How to write quick sort in java

Java's quick sort usually adopts the idea of ​​divide and conquer, and the specific steps are as follows: 1. Select a reference element from the array; 2. Put all elements smaller than the reference value in front of the reference, and all elements smaller than the reference value Larger elements are placed behind the benchmark (the same number can go to either side); 3. For the two subsets on the left and right of the benchmark, repeat the first and second steps until all subsets have only one element left .