Fill an array with random numbers

Question

I need to create an array using a constructor  add a method to print the array as a sequence and a method to fill the array with random numbers of the type double  Here s what I ve done so far  import java util Random   public class NumberList       private static double   anArray       public static double   list             return new double 10                  public static void print            System out println String join  quot   quot   anArray              public static double randomFill             return  new Random    nextInt                   public static void main String args                 TODO          I m struggling to figure out how to fill the array with the random numbers I have generated in the randomFill method  Thanks

User · Answer

Fast and Easy  double   anArray   new Random   doubles 10  toArray

User · Answer

Probably the cleanest way to do it in Java 8   private int   randomIntArray        Random rand   new Random       return IntStream range 0  23  map i - gt  rand nextInt    toArray

User · Answer

You could loop through the array and in each iteration call the randomFill method  Check it out  import java util Random   public class NumberList       private static double   anArray       public static double   list               return new double 10              public static void print             System out println String join  quot   quot   anArray                public static double randomFill             return  new Random    nextInt               public static void main String args              list            for int i   0  i  lt  anArray length  i                anArray i    randomFill             print

User · Answer

I tried to make this as simple as possible in Java  This makes an integer array of 100 variables and fill it with integers between 0 and 10 using only three lines of code  You can easily change the bounds of the random number too   int RandNumbers   new int 100   for  int i 0 i lt RandNumbers length i        RandNumbers i  ThreadLocalRandom current   nextInt 0 10

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People don t see the nice cool Stream producers all over the Java libs   public static double   list        return new Random   ints   asDoubleStream   toArray

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You can call the randomFill   method in a loop and fill your array in the main   method like this  public static void main String args          for  int i   0  i  lt  anArray length  i              anArray i    randomFill             You would then need to use rand nextDouble   in your randomFill   method the array to be filled is a double array  The below snippet should help you get random double values to be filled into your array  double randomDoubleValue   rand nextDouble    return randomDoubleValue

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If the randomness is controlled like this there can always generate any number of data points of a given range  If the random method in java is only used  we cannot guarantee that all the numbers will be unique    x000D   x000D  package edu iu common  x000D   x000D  import java util ArrayList  x000D  import java util Random  x000D   x000D  public class RandomCentroidLocator   x000D   x000D  public static void main String    args   x000D    x000D   int min  0  x000D   int max   10  x000D   int numCentroids   10  x000D   ArrayList lt Integer gt  values   randomCentroids min  max  numCentroids    x000D   for Integer i   values   x000D    System out print i       x000D     x000D    x000D    x000D   x000D  private static boolean unique ArrayList lt Integer gt  arr  int num  int numCentroids    x000D   x000D   boolean status   true  x000D   int count 0  x000D   for Integer i   arr   x000D    if i  num   x000D     count    x000D      x000D     x000D   if count  1   x000D    status   true  x000D    else if count gt 1   x000D    status  false  x000D     x000D    x000D   x000D   return status  x000D    x000D   x000D     generate random centroid Ids - gt  these Ids can be used to retrieve data x000D     from the data Points generated x000D     simply we are picking up random items from the data points x000D     in this case all the random numbers are unique x000D     it provides the necessary number of unique and random centroids x000D  private static ArrayList lt Integer gt  randomCentroids int min  int max  int numCentroids    x000D   x000D   Random random   new Random    x000D   ArrayList lt Integer gt  values   new ArrayList lt Integer gt     x000D   int num   -1  x000D   int count   0  x000D   do   x000D    num   random nextInt max - min   1    min  x000D    values add num   x000D    int index  values size  -1  x000D    if unique values  num  numCentroids        x000D     count    x000D     else  x000D     values remove index   x000D      x000D     x000D     while     count    numCentroids    x000D   x000D   return values  x000D   x000D    x000D   x000D    x000D   x000D   x000D

User · Answer

You can simply solve it with a for-loop  private static double   anArray   public static void main String args          anArray   new double 10      create the Array with 10 slots     Random rand   new Random       create a local variable for Random     for  int i   0  i  lt  10  i       create a loop that executes 10 times               anArray i    rand nextInt       each execution through the loop                                            generates a new random number and                                            stores it in the array at the                                            position i of the for-loop           printArray       print the result    private static void printArray         for  int i   0  i  lt  10  i              System out println anArray i              Next time  please use the search of this site  because this is a very common question on this site  and you can find a lot of solutions on google as well

User · Answer

You can use IntStream ints   or DoubleStream doubles   available as of java 8 in Random class  something like this will work  depends if you want double or ints etc    Random random   new Random     int   array   random ints 100000  10 100000  toArray      you can print the array and you ll get 100000 random integers

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This will give you an array with 50 random numbers and display the smallest number in the array  I did it for an assignment in my programming class   public static void main String args             TODO Auto-generated method stub      int i      int   array   new int 50       for i   0  i  lt   array length  i              array i     int  Math random     100           System out print array i                    int smallest   array 0            for  i 1  i lt array length  i                      if  array i  lt smallest          smallest   array i

User · Answer

This seems a little bit like homework  So I ll give you some hints  The good news is that you re almost there  You ve done most of the hard work already    Think about a construct that can help you iterate over the array  Is there some sort of construct  a loop perhaps   that you can use to iterate over each location in the array  Within this construct  for each iteration of the loop  you will assign the value returned by randomFill   to the current location of the array    Note  Your array is double  but you are returning ints from randomFill  So there s something you need to fix there

User · Answer

Try this  public void double randomFill         Random rand   new Random        for  int i   0  i  lt  this anArray length    i            this anArray i    rand nextInt

User · Answer

You need to add logic to assign random values to double   array using randomFill method   Change   public static double   list        anArray   new double 10          return anArray       To   public static double   list         anArray   new double 10       for int i 0 i lt anArray length i                  anArray i    randomFill              return anArray      Then you can call methods  including list   and print   in main method to generate random double values and print the double   array in console    public static void main String args       list    print         One result is as follows   -2 89783865E8  1 605018025E9  -1 55668528E9  -1 589135498E9  -6 33159518E8  -1 038278095E9  -4 2632203E8  1 310182951E9  1 350639892E9  6 7543543E7

[java] Fill an array with random numbers

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