java how to time algorithm code example

Example 1: java execution time

long start = System.currentTimeMillis();
class.method();
long time = System.currentTimeMillis() - start;

Example 2: java get excectuon time

long startTime = System.nanoTime();
methodToTime();
long endTime = System.nanoTime();

long duration = (endTime - startTime);  //divide by 1000000 to get milliseconds.