在/ sdcard中创建目录失败

Question

我一直在尝试以/sdcard编程方式创建目录，但无法正常工作。以下代码始终输出directory not created.

boolean success = (new File("/sdcard/map")).mkdir(); 

if (!success) {

    Log.i("directory not created", "directory not created");

} else {

    Log.i("directory created", "directory created");

}