How to determine whether a certain value exists in a string array in java

Method 1:

You can use the binarySearch(Object[] a, Object key) method in the Arrays class to Finds whether a certain value exists. If a certain value exists, the return value is greater than 0, otherwise the return value is less than 0.

Advantages: Use binary search method, fast and efficient.

Disadvantages: The queried array must be ordered. If it is not ordered, using this method is useless.

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Example:

String[] array = {"1","2","3","4"};
int index = Arryas.binarySearch(array,"2");
System.out.println("index:" + index); //--- index:1
index = Arryas.binarySearch(array,"0");
System.out.println("index:" + index); //--- index:-1
index = Arryas.binarySearch(array,"5");
System.out.println("index:" + index); //--- index:-5

Method 2:

Use ArraysThe asList() method in the class converts the array into a List() list, and then uses the contains() method to determine whether a certain value exists in the array.

Advantages: Arrays can be out of order and there is no order requirement.

Disadvantages: The query efficiency may be slightly slower, but it should not affect the overall situation.

Example:

String[] array = {"1","2","3","4"};
boolean flag = Arrays.asList(array).contains("2");
System.out.println("flag:" + flag);//--- flag:true
flag = Arrays.asList(array).contains("0");
System.out.println("flag:" + flag);//--- flag:false
flag = Arrays.asList(array).contains("5");
System.out.println("flag:" + flag);//--- flag:false

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