HashMap pair.getValue在返回Array，Java时返回ArrayList

Question

我有以下HashMap：

Map<String, String[]> aMap = new HashMap<String, String[]>()

以及具有以下签名的方法：

private boolean verifyFileName(String fileName, String[] allowableValues)

我调用这样的方法：

Map.Entry<String, String[]> pair = (Map.Entry)it.next();

...

verifyFileName(file.getName(), pair.getValue())

问题是verifyFileName抛出一个错误，说它的第二个参数是ArrayList。当我将verifyFileName的签名更改为(String fileName, ArrayList<String> allowableValues)时，错误消失。

这里发生了什么？

编辑：这是我使用HashMap的JUnit测试（用Groovy编写）：

   @Test
    public void verifyGeneratedAndCompiledFiles() { 
        Iterator it = DIRECTORIES_TO_CHECK.entrySet().iterator();
        while (it.hasNext()) {
            Map.Entry<String, String[]> pair = it.next();
            int count = 0
            File createdFolder = new File(pair.getKey())
            for (File file: createdFolder.listFiles()) {
               println('checking for ' + file.getName())               
                if (file.length() == 0) {
                    fail(createdFolder.getPath() + ' folder contains an empty file')
                }

                if (!verifyFileName(file.getName(), pair.getValue())) {
                    fail(createdFolder.getPath() + ' folder is missing ' + file.getName())
                }
                count++
            }

            if (count != 2) {
                fail(createdFolder.getName() + " folder contains an incorrect number of files")
            }

            count = 0
        }       
    }

以及我在此声明和初始化DIRECTORIES_TO_CHECK：

  private static final Map<String, String[]> DIRECTORIES_TO_CHECK
    static {
        Map<String, String[]> aMap = new HashMap<String, String[]>()
        aMap.put(DIRECTORIES_ROOT + "subproj/build/classes/generatedSource", ["Subproj.class", "Subproj2.class"])
        aMap.put(DIRECTORIES_ROOT + "sub2/build/classes/generatedSource", ["Sub2.class", "Sub22.class"])
        aMap.put(DIRECTORIES_ROOT + "subproj/generated/java", ["Subproj.java, Subproj2.java"])
        aMap.put(DIRECTORIES_ROOT + "sub2/generated/java", ["Sub2.java", "Sub22.java"])
        DIRECTORIES_TO_CHECK = Collections.unmodifiableMap(aMap)
    }