How to refactor this method?

public String getFirstOrLastNameOrBoth() {
    if (this.getFirstname() != null && this.getLastname() != null) {
        return this.getFirstname()   this.getLastname();
    } else if (this.getFirstname() != null && this.getLastname() == null){
        return this.getFirstname();
    } else if (this.getLastname() != null && this.getFirstname() == null){
        return this.getLastname();
    }
    return 0.0;
}

CodePudding user response：

    public String getFirstOrLastNameOrBoth() {
        return (getFirstname() == null ? "" : getFirstname()) 
               (getLastname() == null ? "" : getLastname());
    }

CodePudding user response：

There's no need to invoke getter in the class in order to access a field. Use the field name instead.

Instead of null-checks, you can make use of noneNullOrElse() static method of the Objects utility class.

return Objects.requireNonNullElse(firstName, "")  
       Objects.requireNonNullElse(lastName, "");

CodePudding user response：

public String getFirstOrLastNameOrBoth() {
    if(this.getFirstname() == null && this.getLastname() == null) {
        return "0.0";
    }
    
    return (this.getFirstName() != null ? this.getFirstName() : "")  
            (this.getLastname() != null ? this.getLastname() : "");
}

CodePudding user response：

if (this.getFirstname() != null && this.getLastname() != null) {
   return this.getFirstname()   this.getLastname();
} else {
   return Optional.ofNullable(this.getFirstname()).orElseGet(() -> Optional.ofNullable(this.getLastname()).orElseGet(() -> "0.0"));
}

CodePudding user response：

1. Don't use this if it is not necessary.
2. Use library methods to work with strings.

StringUtils.trimToEmpty() from Apache Commons org.apache.commons.lang3 can be used here

    public String getFirstOrLastNameOrBoth() {
        return trimToEmpty(getFirstname())   trimToEmpty(getLastname());
    }

CodePudding user response：

Another thing you can do is to transfer the if statements in the get methods, so you can check there whether something is null or not. More specifically:

 public String getFirstname() {
    if (firstname != null){
    return firstname;}

    return "";
}

public String getLastname() {
    if (lastname!= null){
        return lastname;}

    return "";
}
public String getFirstOrLastNameOrBoth() {
   return (getFirstname()   " "   getLastname()).trim();
}

This way is called the extract method and in this case, you'll be able to check for null not only in the last method but also in the getters. Therefore I think it is safe. I have also used the trim method in order to remove the spaces in the beginning in case the first name is null.