CODEWITHSUNDEEP
javaarraysif-statement
Ricky
Ricky

Reputation: 125

Better alternative to long list of if statements

I have an int called dayCounter that runs 1 to 7. And i have a String called day. dayCounter increments every 10 seconds using TimerTask.

I use the following if statement inside the private void run() method used for TimerTask::

if (dayCounter == 1) {
    day = "Monday";
}

I have an if statement like this for every day of the week. Is there a more efficient way which gets the same result. I was thinking maybe creating an array with holds String month and then increment it some way. But i wouldn't know how to go about it. Any ideas?

Upvotes: 2

Views: 354

Answers (3)

Marvin
Marvin

Reputation: 14255

Probably the easiest way would be to use an array for the days:

public class Demo {

     public static void main(String[] args) {
        System.out.println(getDay(1));
        System.out.println(getDay(7));
     }

     // Returns the corresponding day for the given dayCounter.
     // Assumes that dayCounter goes from 1-7.
     private static String getDay(int dayCounter) {
         String[] days = new String[] { "Monday", "Tuesday", "Wednesday",
               "Thursday", "Friday", "Saturday", "Sunday" };
         return days[dayCounter - 1];
     }
}

If your counter goes above 7 (e.g. you are incrementing it by 1 in each timer step), you might want to be interested in this version, which basically loops through all available days:

public class Demo {

     public static void main(String[] args) {
        System.out.println(getDay(1));
        System.out.println(getDay(7));
        System.out.println(getDay(8));
        System.out.println(getDay(13));
     }

     // Returns the corresponding day for the given dayCounter.
     // Maps dayCounter to the range of 1-7, assumes that dayCounter
     // goes from 1-Integer.MAX_VALUE.
     private static String getDay(int dayCounter) {
         String[] days = new String[] { "Monday", "Tuesday", "Wednesday",
               "Thursday", "Friday", "Saturday", "Sunday" };
         return days[dayCounter % 7];
     }
}

Or you could use DateFormatSymbols to retrieve the weekdays and get them even (nearly) automatically translated for you:

import java.text.DateFormatSymbols;

public class Demo {

     public static void main(String[] args) {
        System.out.println(getDay(1));
        System.out.println(getDay(7));
     }

     // Returns the corresponding day for the given dayCounter.
     // Assumes that dayCounter goes from 1-7.
     private static String getDay(int dayCounter) {
        String[] days = DateFormatSymbols.getInstance().getWeekdays();
        return days[dayCounter];
     }
}

Or for Java 8 and later, the currently preferred way might be to make use of new java.time API (you can play around with the method arguments). This API includes a handy DayOfWeek enum.

import java.time.DayOfWeek;
import java.time.format.TextStyle;
import java.util.Locale;

public class Demo {

    public static void main(String[] args) {
        System.out.println(getDay(1));
        System.out.println(getDay(7));
    }

    // Returns the corresponding day for the given dayCounter.
    // Assumes that dayCounter goes from 1-7.
    private static String getDay(int dayCounter) {
        return DayOfWeek.of(dayCounter)
                 .getDisplayName(TextStyle.FULL, Locale.getDefault());
    }

}

And if you just want to replace the if statements, go with the switch-case as mentioned in Ryan's answer.

Upvotes: 3

scrayne
scrayne

Reputation: 718

You can have an array of strings, dayOfWeek, one for each day of the week. Then you use dayCounter as as index into the array. For example, if dayCounter = 1, then dayOfWeek[dayCounter] would be "Monday". This way you need only one statement to get the name of the day of the week.

Upvotes: 1

Ryan
Ryan

Reputation: 1974

Other then a if statement you can use a switch case with the counter

switch(dayCounter){
    case 1:
        day = "Monday";
        break;
    case 2: 
        day = "Tuesday";
        break;
}

Although this is another way to do it they both create the same byte code and the only difference between these two options is the readability of the code.

Upvotes: 4

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