Code Breaks After Upgrading To Java 8?

We recently upgraded to JDK 8. Since then, a section of code in a jsp file breaks. The code is this:

ArrayList all = new ArrayList();
final List tsd = timeSeriesBean.getTSData();
all.addAll(tsd); 
Collections.sort(all, new Comparator() {
public int compare(Object o1, Object o2) {
TSData t1 = (TSData)o1, t2 = (TSData)o2;
int res = t2.getDate().compareTo(t1.getDate());

[code]....

The error message is this:

An error occurred at line: 65 in the jsp file: /TS/VerifyImportTSData.jsp The type new Comparator(){} must implement the inherited abstract method Comparator.thenComparing(Function, Comparator)
 
64:
65: Collections.sort(all, new Comparator() {
66: public int compare(Object o1, Object o2) {
67: TSData t1 = (TSData)o1, t2 = (TSData)o2;
68: int res = t2.getDate().compareTo(t1.getDate());

just trying to maintain some old java code that I can support until it is rewritten.