int sum = list2.stream().mapToInt(Integer::parseInt).sum();System.out.println(sum);
reduce加减乘除,获取最大值最小值
//获取三个值的乘值30Integer sum =Stream.of(1,3,10).reduce(1,(x, y)->{System.out.println("x="+ x +"y="+ y);return x * y;});System.out.println(sum);//获取最大值10Integer max =Stream.of(1,3,10).reduce(1,(x, y)->{System.out.println("x="+ x +"y="+ y);return x > y ? x : y;});System.out.println(max);//对象的年龄最大值Integer maxAge =Stream.of(newPerson("张三",18),newPerson("张三",19),newPerson("张三",12),newPerson("张三",10)).map(Person::getAge)//获取person的age值.reduce(0,Integer::max);//类型转化System.out.println(maxAge);