Collection, a tool class of Java operation collection

Collections is a tool class that operates on collections such as set, list, and map.

Collections provides a large number of methods to sort, query and modify collection elements. It also provides methods to set immutable collection objects and realize synchronous control over collection objects.

Sort operation:

Output:

Original LIST1: [2,1,4,3] reverse LIST1: [3,2] sort LIST1: [1,2,3,4] disrupt LIST1: [1,4] sort by age in descending order: name = Bob, age = 32, name = Tom, age = 21, name = jack, age = 16

Find and replace operations:

Output:

[2,1] 4 1 2 true [2,2] name=tom,age=16 name=bob,age=32 bob/32 jack/16

Synchronization control: multiple synchronizedxxx () methods are provided in collections, which can wrap the specified collection into a thread synchronized collection, so as to solve the thread safety problem when multiple threads access the collection concurrently.