Android, JAVA ไม่เข้าใจคำสั่งดังต่อไปนี้อ่ะคะ พอดีทำโปรเจ็คมาไม่เข้าใจคำสั่งนี้อ่ะคะ

if (a1.getText().length()==0)  ||  b1.getText().length()==0 || c1.getText().length()==0 || d1.getText().length()==0 || e1.getText().length()==0) {

return;
}

public boolean checkValid() {
    	
    	       alertShow = new AlertDialog.Builder(this);
    	       alertShow.setTitle("Sorry, Please check input.");
               alertShow.setPositiveButton("Close", null);
    
    	
    if (a1.getText().length()==0)  {

         alertShow.setMessage("Please, Check info.");
         alertShow.show();
         a1.requestFocus();
         return false;
     }

     common : but, change variable

}