IntStream mapToInt(ToIntFunction<? super T> mapper);
LongStream mapToLong(ToLongFunction<? super T> mapper);
DoubleStream mapToDouble(ToDoubleFunction<? super T> mapper)
以上方法截自java8源码:package java.util.stream;
public class Demo {
public static void main(String[] args) {
List<String> stringList = new ArrayList<>();
stringList.add("1");
stringList.add("5");
stringList.add("3");
stringList.add("2");
int sum = stringList.stream().mapToInt(Integer::parseInt).sum();
System.out.println("sum = " + sum); // 控制台输出 sum = 11
}
}