Introduction to UUID in Java

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What are the contents of the UUID class in jdk, and what are some useful methods? ? ?

Solution

UUID: Universally Unique Identifier

UUID type:

Time-based UUID, DCE secure UUID, name-based UUID and random The corresponding version values ​​​​of the generated UUID are 1, 2, 3 and 4 respectively

Commonly used methods for UUID:

public static UUID randomUUID()

Get type 4 (pseudo Static factory for randomly generated UUIDs. Generate the UUID using a cryptographically strong pseudo-random number generator.

public static UUID fromString(String name)

Convert a uuid to a UUID class

public int compareTo(UUID val)

Compare this UUID with The specified UUID is compared.

If the two UUIDs are different, and the most significant field of the first UUID is greater than the corresponding field of the second UUID, then the first UUID is greater than the second UUID

[code]import java.util.UUID;

/**
 * Created by Ay on 2016/4/18.
 */
public class JavaUUIDTest {

    public static void main(String[] args) {

        //randomUUID方法
        String firstUuid = UUID.randomUUID().toString();
        System.out.println("firstUuid" + firstUuid);
        //fromString方法
        String secondUuid ="0c312388-5d09-4f44-b670-5461605f0b1e";
        String fromStringUuid = UUID.fromString(secondUuid).toString();

        //字符串转化为UUID类
        UUID uuid1 = UUID.fromString(firstUuid);
        //字符串转化为UUID类
        UUID uuid2 = UUID.fromString(secondUuid);

        int isEqules =  uuid1.compareTo(uuid2);

        System.out.println("uuid1 和 uuid是否相等:" + isEqules);
    }
}

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