declared value from other java file and use it to another java file?

[funnym3]

how to get the declared value from other java file and use it to another java file? like I want to show the user's real name using the textView when he/she successfuly login, from the main activity to the welcome page. example "Welcome User". I have tried this but it's not working: Cursor cursor = dataBase.select("SELECT real_name FROM " + TABLE_NAME + " WHERE u_id = '" + COLUMN_NAME1 + "';");
please help

this the code of my homepage.java:

package com.example.howtos;

    import android.os.Bundle;
    import android.app.Activity;
    import android.content.Intent;
    import android.database.Cursor;
//import android.database.Cursor;
    import android.view.View;
    import android.widget.Button;
    import android.widget.TextView;
    import android.widget.Toast;


    public class homepage extends Activity {

    private TextView textView;
    private DatabaseManager dataBase;
    public static final String TABLE_NAME = "users";
    public static final String COLUMN_NAME = "real_name";
    public static final String COLUMN_NAME1 = "u_id";

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

  //get the connection on the 
    dataBase = DatabaseManager.instance();

  //get the id of the textview to show text
    textView = (TextView) findViewById(R.id.textView2);

    Button a = (Button) findViewById (R.id.next1);
    a.setOnClickListener(new View.OnClickListener() {
        @Override    public void onClick(View v) {
     startActivity(new Intent(homepage.this,need.class)); 
        }
});
    Button out = (Button) findViewById (R.id.lo);
    out.setOnClickListener(new View.OnClickListener() {
        @Override    public void onClick(View v) {
     startActivity(new Intent       (homepage.this,MainActivity.class)); 
     Toast.makeText(getApplicationContext(), "Logout    Successful!", Toast.LENGTH_SHORT).show();

        }
    });


    updateTextView();   
}

    public void updateTextView() {

    //get all the available values from the database
        //Cursor cursor = dataBase.select("SELECT   real_name FROM " + TABLE_NAME);
        Cursor cursor = dataBase.select("SELECT     real_name FROM " + TABLE_NAME + " WHERE u_id = '" + COLUMN_NAME1 + "';");


        textView.setText("");

        while(cursor.moveToNext()) {

        //put the values fetched from the database to   the textview
        String s = cursor.getString(cursor.getColumnIndex(COLUMN_NAME));
        textView.append(" " + s);
        }


        cursor.close();
        //----->



    }  
}

and the MainActivity.java code:

package com.example.howtos;



import com.example.howtos.DatabaseManager;
import com.example.howtos.MainActivity;
import com.example.howtos.R;
import com.example.howtos.reg;

import android.os.Bundle;
import android.app.Activity;
import android.content.Intent;
import android.database.Cursor;
import android.database.CursorIndexOutOfBoundsException;
import android.view.View;
import android.widget.Button;
import android.widget.EditText;
import android.widget.TextView;
import android.widget.Toast;


public class MainActivity extends Activity {

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

        final DatabaseManager dataBase;
        dataBase = DatabaseManager.instance();

        Button b = (Button) findViewById (R.id.btn12);
        b.setOnClickListener(new View.OnClickListener()     {
        @Override    public void onClick(View v) {
            try
            {
        final EditText username = (EditText)    findViewById(R.id.editText1);
        final EditText password = (EditText)    findViewById(R.id.editText2);

            final String COLUMN_PW = "password";

        Cursor cursor = dataBase.select("SELECT password    FROM users WHERE username = '" + username.getText   ().toString() + "';");
        cursor.moveToFirst();
        String s = cursor.getString (cursor.getColumnIndex(COLUMN_PW));

        if(password.getText().toString().equals(s))
        //if(password.getText().toString() == s)
        {
startActivity(new Intent(MainActivity.this,homepage.class)); 


Toast.makeText(getApplicationContext(), "Successfully   Login", Toast.LENGTH_SHORT).show();
cursor.close();
}
        else
        {
            Toast.makeText(getApplicationContext(),     "Invalid Username or Password", Toast.LENGTH_SHORT).show    ();
        }
}
catch(CursorIndexOutOfBoundsException e1)
{
Toast.makeText(getApplicationContext(), "Error accessing    database", Toast.LENGTH_SHORT).show();
}       


    }
    });

            TextView r = (TextView) findViewById    (R.id.textView7);
            r.setOnClickListener(new    View.OnClickListener() {
            @Override    public void onClick(View v) {
            startActivity(new Intent    (MainActivity.this,reg.class)); 
            }
            });
         }



}