Java determines whether an array contains an element

One: Use List

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

Two: Use Set

public static boolean useSet(String[] arr, String targetValue) {
  Set<String> set = new HashSet<String>(Arrays.asList(arr));
  return set.contains(targetValue);
}

Three: Use loop judgment

public static boolean useLoop(String[] arr, String targetValue) {
  for(String s: arr){
    if(s.equals(targetValue))
      return true;
  }
  return false;
}

Four: Use Arrays.binarySearch()

Arrays.binarySearch()The method can only be used for ordered arrays! ! ! If the array is unordered, the results will be strange.

The usage of finding whether an ordered array contains a certain value is as follows:

public static boolean useArraysBinarySearch(String[] arr, String targetValue) { 
  int a = Arrays.binarySearch(arr, targetValue);
  if(a > 0)
    return true;
  else
    return false;
}

Recommended tutorial: java quick start

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