如果你想确保它被创建，那么:

final String path = "target/logs/";
final File logsDir = new File(path);
final boolean logsDirCreated = logsDir.mkdir();
if (!logsDirCreated) {
    final boolean logsDirExists = logsDir.exists();
    assertThat(logsDirExists).isTrue();
}

因为mkDir()返回一个布尔值，如果你不使用这个变量，findbugs会为它哭泣。这也不好…

mkDir()只在mkDir()创建时返回true。 如果dir存在，它将返回false，因此要验证您创建的dir，如果mkDir()返回false，则只调用exists()。

assertThat()将检查结果，如果exists()返回false则失败。Ofc您可以使用其他东西来处理未创建的目录。

在Java 7中，您可以使用Files.createDirectories()。

例如:

Files.createDirectories(Paths.get("/path/to/directory"));

您可以尝试FileUtils#forceMkdir

FileUtils.forceMkdir("/path/directory");

这个库有很多有用的函数。

虽然这个问题已经有了答案。我想多放点东西，比如。 如果存在与您试图创建的目录名称相同的文件，则会提示错误。为将来的访客准备的。

public static void makeDir()
{
    File directory = new File(" dirname ");
    if (directory.exists() && directory.isFile())
    {
        System.out.println("The dir with name could not be" +
        " created as it is a normal file");
    }
    else
    {
        try
        {
            if (!directory.exists())
            {
                directory.mkdir();
            }
            String username = System.getProperty("user.name");
            String filename = " path/" + username + ".txt"; //extension if you need one

        }
        catch (IOException e)
        {
            System.out.println("prompt for error");
        }
    }
}

对于java 7及以上版本:

Path path = Paths.get("/your/path/string");
Files.createDirectories(path);

在创建之前检查目录或文件是否存在似乎是不必要的，from createDirectories javadocs:

Creates a directory by creating all nonexistent parent directories first. Unlike the createDirectory method, an exception is not thrown if the directory could not be created because it already exists. The attrs parameter is optional file-attributes to set atomically when creating the nonexistent directories. Each file attribute is identified by its name. If more than one attribute of the same name is included in the array then all but the last occurrence is ignored. If this method fails, then it may do so after creating some, but not all, of the parent directories.

这种方式为我做一个单一的目录或更多或他们: 需要导入java.io.File; /*输入下面的代码添加目录dir1或检查是否存在dir1，如果不存在，则创建dir2和dir3 */

    File filed = new File("C:\\dir1");
    if(!filed.exists()){  if(filed.mkdir()){ System.out.println("directory is created"); }} else{ System.out.println("directory exist");  }

    File filel = new File("C:\\dir1\\dir2");
    if(!filel.exists()){  if(filel.mkdir()){ System.out.println("directory is created");   }} else{ System.out.println("directory exist");  }

    File filet = new File("C:\\dir1\\dir2\\dir3");
    if(!filet.exists()){  if(filet.mkdir()){ System.out.println("directory is  created"); }}  else{ System.out.println("directory exist");  }