如何替换超过 16 个 if else-if 语句 Java

Question

Im trying to make a program that allows the client to input a String. The string length should have 3 characters only and should contain the letters .

My program have to pass through this table and check what this string refers to..

Let's say the client passed this String "AUG", my program should show the name of this String which is "Met".

I made a code, and it worked but it has more then 15 if else-if condition.

My question is : Is there any other way to do it without using if else-if (or switch). And does polymorphism work in this case ?

Answer 1

Have a look at HashMap

You can build your table with:

Map<String, String> table = new HashMap<>();
table.put("AUG", "Met");
table.put(...);

Then access your table using the user's input:

if(table.containsKey(input)){
    return table.get(input);
}

Answer 2

I think I'd go about it with an enum personally (provided performance wasn't a significant concern):

public enum Abbreviations {
    Ala("GCU", "GCC", "GCA", "GCG"),
    Arg("CGU", "CGC", "CGA", "CGG", "AGA", "AGG")
    // ...
    ;

    private final List<String> codons;

    private Abbreviations(final String... codons) {
        this.codons = Arrays.asList(codons);
    }


    public boolean contains(final String codon) {
        return this.codons.contains(codon);
    }
}

And then you can find their matching from the String using something like:

public String find(final String codon) {
    for (final Abbreviations abb : Abbreviations.values()) {
        if (abb.contains(codon)) {
            return abb.name();
        }
    }

    throw new IllegalArgumentException("Unknown codon: '" + codon + "'");
}

Answer 3

You could try an Object Oriented Aproach:

//This is your representation of Codon
//Which has a name e.g. Alanine and an Abreviation object.
public class Codon {

        private String name;

        private Abreviation abreviation;

        public Codon(String name, Abreviation abreviation) {

            this.name = name;
            this.abreviation = abreviation;
            this.abreviation.addCodon(this);

        }

        @Override
        public String toString() {
            return "Codon [name=" + name + ", abreviation=" + abreviation + "]";
        }


    }

import java.util.ArrayList;
import java.util.List;
// This is a representation of an abreviation object
// Which has an abreviation: ALA;
// and the name of the abreviation "Alanine".
public class Abreviation {

    private String abreviation;
    private String name;
    private List<Codon> codons = new ArrayList<>();

    public Abreviation(String abreviation, String name) {
        super();
        this.abreviation = abreviation;
        this.name = name;

    }

    public boolean addCodon(Codon codon) {
        return this.codons.add(codon);
    }

    @Override
    public String toString() {
        return "Abreviation [abreviation=" + abreviation + ", name=" + name + "]";
    }

}


// Here is your program, where it's being build all the Codons structure with your respective Abbreviation.
public class App {

    public static void main(String[] args) {
        // This is abreviation, it'll will associated with the codon 
        Abreviation alanine = new Abreviation("Ala", "Alanine");
        // Here it's being build the codon CGU, which has abreviation alanine
        Codon GCU = new Codon("GCU", alanine);
        // Then using toString method it prints what have been done 
        System.out.println(GCU);

    }

}

You can put all of your codons into a List, so you can search and retrieve then.