没有引用的Java数组传递

Question

我试图在不使用引用的情况下传递数组，而是直接使用值:

    public static void main(String[] args){
            int[] result = insertionSort({10,3,4,12,2});
    }

    public static int[] insertionSort(int[] arr){
        return arr;
    }

但它返回以下异常:

Exception in thread "main" java.lang.Error: Unresolved compilation problems: 
Syntax error on token(s), misplaced construct(s)
Syntax error on token ")", delete this token

当我尝试下面的代码时，它起作用了，任何人都可以解释原因吗？

    public static void main(String[] args){
        int[] arr = {10,3,4,12,2};
        int[] result = insertionSort(arr);  
    }

    public static int[] insertionSort(int[] arr){
        return arr;
    }

Answer 1

必须是

int[] result = insertionSort(new int[]{10,3,4,12,2});

{10,3,4,12,2} 是数组初始化的语法糖，必须和下面的声明语句一起使用-

int[] arr = {10,3,4,12,2};

下面的东西也是不允许的-

int[] arr; // already declared here but not initialized yet
arr = {10,3,4,12,2}; // not a declaration statement so not allowed