SQlite Database File not loading

Question

I have been having trouble with my accessing my database file, I'm not exactly sure where the issue is and i've looked through other answers to this error with no success . I think it's something to do with the main activity class not creating an instance of the IntDatabaseHelper at the right time , but i have been looking at everything for so long that I'm not exactly sure whats wrong . all my code and my Logcat output is below.

MainActivity

public class MainActivity extends AppCompatActivity {
IntDataBaseHelper intDataBaseHelper;

ListView lstJob;
ArrayAdapter<String> mAdapter;





   @Override
   protected void onCreate(Bundle savedInstanceState) {
   super.onCreate(savedInstanceState);
   setContentView(R.layout.activity_main);

       intDataBaseHelper  = new IntDataBaseHelper(this);

    /*create instance of db helper and jobs
    Create the database (only if it doesn't exists)
    does so by copying from the assets */

    LoadJobList();
    if (CopyDBFromAssets.createDataBase(this,IntDataBaseHelper.DB_TABLE)) {
       // problem area
       // Get the data from the database
        lstJob = (ListView) findViewById(R.id.lstJob);
    ArrayList<String> jobs =  intDataBaseHelper.getJobList();
       for (String s : jobs) {
           Log.d("JobList ", "Found Job " + s);
          }
       } else {
           throw new RuntimeException("No Usable Database exists or was copied from the assets.");
       }

   }
  // loads job to screen
      public void LoadJobList() {
      ArrayList<String> JobList = intDataBaseHelper.getJobList();
      if (mAdapter == null) {
          mAdapter = new ArrayAdapter<>(this,R.layout.header,R.id.header);
          mAdapter = new ArrayAdapter<>(this,R.layout.row,R.id.BtnComplete,JobList);
          mAdapter = new ArrayAdapter<>(this, R.layout.row, R.id.Job_name,JobList);
          lstJob.setAdapter(mAdapter);
      } else
          {
          mAdapter.clear();
          mAdapter.addAll(JobList);
          mAdapter.notifyDataSetChanged();
      }
  }

}

IntDataBase

public class IntDataBaseHelper extends SQLiteOpenHelper{


private static  String DB_PATH ="//data/data/com.example.joelg.clapp/databases";
public static  String DB_NAME = "JobList.db";
public static  String DB_COLUMN = "jobNM";
public static  String DB_TABLE = "job";
private static  String DB_JOB_DETAILS = "jobDetails";
private static  String DB_ISDONE = "jobIsDone";
private  Context jobContext;
private SQLiteDatabase JobListDatabase;




    /**
     * constructor creater
     */
    public IntDataBaseHelper (Context context) {
        super (context, DB_NAME,null, 1);
        this.jobContext = context;
        DB_PATH = jobContext.getDatabasePath(DB_NAME).getPath();
    }


    public void OpenDataBase() {
        // open the database
        String JobListPath = DB_PATH;
        JobListDatabase = SQLiteDatabase.openDatabase(JobListPath,null,SQLiteDatabase.OPEN_READONLY);
    }


    // Getting Job Count
    public  ArrayList<String> getJobList() {
        ArrayList<String> JobList = new ArrayList<>();
        SQLiteDatabase db = this.getReadableDatabase();
        Cursor cursor =  db.query(DB_TABLE,new String[]
                {DB_COLUMN},null,null,null,null,null);
            while(cursor.moveToNext()){
            int index = cursor.getColumnIndex(DB_COLUMN);
            JobList.add(cursor.getString(index));
        }

        cursor.close();
        db.close();
        return JobList;
    }


    // Gets the job state if it has been competed or not
public ArrayList<String> getIsDone() {
    ArrayList<String>  IsDone = new ArrayList<>();
    SQLiteDatabase db = this.getReadableDatabase();
    Cursor cursor = db.query(DB_TABLE,new String[]{DB_ISDONE},null,null,null,null,null);
    while(cursor.moveToNext()){
        int index = cursor.getColumnIndex(DB_ISDONE);
        IsDone.add(cursor.getString(index));
    }

    cursor.close();
    db.close();
    return IsDone;
}




    @Override
    public synchronized void close(){

        if(JobListDatabase !=null){
            JobListDatabase.close();
            super.close();

        }
    }
    @Override
    public  void onCreate(SQLiteDatabase db) {

    }
    @Override
    public void onUpgrade(SQLiteDatabase db, int oldVersion, int newVersion) {
    }
}

LogCat

java.lang.RuntimeException: Unable to start activity ComponentInfo{com.example.joelg.clapp/com.example.joelg.clapp.MainActivity}: java.lang.NullPointerException: Attempt to invoke virtual method 'void android.widget.ListView.setAdapter(android.widget.ListAdapter)' on a null object reference
                                                     at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2817)
                                                     at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2892)
                                                     at android.app.ActivityThread.-wrap11(Unknown Source:0)
                                                     at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1593)
                                                     at android.os.Handler.dispatchMessage(Handler.java:105)
                                                     at android.os.Looper.loop(Looper.java:164)
                                                     at android.app.ActivityThread.main(ActivityThread.java:6541)
                                                     at java.lang.reflect.Method.invoke(Native Method)
                                                     at com.android.internal.os.Zygote$MethodAndArgsCaller.run(Zygote.java:240)
                                                     at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:767)
                                                  Caused by: java.lang.NullPointerException: Attempt to invoke virtual method 'void android.widget.ListView.setAdapter(android.widget.ListAdapter)' on a null object reference
                                                     at com.example.joelg.clapp.MainActivity.LoadJobList(MainActivity.java:55)
                                                     at com.example.joelg.clapp.MainActivity.onCreate(MainActivity.java:34)
                                                     at android.app.Activity.performCreate(Activity.java:6975)
                                                     at android.app.Instrumentation.callActivityOnCreate(Instrumentation.java:1213)
                                                     at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2770)
                                                     at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2892) 
                                                     at android.app.ActivityThread.-wrap11(Unknown Source:0) 
                                                     at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1593) 
                                                     at android.os.Handler.dispatchMessage(Handler.java:105) 
                                                     at android.os.Looper.loop(Looper.java:164) 
                                                     at android.app.ActivityThread.main(ActivityThread.java:6541) 
                                                     at java.lang.reflect.Method.invoke(Native Method) 
                                                     At com.android.internal.os.Zygote$MethodAndArgsCaller.run(Zygote.java:240) 
                                                     at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:767)

Possible duplicate of What is a NullPointerException, and how do I fix it? — Ratilal Chopda
– Ratilal Chopda, Commented Nov 7, 2017 at 6:58

KeLiuyue · Accepted Answer · 2017-11-07 07:48:22Z

1

You problem is

Caused by: java.lang.NullPointerException: Attempt to invoke virtual method 'void android.widget.ListView.setAdapter(android.widget.ListAdapter)' on a null object reference

It was at lstJob.setAdapter(mAdapter); .

So you should check lstJob init or not .

You should do this .

Call LoadJobList after findViewById method .

lstJob = (ListView) findViewById(R.id.lstJob);
LoadJobList();

Edit

You should implement onCreate method and onUpdate method in your IntDataBaseHelper class .

When you have

android.database.sqlite.SQLiteException: no such table: job (code 1)

The reason is that when you add a table or modify the table, there is no update version, after doing the above operation, the database version should be added, each time you make a change, you should add one.

edited Nov 7, 2017 at 7:48

answered Nov 7, 2017 at 6:58

KeLiuyue

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7 Comments

Ratilal Chopda Over a year ago

start using your close votes rights and stop farming reputation

Joel Geri Over a year ago

Thanks for this now im getting " android.database.sqlite.SQLiteException: no such table: job (code 1): , while compiling: SELECT jobNM FROM job"

Joel Geri Over a year ago

Im not meaning to farm reputation sorry

KeLiuyue Over a year ago

You should implement onCreate method and onUpdate method in your IntDataBaseHelper class .

KeLiuyue Over a year ago

Thank you for your comment .Enjoy coding.@RatilalChopda

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