CODEWITHSUNDEEP
javastring
PrimalScientist
PrimalScientist

Reputation: 861

What is the correct way to return a substring(n, m) within a method statement in Java?

I am going through previous exam questions and my question is what is the correct way or ways to determine a String length and return it.

If the String is less than 5 characters in length then I can return it the following way:

public static String first5(String s){
     if(s.length() < 5)
     return s;
}

If the String is greater than 5 characters though, it can be returned in the following way:

public static String first5(String s){

     return s.substring(0, 4);
}

What I must note is that when I answered this type of question before in an in class test, my lecturer stressed that I should not really use 'magic numbers'? I am not sure what he actually meant by that though.

Is there a better way to return this type of method at all?

I am still learning Java so please forgive any errors in my syntax.

Many thanks.

Upvotes: 0

Views: 367

Answers (4)

Franklin
Franklin

Reputation: 1801

Essentially if the requirements ever change, you can easily change the value in one location; thus, it will be changed everywhere it's referenced. You won't have to worry about any fragments of the old requirements floating around in the code. This is generally a good rule to follow with a large chunk of code.

public class solution {
    static final int VAR1 = 0;
    static final int VAR2 = 4;
    static final int VAR3 = 5;
    public static String first5(String s){
        if(s.length() < VAR3) { 
            return s;
        } else {
            return s.substring(VAR1, VAR2);
        }
    }
}

Of course the variable names will have to be named something meaningful to the class/application itself.

Upvotes: 1

Hot Licks
Hot Licks

Reputation: 47739

Note that there's no great shame in using an if statement:

String r = null;
if (s.length() < 5) {
    r = s;
}
else {
    r = s.substring(0,5);
}
return r;

The logic is clearer than if you use ?:. The advantage of the latter is that it occupies less screen real-estate, so you can get more of a large function onto a screen -- valuable if you have a large function, but counter-productive if not.

Upvotes: 1

David Mathias
David Mathias

Reputation: 335

Is the number 5 is in your question? If not get the number as input argument with the string input.

Upvotes: 0

Marko Topolnik
Marko Topolnik

Reputation: 200206

This should be your method first5:

public static String first5(String s){
  return s.length() < 5? s : s.substring(0, 5);
}

There are no magic numbers here, but maybe the teacher meant the number 5 was a magic number and wanted you to generalize the function:

public static String firstN(String s, int n){
  return s.length() < n? s : s.substring(0, n);
}

Upvotes: 3

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