Android :bundle passing from two activities to another activity

I have mainly 4 activities in my app(Login,signup,buy_nw and buy_ltr).The Person wish to login should signup first.The details entered in signup page will saved to a sqLite database.I need to automatically fill all the details of member asked in buy_nw and buy_ltr directly from database on clicking login button.I tried using bundle passing.It not working properly.Please help me out.

Login.java

public class login extends Activity{
EditText edt1,edt2;
Button btn1,btn2;
SQLiteDatabase mydb;
CheckBox chkbx;
SharedPreferences loginPreferences;
SharedPreferences.Editor loginPrefsEditor;
Boolean saveLogin;
@Override
protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.login);
    btn1=(Button)findViewById(R.id.loginbtn);
    btn2=(Button)findViewById(R.id.signupbtn);
    edt1=(EditText)findViewById(R.id.useredit);
    edt2=(EditText)findViewById(R.id.passedit);
    chkbx=(CheckBox)findViewById(R.id.checkbox);
    mydb=this.openOrCreateDatabase("shopping", MODE_PRIVATE, null); 
    mydb.execSQL("CREATE TABLE IF NOT EXISTS contacts(name varchar,adrs varchar,city varchar,pin varchar,uname varchar,pass varchar,mob varchar,eid varchar)");


    loginPreferences = getSharedPreferences("loginPrefs", MODE_PRIVATE);
    loginPrefsEditor = loginPreferences.edit();
    saveLogin = loginPreferences.getBoolean("saveLogin", false);
    if (saveLogin == true) {
        edt1.setText(loginPreferences.getString("username", ""));
        edt2.setText(loginPreferences.getString("password", ""));
        chkbx.setChecked(true);
    }

    btn1.setOnClickListener(new OnClickListener() {

        @Override
        public void onClick(View v) {


            // TODO Auto-generated method stub

            String usr=edt1.getText().toString();
            String pwd=edt2.getText().toString();
            Cursor cur=mydb.rawQuery("select * from contacts where uname='"+usr+"'",null);

            final String[] usrnme = new String[cur.getCount()];

            int j = 0;
            while(cur.moveToNext())
            {
                String user = cur.getString(cur.getColumnIndex("uname"));
                usrnme[j] = user;
                j++;
            }

            if (v==btn1) {
                InputMethodManager imm=(InputMethodManager)getSystemService(Context.INPUT_METHOD_SERVICE);
                imm.hideSoftInputFromWindow(edt1.getWindowToken(),0);

                if (chkbx.isChecked()) {
                    loginPrefsEditor.putBoolean("saveLogin",true);
                    loginPrefsEditor.putString("username",usr);
                    loginPrefsEditor.putString("password",pwd);
                    loginPrefsEditor.commit();
                } else {
                    loginPrefsEditor.clear();
                    loginPrefsEditor.commit();
                }    
           }
            while (cur.moveToNext()) 
            {
            String pas=cur.getString(cur.getColumnIndex("pass"));

            if (pwd.equals(pas))
            {
            String topas = usrnme[j];
                Intent in=new Intent(getApplicationContext(),product_display.class);
                Bundle bn = new Bundle();
                bn.putString("key",topas);
                in.putExtras(bn);
                startActivity(in);
            } 
            else
            {

                Toast.makeText(login.this,"invalid username or password",Toast.LENGTH_SHORT).show();
            }

         }

  }
    });
              btn2.setOnClickListener(new OnClickListener() {

        @Override
        public void onClick(View v) {
            // TODO Auto-generated method stub
            Intent in=new Intent(login.this,signup.class);
            startActivity(in);

          }
        });
  }


       }    


  }

buy_nw.java

public class buy_nw extends Activity {
EditText edt1,edt2,edt3,edt4,edt5;
Button btn;
SQLiteDatabase mydb;
@Override
protected void onCreate(Bundle savedInstanceState) {
    // TODO Auto-generated method stub
    super.onCreate(savedInstanceState);
    setContentView(R.layout.buy_nw);
    edt1=(EditText)findViewById(R.id.nameedit);
    edt2=(EditText)findViewById(R.id.addrsedit);
    edt3=(EditText)findViewById(R.id.cityedit);
    edt4=(EditText)findViewById(R.id.pincodedit);
    edt5=(EditText)findViewById(R.id.quantityedit);
    btn=(Button)findViewById(R.id.cnfm_ordr);

    Intent in=getIntent();
    Bundle bn=in.getExtras();
    String list=bn.getString("key");

    mydb=this.openOrCreateDatabase("reg", MODE_PRIVATE, null);
    mydb.execSQL("CREATE TABLE IF NOT EXISTS contacts(name varchar,adrs varchar,city varchar,pin varchar,uname varchar,pass varchar,mob varchar,eid varchar)");

    Cursor cur=mydb.rawQuery("SELECT * FROM contacts WHERE uname='"+list+"' ", null);
    while (cur.moveToNext()) {



        String nm=cur.getString(cur.getColumnIndex("name"));
        edt1.setText(nm);
        String ad=cur.getString(cur.getColumnIndex("adrs"));
        edt2.setText(ad);
        String cty=cur.getString(cur.getColumnIndex("city"));
        edt3.setText(cty);
        String pc=cur.getString(cur.getColumnIndex("pin"));
        edt4.setText(pc);
        String qty=cur.getString(cur.getColumnIndex("name"));
        edt5.setText(qty);

}
    btn.setOnClickListener(new OnClickListener() {

        @Override
        public void onClick(View v) {
            // TODO Auto-generated method stub

            Intent emailIntent = new Intent(android.content.Intent.ACTION_SEND);
             String[] recipients = new String[]{"my@email.com", "",};
              emailIntent.putExtra(android.content.Intent.EXTRA_EMAIL, recipients);
              emailIntent.putExtra(android.content.Intent.EXTRA_SUBJECT, "Test");
              emailIntent.putExtra(android.content.Intent.EXTRA_TEXT, "This is email's message");
              emailIntent.setType("text/plain");
              startActivity(Intent.createChooser(emailIntent, "Send mail..."));
              finish();

        }
    });
}

}