Iterating through array - java

Question

I was wondering if it was better to have a method for this and pass the Array to that method or to write it out every time I want to check if a number is in the array    For example   public static boolean inArray int   array  int check         for  int i   0  i  lt  array length  i              if  array i     check               return true             return false      Thanks for the help in advance

User · Answer

You can import the lib org apache commons lang ArrayUtils  There is a static method where you can pass in an int array and a value to check for   contains int   array  int valueToFind             Checks if the value is in the given array   ArrayUtils contains intArray  valueToFind     ArrayUtils API

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If you are using an array  and purely an array   the lookup of  contains  is O N   because worst case  you must iterate the entire array   Now if the array is sorted you can use a binary search  which reduces the search time to log N  with the overhead of the sort   If this is something that is invoked repeatedly  place it in a function     private boolean inArray int   array  int value           for  int i   0  i  lt  array length  i                   if  array i     value                         return true                       return false

User · Answer

Since atleast Java 1 5 0  Java 5  the code can be cleaned up a bit  Arrays and anything that implements Iterator  e g  Collections  can be looped as such   public static boolean inArray int   array  int check       for  int o   array         if  o    check             return true                  return false      In Java 8 you can also do something like      import java util stream IntStream   public static boolean inArray int   array  int check       return IntStream of array  anyMatch val - gt  val    check       Although converting to a stream for this is probably overkill

User · Answer

You should definitely encapsulate this logic into a method   There is no benefit to repeating identical code multiple times   Also  if you place the logic in a method and it changes  you only need to modify your code in one place   Whether or not you want to use a 3rd party library is an entirely different decision

User · Answer

Using java 8 Stream API could simplify your job   public static boolean inArray int   array  int check        return Stream of array  anyMatch i - gt  i    check       It s just you have the overhead of creating a new Stream from Array  but this gives exposure to use other Stream API  In your case you may not want to create new method for one-line operation  unless you wish to use this as utility  Hope this helps

[java] Iterating through array - java

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