You'll find that these sorting methods look somewhat different from those in the book. That's because we're working in a different context. In the book, the methods sort external arrays which are passed as parameters. In these notes, the methods sort arrays that are part of the same class. In place sorting is a special subclass of sorting algorithms in which the original object is modified, and little, if any, extra storage is used.
Stable sorts preserve the order of equal elements.
Stable sorting is necessary if you want to sort the same list multiple times, on different keys. For large enough data sets, not all of the elements can be stored in memory. Often, variant algorithms must be used in order to get more efficient operation. You may learn about such sorting algorithms in CSC302. Most often, in-memory sorting is accomplished by repeatedly swapping elements.