String email) 
{ 

    SQLiteDatabase db = DB.getWritableDatabase(); 

    ContentValues values = new ContentValues(); 
    values.put("firstname", fname); 
    values.put("lastname", lname); 
    values.put("gender", Gen); 
    values.put("username", uname); 
    values.put("password", pass); 
    values.put("email", email); 

    try 
    { 
    db.insert(DBHelper.DATABASE_TABLE_NAME, null, values); 

    Toast.makeText(getApplicationContext(), "your details submitted Successfully...", Toast.LENGTH_SHORT).show(); 
    } 
    catch(Exception e) 
    { 
    e.printStackTrace(); 
    } 
} 


    public void onItemSelected(AdapterView<?> parent, View view, int position, long id) 
    { 
     // Get the currently selected State object from the spinner 
     State st = (State)mGender.getSelectedItem(); 

     // Show it via a toast 
     toastState("onItemSelected", st); 
    } 


public void toastState(String name, State st) 
{ 
    if (st != null) 
    { 
    Gen = st.name; 
    //Toast.makeText(getBaseContext(), Gen, Toast.LENGTH_SHORT).show(); 

    } 

} 


public void onNothingSelected(AdapterView<?> arg0) { 
    // TODO Auto-generated method stub 

} 

}

來源

2013-07-05 user2502561

在這裏：DB的方法中

protected DBHelper DB = new DBHelper(Registration.this);

動初始化，而不是在一流水平初始化作爲：

protected DBHelper DB; //<<< declare here 
@Override 
protected void onCreate(Bundle savedInstanceState) { 
    super.onCreate(savedInstanceState); 
    setContentView(R.layout.register); 

    DB = new DBHelper(Registration.this); //<<<< initialize here.. 
    .....

來源

2013-07-05 02:56:28

DBHelper無法解析爲變量

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