E、T又是什么其它的含义呢?E ElementT or S TypeK Key, as in K, VV Value* T — Type* S — for T
<E>、<T>又是什么其它的含义呢? E Element T or S Type K Key, as in <K, V> V Value
* <T> — Type * <S> — for Type, when T is already in use * <E> — Element (used extensively by the Java Collections Framework) * <K> — Key * <V> — Value * <N> — Number