Java Stream 常用数组类型转换用法

业务目前经常会使用的stream流来处理数据，特别是对数组的类型进行转换，下面我分类总结常用的转换用法

 1.字符串数组 --》 数值型数组 int、Long、Double

String[] str = new String[]{"1","2","3","4","5","6"};
int[] ints = Arrays.stream(str).mapToInt(Integer::valueOf).toArray();
long[] longs = Arrays.stream(str).mapToLong(Long::valueOf).toArray();
double[] doubles = Arrays.stream(str).mapToDouble(Double::valueOf).toArray();

延伸一点，一般我们String数组元素是数字内容才需要转数值型，则可以通过sum函数进行求和

int sums = Arrays.stream(str).mapToInt(Integer::valueOf).sum();

2.字符串数组 --》List<Integer> 、List<Long>、List<Double>

String[] str = new String[]{"1","2","3","4","5","6"};
List<Integ