W7R Tech: 20 Java Math.random() Uses

In this post, I have coded 20 Math.random manipulations in Java for you to access such as recieving a random card out of a deck of 64, selecting a random color (aprx. million colors), and some more simple applications like generating a percent (0% to 100%). Enjoy!

Positive Integers (1 to 10)

int result1 = (int)(Math.random()*10)+1;

Negative Integers (-1 to -10)

int result2 = (int)((Math.random()*(-10))-1);

Positive Integers (1 to 100)

int result3 = (int)(Math.random()*100)+1;

Percent Values (0.00% to 100.00%)
```
double result4 = (Math.random()*100); 
```

One or Zero / Bit Value

int result5 = ((int)(Math.random()*2));

Positive Odd Integers (1,3,5,7,9)

int result6 = ((int)(Math.random()*9)+1); 
 while(result6%2!=1){ 
  result6 = ((int)(Math.random()*9)+1); 
 }

Positive Even Integers (2,4,6,8,10)

int result = ((int)(Math.random()*10)+1); 
 while(result%2!=0){ 
  result = ((int)(Math.random()*10)+1); 
 }

Positive Multiples of Three (3,6,9,12,15,18, ... 54,57,60)
```
int result = ((int)(Math.random()*10+1))*3; 
```

Positive Multiples Of Four (4,8,12,16,20... 52,56,60)

int result = (((int)(Math.random()*10))+1)*4; 
System.out.println("mult of 4: "+result);

Perfect Squares (1,4,16,25,36,49,64,81,100,121)

int result = (int)Math.pow(((int)(Math.random()*11)+1),2); 
System.out.println("random perfect square: "+result);

Prime Numbers (1,3,5,7,11,13,17,19,23)

int[] primes= {2,3,5,7,11,13,17,19,23}; 
int randPrime = primes[(int)(Math.random()*primes.length)]; 
System.out.println("random prime: "+randPrime);

Specific Set of Integers

int[] possibleInts = {911,18,1,923,817,200}; 
int result = possibleInts[(int)(Math.random()*possibleInts.length)];

Specific Set of Strings

String[] strings = 
{"mango","pineapple", "orange", "apple", "banana", "kiwi"};
String result = strings[(int)(Math.random()*strings.length)];

Multiples of N (some integer N)

public int randomMultipleOf(int N, int greatestFactor){ 
return ((int)((Math.random()*greatestFactor)+1))*N; 
//highest return value = N*greatestFactor 
//in this example below it would be 7*9 = 63 maximum return value 
randomMultipleOf(7,9);

Random year of the last 100 years

int currentYear=2012;
int result = currentYear + ((int)(Math.random()*100)+1);

Random Color (RGB)

public Color randomColor(){ 
  return new Color((int)(Math.random()*256), (int)(Math.random()*256),(int)(Math.random()*256)); 
 }

Perfect Cubes

public int randomPerfectCube(int minRoot, int maxRoot){ 
  return ((int)(Math.random()*maxRoot)+minRoot); 
 }

Random Card of a Standard Card Deck

public String randomCard() { 
  int randSuit = (int)(Math.random()*4); 
  int randNumber =  (int)(Math.random()*14); 
  String suit, name; 
  if(randSuit==0) { 
   suit="Spades"; 
  } else if(randSuit==1) { 
   suit="Diamonds"; 
  } else if(randSuit==2) { 
   suit="Clubs"; 
  } else { 
   suit="Hearts"; 
  } 
  if((randNumber0)) { 
   name=randNumber+""; 
  } else if(randNumber==0) { 
   name="Ace"; 
  } else if(randNumber==11) { 
   name="Jack"; 
  } else if(randNumber==12) { 
   name="Queen"; 
  } else { 
   name="King"; 
  } 
  return name + " of  " + suit; 
}

Letters of the English Alphabet

public char randomLetter(){ 
   String letters = "abcdefghijklmnopqrstuvwxyz"; 
   return letters.charAt((int)(Math.random()*letters.length())); 
}

Letter from a specific String parameter

public char randomCharOf(String s) { 
     return s.charAt((int)(Math.random()*s.length())); 
 }

Contacting Brian:
If there are any errors at all or if you want to suggest or request another manipulation email me at w7rdotblogspot@gmail.com or simply comment on this post.

W7R Tech

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Sunday, April 08, 2012

20 Java Math.random() Uses