String array in java random

Question

String [] rnum = {"Black", "Red", "Black", "Red", "Black", "Red", "Black","Red",
"Black", "Red", "Black", "Red", "Black", "Red", "Black", "Red","Black", "Red", "Green"}; 
int A = rnum.length; 
//the "Math.random() method will get you a random color

int random = (int) (Math.random() * A);  
//randomize the strings  
String Color = rnum[random];

How do i say "if color = black then do this" or same for green or same for red"

You could use an enum for this. But if you don't want to use an enum, you'll find that this is one of the very rare cases when it's OK to use == instead of .equals to compare Strings. — Dawood ibn Kareem
– Dawood ibn Kareem, Commented Apr 2, 2014 at 0:03
I agree with David Wallace, Enum is still the nicest way, also witching with enums is possible(before java 7) and if some color is added to use case, not much work to refactor the code. — chillworld
– chillworld, Commented Apr 2, 2014 at 2:26

ug_ · Accepted Answer · 2014-04-30 08:49:25Z

5

You mean...

if(Color.equals("Black")) {
   // then do this
} else if(Color.equals("Red"){
   // then do this
}

or even (In Java >= 1.7)

switch(Color) {
   case "Black":
       // then do this
       break;
   case "Red":
       // then do this
       break;
}

edited Apr 30, 2014 at 8:49

answered Apr 1, 2014 at 23:55

ug_

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1 Comment

chillworld Over a year ago

Take attention that switch with Strings is possible from java 7. Older versions do not support this.

geoff · Accepted Answer · 2014-04-01 23:55:46Z

0

Color should not be capitalized, since that can be a Java class name.

For this purpose you can use a ternary operator (shortened if-else):

String color = ( rnum[random].compareTo("Black") == 0 ? ** do something here ** : ** do something if the color is not "Black" ** );

or:

String color = "";
if(rnum[random].compareTo("Black") == 0) {
    // do stuff
}
else {
    // it's not black. do other stuff.
}

With red and green, just replace "Black" with "Red", or "Green".

answered Apr 1, 2014 at 23:55

geoff

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chillworld · Accepted Answer · 2014-04-02 02:20:16Z

0

Using java equals method for each color is the simplest way.

http://docs.oracle.com/javase/7/docs/api/java/lang/String.html#equals%28java.lang.Object%29

edited Apr 2, 2014 at 2:20

chillworld

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answered Apr 2, 2014 at 1:58

Jack Daniels

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Comments

CsBalazsHungary · Accepted Answer · 2014-04-30 09:36:05Z

0

Others said the method to decide equality, I would add up something about the algorithm.

Consider adding weight of colours, I see Red and Black appear 9 times while Green appears once. I would add an object containing the name of the colour and the weight you want to apply. Like {"Green", 1}, {"Red", 9}, {"Black", 9}.

Sum up the weights and order the colours in some way and decide where the random number fell.

It would make more clean code and nicer solution.

answered Apr 30, 2014 at 9:36

CsBalazsHungary

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