I'm trying to figure out the best way to search a customer in an ArrayList by its Id number. The code below is not working; the compiler tells me that I am missing a return statement.

Customer findCustomerByid(int id){

boolean exist=false;

if(this.customers.isEmpty()) {

return null;

}

for(int i=0;i

if(this.customers.get(i).getId() == id) {

exist=true;

break;

}

if(exist) {

return this.customers.get(id);

} else {

return this.customers.get(id);

}

}

}

//the customer class is something like that

public class Customer {

//attributes

int id;

int tel;

String fname;

String lname;

String resgistrationDate;

}

解决方案

The compiler is complaining because you currently have the 'if(exist)' block inside of your for loop. It needs to be outside of it.

for(int i=0;i

if(this.customers.get(i).getId() == id){

exist=true;

break;

}

}

if(exist) {

return this.customers.get(id);

} else {

return this.customers.get(id);

}

That being said, there are better ways to perform this search. Personally, if I were using an ArrayList, my solution would look like the one that Jon Skeet has posted.