getting the index of a string in a string array

Question

My array looks something like this

String[] dayNames = new String[DAYS_IN_WEEK];
    dayNames[0] = "Sunday";
    dayNames[1] = "Monday";
    dayNames[2] = "Tuesday";
    dayNames[3] = "Wednesday";
    dayNames[4] = "Thursday";
    dayNames[5] = "Friday";
    dayNames[6] = "Saturday";

I need to print the index of the array using a method findDay.

so if "Saturday" was selected, i would need 6 to be returned.

Thanks for your time =D P.s. No answers please? Just suggestions =)

UPPDATE**

my array will not compile. This is exactly what i have:

private static final int DAYS_IN_WEEK = 7;
    String[] dayNames;
    dayNames = new String[DAYS_IN_WEEK]
    // Declare an array of Strings named dayNames
    dayNames[0] = "Sunday";
    dayNames[1] = "Monday";
    dayNames[2] = "Tuesday";
    dayNames[3] = "Wednesday";
    dayNames[4] = "Thursday";
    dayNames[5] = "Friday";
    dayNames[6] = "Saturday";

and I get multiple errors starting with:

Weekdays.java:12: error: <identifier> expected
    dayNames = new String[DAYS_IN_WEEK]

I don't understand why. I literally copied the EXACT format from http://docs.oracle.com/javase/tutorial/java/nutsandbolts/arrays.html

Do you mean "Saturday" and "6"? Or maybe "Sunday" and "0"? Also, have you learned about for loops? If yes, then try to come up with a solution using a for loop. If not, go learn it :) — jonathanasdf
– jonathanasdf, Commented Dec 1, 2012 at 3:06
@jonathanasdf I meant "Saturday" and 6 lol fail... and yes I have gone over for loops, will defiantly look over my notes! Thanks!! — WannaBeDroidProgrammer
– WannaBeDroidProgrammer, Commented Dec 1, 2012 at 3:13
@WannaBeDroidProgrammer Yep that would be the best idea. The answers below are all correct but I think would be a bit advanced for now. Once you have figured out how to solve the problem with a for loop though, I suggest you take a look at xagyg's solution with indexOf. I would recommend against looking at sdasdadas's enum solution at this point though, it will just be needlessly confusing. — jonathanasdf
– jonathanasdf, Commented Dec 2, 2012 at 2:11

xagyg · Accepted Answer · 2012-12-01 03:20:04Z

2

You could do this...

int index = Arrays.asList(dayNames).indexOf("Saturday");

I'll leave printing the index value as an exercise for you.

answered Dec 1, 2012 at 3:20

xagyg

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someone · Accepted Answer · 2012-12-01 03:08:16Z

1

Use a map your key is day and value is index.

Key => Sunday , Monday , Tuesday .....

Value = > 0,1,2 ..

Map the value against the key you required.

answered Dec 1, 2012 at 3:08

someone

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Comments

sdasdadas · Accepted Answer · 2012-12-01 03:14:53Z

Well, one way to do it would be like this:

public int findDay(String dayString) {
    if (dayString.equals("Sunday") {
        return 0;
    }
    else if (dayString.equals("Monday") {
    ...

You get the gist of it - but that's a fairly crufty solution.

An alternative would be to use Java's enumerated values:

public enum Day {
    SUNDAY(0), MONDAY(1), TUESDAY(2), WEDNESDAY(3) ...

    private final int i;
    private Day(int value) {
        i = value;
    }

    public int getNumericRepresentation() {
        return i;
    }
}

Then you can actually have an array of enumerations, like:

Day[] days = new Day[Day.values().size()];
int i = 0;
for (Day day : Day.values()) {
    days[i] = day;
    i++;
}

And to print out a day's numeric representation you just use:

day.getNumericRepresentation();

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