在Java中使用递归填充Arraylist

Question

我试图用getMyClassTypes()的递归调用填充列表myClassTypes.但是每次有对该方法的递归调用时它都会被初始化.而且,由于这个原因,我失去了很少的价值.我理解问题是在本地声明:List myClassTypes = new ArrayList <>(); 但是,我不想在类级别声明列表.这是我正在使用的代码:

private List<MyClassType> getMyClassTypes(final String path) throws SVNException {

    final Collection<SVNDirEntry> svnDirectoryEntries = svnRepository.getDir(path, -1, null, (Collection<SVNDirEntry>) null);
    final Iterator<SVNDirEntry> svnDirectoryEntryIterator = svnDirectoryEntries.iterator();
    final List<MyClassType> myClassTypes = new ArrayList<>();

    while (svnDirectoryEntryIterator.hasNext()) {
        final SVNDirEntry entry = svnDirectoryEntryIterator.next();
        final String fileName = entry.getName();

        if (!path.isEmpty() && path.matches(SUB_DIRECTORY_NAME_PATTERN) && fileName.endsWith(".xml")) {                
            final MyClassType myClassType = new MyClassType(path, fileName);
            myClassTypes.add(myClassType);
        }

        /*
         * Check if the entry is a directory recursively.
         */
        if (someCondition) {
            getMyClassTypes((path.equals("")) ? entry.getName() : path + "/" + entry.getName());
        }
    }
    return myClassTypes;
}

即使在"n次"递归调用之后,如何管理'myClassTypes'以包含所有值？

Answer 1

将List<MyClassType>实例作为参数传递给方法,而不是在方法内创建它.

这种方式只创建一个ArrayList实例,甚至可以将返回类型更改为void.

private void getMyClassTypes(final String path, List<MyClassType> myClassTypes) throws SVNException 
{
    final Collection<SVNDirEntry> svnDirectoryEntries = svnRepository.getDir(path, -1, null, (Collection<SVNDirEntry>) null);
    final Iterator<SVNDirEntry> svnDirectoryEntryIterator = svnDirectoryEntries.iterator();

    while (svnDirectoryEntryIterator.hasNext()) {
        final SVNDirEntry entry = svnDirectoryEntryIterator.next();
        final String fileName = entry.getName();

        if (!path.isEmpty() && path.matches(SUB_DIRECTORY_NAME_PATTERN) && fileName.endsWith(".xml")) {                
            final MyClassType myClassType = new MyClassType(path, fileName);
            myClassTypes.add(myClassType);
        }

        /*
         * Check if the entry is a directory recursively.
         */
        if (someCondition) {
            getMyClassTypes((path.equals("")) ? entry.getName() : path + "/" + entry.getName(), myClassTypes);
        }
    }
}