打印数组
1. Arrays.toString(arr)
2. for(int n: arr) System.out.println(n+", ");
3.for (int i = 0; i < arr.length; i++) {
System.out.print(arr[i] +", ");
}
4.System.out.println(Arrays.asList(arr));
5.Arrays.asList(arr).stream().forEach(s -> System.out.println(s));//java8
