CODEWITHSUNDEEP
javaif-statementfor-loopoptimizationarraylist
haja
haja

Reputation: 135

Java for and if loop code optimisation

I have an ArrayList<String> and I need to loop through it, and what is present in the list has to perform certain actions. I wish to optimize the iteration and comparisons, can it be done?

My code:

Person class (includes getters and setters):

private String employeeID;

private String firstName;

private String lastName;

private String gender;

private String mobileNo;

private String emailID;

My computed ArrayList, myList- [firstName, gender, mobileNo, emailID]. How do I optimize my logic shown below to avoid so many if conditions?

Person p =new Person ();
for(String element:myList)
        {
       if("employeeid".equalsIgnoreCase(element))
            {
                p.setemployeeID("");
            }
       if("firstname".equalsIgnoreCase(element))
            {
                p.setfirstName("");
            }
       if("lastName".equalsIgnoreCase(element))
            {
                p.setlastName("");
            }
       if("gender".equalsIgnoreCase(element))
            {
                p.setgender("");
            }
       if("mobileno".equalsIgnoreCase(element))
            {
                p.setMobileNo("");
            }
       if("emailid".equalsIgnoreCase(element))
            {
                p.setEmailID("");
            }
        }

Upvotes: 1

Views: 84

Answers (3)

Idos
Idos

Reputation: 15310

There isn't so much to be done here, but maybe a switch can be more aesthetically pleasing. Though you will have to make sure your input is either only lowercase or only uppercase:

for(String element:myList) {
    switch (element.toLowerCase()){
        case "employeeid": p.setemployeeID(""); break;
        case "firstname" : p.setfirstname(""); break;
        .
        .
        .

    }
}

If you decide you wish to keep your if design, you should definitely use if-else so you won't have to run through all your ifs in every iteration.

And as a final note, this probably isn't the best way to design whatever it is you are trying to do. You should consider something of a more OO nature, like passing the parameters of a Person object to the constructor when you instantiate a Person object.

Edit: I see you want to use an Enum, you would want to actually define it like so:

public enum MyEnum {
    EMPLOYEE_ID("employeeid"),
    FIRST_NAME("firstname")
    .
    .
    .
    ;

    private final String text;

    private MyEnum(final String text) {
        this.text = text;
    }

    @Override
    public String toString() {
        return text;
    }
}

Upvotes: 3

Willian Dallastella
Willian Dallastella

Reputation: 36

I didn´t test, but (if the string and the method name are the same) you could use reflection, something like this:

Person p = new Person();
for(String element : myList) {

    // method params
    Class[] paramTypes = new Class[1];
    paramTypes[0] = String.class;

    // method
    String methodName = "set" + element.indexOf(0,1).toUpperCase() + element.indexOf(1);
    Method m = c.getDeclaredMethod(methodName, paramTypes);

    // call method
    m.invoke(p, "");
}

Upvotes: 0

Vaibhav Sharma
Vaibhav Sharma

Reputation: 2319

The compiler is able to optimize switch statements into a lookup table and perform compile-time checking for literals when dealing with enumerations. That being said, you should always use switch statements for over 3 comparisons. Hence your code becomes-

private static final String EMPLOYEE_ID = "employeeid";
private static final String FIRST_NAME = "firstname";
private static final String LAST_NAME = "lastName";
private static final String GENDER = "gender";
private static final String MOBILE_NO = "mobileno";
private static final String EMAIL_ID = "emailid";

Person p =new Person ();
for(String element: myList) {
switch (element.toLowerCase()) {
  case EMPLOYEE_ID: p.setemployeeID("");
    break;
  case FIRST_NAME: p.setfirstName("");
    break;
  case LAST_NAME: p.setlastName("");
    break;
  case GENDER: p.setgender("");
    break;
  case MOBILE_NO: p.setMobileNo("");
    break;
  case EMAIL_ID: p.setEmailID("");
    break;
}

}

Upvotes: 3

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