遍历目录修改文件后缀名

想要在手机上观看JavaApi，但是找了许久没要找到，只好自己把API转换成word文档查看

import java.io.File;
import java.io.FileInputStream;
import java.io.FileOutputStream;
import java.io.InputStream;
import java.io.OutputStream;

public class ChangeFile {
	public static String RootFile;
	public static String RootFilePath;
	public static String NewFilePath;
	public static String RootFileName;
	
	public static void main(String[] args) {
		String FileName = "E:\\APIword"+File.separator;
		File file = new File(FileName);
		long start = System.currentTimeMillis();
		ListFile(file);
		long end = System.currentTimeMillis();
		System.out.print(end-start);
	}

	private static void ListFile(File file) {
		if(file != null){
			//判断是否是文件
			if(file.isFile()){
				ChangeFile(file);
			}
			//遍历所有文件
			if(file.isDirectory()){			
				File[] File = file.listFiles();
				if(File!=null){
					for(int i=0; i