Android - สอบถามเรื่อง การ Check Edittext หลาย Edittext ว่าอันไหนมีค่าว่าง และบอกว่า Edittext อันว่างอยู่ อ่าครับ

        // txtUsername,txtPassword,txtName,txtEmail,txtTel
        final EditText txtUsername = (EditText)findViewById(R.id.txtUsername); 
        final EditText txtPassword = (EditText)findViewById(R.id.txtPassword); 
        final EditText txtConPassword = (EditText)findViewById(R.id.txtConPassword); 
        final EditText txtName = (EditText)findViewById(R.id.txtName); 
        final EditText txtEmail = (EditText)findViewById(R.id.txtEmail); 
        final EditText txtTel = (EditText)findViewById(R.id.txtTel); 
        
            
    		// Dialog
        	final AlertDialog.Builder ad = new AlertDialog.Builder(this);

    		ad.setTitle("Error! ");
    		ad.setIcon(android.R.drawable.btn_star_big_on); 
    		ad.setPositiveButton("Close", null);

    		// Check Username
    		if(txtUsername.getText().length() == 0)
    		{
                ad.setMessage("Please input [Username] ");
                ad.show();
                txtUsername.requestFocus();
                return false;
    		}
    		// Check Password
    		if(txtPassword.getText().length() == 0 || txtConPassword.getText().length() == 0 )
    		{
                ad.setMessage("Please input [Password/Confirm Password] ");
                ad.show();
                txtPassword.requestFocus();
                return false;
    		}
    		// Check Password and Confirm Password (Match)
    		if(!txtPassword.getText().toString().equals(txtConPassword.getText().toString()))
    		{
                ad.setMessage("Password and Confirm Password Not Match! ");
                ad.show();
                txtConPassword.requestFocus();
                return false;
    		}
    		// Check Name
    		if(txtName.getText().length() == 0)
    		{
                ad.setMessage("Please input [Name] ");
                ad.show();
                txtName.requestFocus();
                return false;
    		}
    		// Check Email
    		if(txtEmail.getText().length() == 0)
    		{
                ad.setMessage("Please input [Email] ");
                ad.show();
                txtEmail.requestFocus();
                return false;
    		}
      		// Check Tel
    		if(txtTel.getText().length() == 0)
    		{
                ad.setMessage("Please input [Tel] ");
                ad.show();
                txtTel.requestFocus();
                return false;
    		}