Java: Making sure a value is one of possible values

Question

I was hoping there is some way in java do to as the title says. For example:

int Num1 = 5;
int Num2 = 9;
char Char1 = 'a';
char Char2 = 'g';
char[] CharArray = {'1','2','3','4','5','6','7','8'
                    '9','a','b','c','d','e','f'}

I would like it to return true for Num1, Num2, and Char1, while Char2 should return false.

I know in MATLAB it's quite easy, you can simply just do:

ismember([Num1 Num2 Char1 Char2], CharArray)

This will return 1,1,1,0

how come true for Char1 but false for Char2?!!! – Kick Buttowski Oct 23 '14 at 23:11 — Kick Buttowski, Oct 23 '14 at 23:11

score 2 · Accepted Answer · answered Oct 23 '14 at 23:09

2

Does it have to be an array? If not, how about:

String allowedCharacters = "123456789abcdef";

allowedCharacters.contains("a"); // true
allowedCharacters.contains("g"); // false
allowedCharacters.contains(String.valueOf(5)); // true
allowedCharacters.contains(String.valueOf(-1)); // false

answered Oct 23 '14 at 23:09

jmrah

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also worth a mention that you can create a `String` object from a character array. `new String(CharArray)`. – ug_ Oct 23 '14 at 23:11
how come true for Char1 but false for Char2?!!! – Kick Buttowski Oct 23 '14 at 23:12

Jon Kiparsky · Answer 2 · 2014-10-23T23:17:13.273

As far as I know Java doesn't provide a method comparable to the MATLAB method you mention, but it shouldn't be too hard to implement - the Arrays.binarySearch method will be useful here.

If you don't mind having your charArray sorted along the way, you'd do something like

public boolean[] members(char[] needles, char[] haystack) {
  Arrays.sort(haystack);  // better to do this outside this method...
  boolean [] results = boolean[needles.length];
  for (int i = 0; i < needles.length; i ++) {
    results[i] = Arrays.binarySearch(haystack, needles[i]) >= 0;
  }
  return results;
}

(note: this code is not tested, and is just an illustration)

score 0 · Answer 3 · answered Oct 23 '14 at 23:21

0

Did you try with something like this?

public static boolean useList(String[] arr, String targetValue) { 
    return Arrays.asList(arr).contains(targetValue);
 }

answered Oct 23 '14 at 23:21

dccdany

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Java: Making sure a value is one of possible values

3 Answers3