Implementing the Insertion Sort Algorithm in Java

Insertion sort is a simple and intuitive sorting algorithm. Its core idea is to insert unsorted elements one by one into their correct positions in the sorted part, similar to organizing playing cards. It is suitable for small-scale data and has a simple implementation. Basic idea: Starting from the second element, mark the current element as the "element to be inserted". Compare it with the elements in the sorted part from back to front. If the sorted element is larger, shift it backward until the insertion position is found. Repeat this process until all elements are processed. In Java implementation, the element to be inserted needs to be saved, and the insertion is completed by looping through comparisons and shifting elements backward. The time complexity of the algorithm is: best O(n) (when already sorted), worst and average O(n²); space complexity O(1) (in-place sorting); stable sort, suitable for small-scale data or nearly sorted data. Its core lies in "gradual insertion", with simple implementation. Its stability and in-place nature make it perform well in small-scale sorting.