Long list of if statements in Java

by

using Command pattern:

public interface Command {
     void exec();
}

public class CommandA() implements Command {

     void exec() {
          // ... 
     }
}

// etc etc

then build a Map<String,Command> object and populate it with Command instances:

commandMap.put("A", new CommandA());
commandMap.put("B", new CommandB());

then you can replace your if/else if chain with:

commandMap.get(value).exec();

EDIT

you can also add special commands such as UnknownCommand or NullCommand, but you need a CommandMap that handles these corner cases in order to minimize client’s checks.

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