Introduction to the method of java determining whether the specified element contains an array

How to check if an array (unordered) contains a specific value? This is a frequently used and very useful operation in Java. (Recommended: java video tutorial)

Let’s take a look at the method of determining whether an array contains a specified element in Java:

Check whether the array contains a certain element Methods for individual values

1. Use List

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

2. Use Set

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

3. Use loop judgment

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

4. Use Arrays.binarySearch()

The Arrays.binarySearch() 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;
}

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