[OCPJP]遞迴刪除檔案

Given the code fragment:

public void recDelete(String dirName) throws IOException {
    File[] listOfFiles = new File(dirName).listFiles();
    if (listOfFiles != null && listOfFiles.length > 0) {
        for (File aFile : listOfFiles) {
            if (aFile.isDirectory()) {
                recDelete(aFile.getAbsolutePath());
            } else if (aFile.getName().endsWith(".class")) {
                aFile.delete();
            }
        }
    }
}

Assume that Projects contains subdirectories that contain .class files and is passed as an argument to the recDelete() method when it is invoked.

What is the result?

A. The method deletes all the .class files in the Projects directory and its subdirectories.
B. The method deletes the .class files of the Projects directory only.
C. The method executes and does not make any changes to the Projects directory.
D. The method throws an IOException.

題解

程式第16行，會找出dirName這個目錄下的所有檔案(不包括子目錄中的檔案)。程式第18行的for迴圈，會走訪所有檔案。若檔案為目錄，則再用這個目錄遞迴呼叫recDelete方法；若檔案不是目錄，且檔名是「.class」結尾的話，則刪除之。

所以答案是選項A。