插入ing时空指针异常数据库Android

Question

我已经在android中实现了一个数据库，当我试图插入一个用户到数据库时，我得到了一个N​​ull Poiner异常。我已经调试了有关详细信息的用户输入，并且那里有信息。

这是我的DbManager.java类

package com.fyp.run_race; 

import android.content.ContentValues; 
import android.content.Context; 
import android.database.Cursor; 
import android.database.SQLException; 
import android.database.sqlite.SQLiteDatabase; 

public class DbManager 
{ 

public static final String KEY_USER_ID = "_id"; 
public static final String KEY_USER_EMAIL = "email"; 
public static final String KEY_USER_WEIGHT = "weight"; 
public static final String KEY_USER_HEIGHT = "height"; 

public static final String KEY_TRACK_ID = "_id"; 
public static final String KEY_TRACK_FILEPATH = "file_path"; 
public static final String KEY_TRACK_NAME = "track_name"; 
public static final String KEY_TRACK_LOCATION = "location"; 
public static final String KEY_TRACK_TYPE = "track_type"; 
public static final String KEY_TRACK_CALORIES = "calories"; 
public static final String KEY_TRACK_DISTANCE = "distance"; 
public static final String KEY_TRACK_MAX_SPEED = "max_speed"; 
public static final String KEY_TRACK_AVG_SPEED = "avg_speed"; 

static final String USER_TABLE = "USERINFO"; 
static final String TRACK_TABLE = "TRACK"; 

private Context context; 

private DbHelper dbHelper; 
private SQLiteDatabase db; 

public DbManager(Context cnxt) 
{ 
    this.context = cnxt; 
} 

public DbManager open() throws SQLException 
{ 
    dbHelper = new DbHelper(context); 
    db = dbHelper.getReadableDatabase(); 

    return this; 
} 

public void close() 
{ 
    dbHelper.close(); 
} 

public long createUser(String email, float weight, float height) 
{ 
    ContentValues initialValues = new ContentValues(); 
    initialValues.put(KEY_USER_EMAIL, email); 
    initialValues.put(KEY_USER_WEIGHT, weight); 
    initialValues.put(KEY_USER_HEIGHT, height); 
    return db.insert(USER_TABLE, null, initialValues); 
} 

public long createTrack(String filePath,String trackName, String location, String trackType, float calories, float distance, float avgSpeed, float maxSpeed) 
{ 
    ContentValues initialValues = new ContentValues(); 
    initialValues.put(KEY_TRACK_FILEPATH, filePath); 
    initialValues.put(KEY_TRACK_NAME, trackName); 
    initialValues.put(KEY_TRACK_LOCATION, location); 
    initialValues.put(KEY_TRACK_TYPE, trackType); 
    initialValues.put(KEY_TRACK_CALORIES, calories); 
    initialValues.put(KEY_TRACK_DISTANCE, distance); 
    initialValues.put(KEY_TRACK_AVG_SPEED, avgSpeed); 
    initialValues.put(KEY_TRACK_MAX_SPEED, maxSpeed); 
    return db.insert(TRACK_TABLE, null, initialValues); 
} 

public boolean deleteUser(long rowId) 
{ 
    return db.delete(USER_TABLE, KEY_USER_ID+"="+rowId, null) > 0 ; 
} 

public boolean deleteTrack(long rowId) 
{ 
    return db.delete(TRACK_TABLE, KEY_TRACK_ID+"="+rowId, null) > 0 ; 
} 

public Cursor getAllUsers() 
{ 
    return db.query(true, USER_TABLE, new String[]{KEY_USER_ID,KEY_USER_EMAIL,KEY_USER_WEIGHT,KEY_USER_HEIGHT }, null, null, null, null, null, null); 
} 

public Cursor getAllTracks() 
{ 
    return db.query(true, TRACK_TABLE, new String[]{KEY_TRACK_ID,KEY_TRACK_FILEPATH,KEY_TRACK_NAME,KEY_TRACK_LOCATION,KEY_TRACK_TYPE, KEY_TRACK_CALORIES, KEY_TRACK_DISTANCE, KEY_TRACK_AVG_SPEED,KEY_TRACK_MAX_SPEED}, null, null, null, null, null, null); 
} 

public Cursor getUser(long rowId) 
{ 
    Cursor myCursor = db.query(true, USER_TABLE, new String[]{KEY_USER_ID,KEY_USER_EMAIL,KEY_USER_WEIGHT,KEY_USER_HEIGHT }, KEY_USER_ID + "="+ rowId, null, null, null, null, null); 

    if(myCursor != null) 
    { 
     myCursor.moveToFirst(); 
    } 

    return myCursor; 
} 

public Cursor getTrack(long rowId) 
{ 
    Cursor myCursor = db.query(true, TRACK_TABLE, new String[]{KEY_TRACK_ID,KEY_TRACK_FILEPATH,KEY_TRACK_NAME,KEY_TRACK_LOCATION,KEY_TRACK_TYPE, KEY_TRACK_CALORIES, KEY_TRACK_DISTANCE, KEY_TRACK_AVG_SPEED,KEY_TRACK_MAX_SPEED}, KEY_TRACK_ID+ "=" + rowId, null, 
      null, null, null, null); 

    if(myCursor != null) 
    { 
     myCursor.moveToFirst(); 
    } 

    return myCursor; 
} 

public boolean updateUser(long rowId,String email, float weight, float height) 
{ 
    ContentValues args = new ContentValues(); 

    args.put(KEY_USER_EMAIL, email); 
    args.put(KEY_USER_WEIGHT, weight); 
    args.put(KEY_USER_HEIGHT, height); 

    return db.update(USER_TABLE, args, KEY_USER_ID + "=" + rowId, null) > 0; 
} 

}

的logcat的是确定在db管理器类

和线66在Enter_User_Details.java类，这是long id = db.createUser(vEmail, Float.parseFloat(vWeight), Float.parseFloat(vHeight));线59 return db.insert(USER_TABLE, null, initialValues);

这里是完整的Enter_User_Details类

package com.fyp.run_race; 

import java.util.regex.Matcher; 
import java.util.regex.Pattern; 

import android.app.Activity; 
import android.content.Intent; 
import android.os.Bundle; 
import android.text.Editable; 
import android.view.View; 
import android.view.View.OnClickListener; 
import android.widget.Button; 
import android.widget.EditText; 
import android.widget.Toast; 

import com.fyp.run_race.DbManager; 

public class Enter_User_Details extends Activity 
{ 
private DbManager db; 
Long rowId = null; 
EditText email,weight,height; 
Button confirm,clear; 
String vEmail, vWeight,vHeight; 
boolean emailCheck; 

public void onCreate(Bundle savedInstanceState) 
{ 
    super.onCreate(savedInstanceState); 
    setContentView(R.layout.user_details); 
    db = new DbManager(this); 

    email = (EditText)findViewById(R.id.EmailEntry); 
    weight = (EditText)findViewById(R.id.Weight); 
    height = (EditText)findViewById(R.id.Height); 
    confirm = (Button)findViewById(R.id.ConfirmBtn); 
    clear = (Button)findViewById(R.id.ClearBtn); 



    confirm.setOnClickListener(new OnClickListener() 
    { 

     @Override 
     public void onClick(View arg0) 
     { 
      // TODO Auto-generated method stub 
      vEmail = email.getText().toString(); 
      vWeight = weight.getText().toString(); 
      vHeight = height.getText().toString(); 

      if(vEmail.equalsIgnoreCase("")||vWeight.equalsIgnoreCase("")||vHeight.equalsIgnoreCase("")) 
      { 
       Toast.makeText(Enter_User_Details.this, "All fields are required", Toast.LENGTH_LONG).show(); 
      } 

      if(isNumeric(vWeight) == true && isNumeric(vHeight) == true) 
      { 
       Toast.makeText(Enter_User_Details.this, "Weight or Height must be a number", Toast.LENGTH_LONG).show(); 
      } 

      checkEmail(vEmail); 
      if(emailCheck == true) 
      { 
       System.out.println("Email: "+vEmail+" Weight: "+Float.parseFloat(vWeight)+" Height: "+Float.parseFloat(vHeight)); 
       long id = db.createUser(vEmail, Float.parseFloat(vWeight), Float.parseFloat(vHeight)); 
       db.close(); 
       Intent i = new Intent(Enter_User_Details.this, Begin_Run.class); 
       startActivity(i); 
      } 


     } 



    }); 

} 

public static boolean isNumeric(String str) 
{ 
    try 
    { 
     float f = Float.parseFloat(str); 
    } 

    catch(NumberFormatException nfe) 
    { 
     return false; 
    } 

    return true; 
} 

private void checkEmail(String vEmail) 
{ 
    // TODO Auto-generated method stub 
    Pattern pattern = Pattern.compile(".+@.+\\.[a-z]+"); 
    Matcher matcher = pattern.matcher(vEmail); 
    emailCheck = matcher.matches(); 

} 

}

这里是logcat的输出包括的System.out.println表明用户输入的Fileds实际上在他们的数据

02-12 14:36:29.802: I/System.out(1693): Email: sean.w.hannon@gmail.com Weight: 75.5 Height: 160.5 
02-12 14:36:29.802: D/AndroidRuntime(1693): Shutting down VM 
02-12 14:36:29.802: W/dalvikvm(1693): threadid=1: thread exiting with uncaught exception (group=0x4001d800) 
02-12 14:36:29.812: E/AndroidRuntime(1693): FATAL EXCEPTION: main 
02-12 14:36:29.812: E/AndroidRuntime(1693): java.lang.NullPointerException 
02-12 14:36:29.812: E/AndroidRuntime(1693):  at com.fyp.run_race.DbManager.createUser(DbManager.java:59) 
02-12 14:36:29.812: E/AndroidRuntime(1693):  at com.fyp.run_race.Enter_User_Details$1.onClick(Enter_User_Details.java:66) 
02-12 14:36:29.812: E/AndroidRuntime(1693):  at android.view.View.performClick(View.java:2408) 
02-12 14:36:29.812: E/AndroidRuntime(1693):  at android.view.View$PerformClick.run(View.java:8816) 
02-12 14:36:29.812: E/AndroidRuntime(1693):  at android.os.Handler.handleCallback(Handler.java:587) 
02-12 14:36:29.812: E/AndroidRuntime(1693):  at android.os.Handler.dispatchMessage(Handler.java:92) 
02-12 14:36:29.812: E/AndroidRuntime(1693):  at android.os.Looper.loop(Looper.java:123) 
02-12 14:36:29.812: E/AndroidRuntime(1693):  at android.app.ActivityThread.main(ActivityThread.java:4627) 
02-12 14:36:29.812: E/AndroidRuntime(1693):  at java.lang.reflect.Method.invokeNative(Native Method) 
02-12 14:36:29.812: E/AndroidRuntime(1693):  at java.lang.reflect.Method.invoke(Method.java:521) 
02-12 14:36:29.812: E/AndroidRuntime(1693):  at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:868) 
02-12 14:36:29.812: E/AndroidRuntime(1693):  at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:626) 
02-12 14:36:29.812: E/AndroidRuntime(1693):  at dalvik.system.NativeStart.main(Native Method) 

Answer 1

我觉得DbHelper dbHelper是null因为你永远不要拨打DbManager.open()！

尝试添加db.open()之前db.createUser(..)在Enter_User_Details。