我试图下载一个位图文件到我的电脑，但在JPEG格式。这里是我的代码片段。

private void SaveImage(Bitmap finalBitmap) {

    String root = Environment.getExternalStorageDirectory().toString();
    File myDir = new File(root + "/Users/johnathan/Downloads");
    if (!myDir.exists()) {
        myDir.mkdirs();
    }
    Random generator = new Random();
    int n = 10000;
    n = generator.nextInt(n);
    String fname = "Image-"+ n +".jpeg";
    File file = new File (myDir, fname);
    if (file.exists ())
        file.delete ();
    try {
        FileOutputStream out = new FileOutputStream(file);
        finalBitmap.compress(Bitmap.CompressFormat.JPEG, 90, out);
        out.flush();
        out.close();

    } catch (Exception e) {
        System.out.println("Didn't work");
        e.printStackTrace();
    }
}

我不断收到错误No such file or directory（ENOENT）：

W/System.err: java.io.FileNotFoundException: /storage/emulated/0/Users/johnathan/Downloads/Image-4209.jpeg: open failed: ENOENT (No such file or directory)
W/System.err:     at libcore.io.IoBridge.open(IoBridge.java:575)
W/System.err:     at java.io.FileOutputStream.<init>(FileOutputStream.java:236)
W/System.err:     at java.io.FileOutputStream.<init>(FileOutputStream.java:186)
W/System.err:     at com.example.testforcamera.MainActivity.SaveImage(MainActivity.java:173)
W/System.err:     at com.example.testforcamera.MainActivity.onActivityResult(MainActivity.java:115)
W/System.err:     at android.app.Activity.dispatchActivityResult(Activity.java:8659)
W/System.err:     at android.app.ActivityThread.deliverResults(ActivityThread.java:5857)
W/System.err:     at android.app.ActivityThread.handleSendResult(ActivityThread.java:5903)
W/System.err:     at android.app.servertransaction.ActivityResultItem.execute(ActivityResultItem.java:54)
W/System.err:     at android.app.servertransaction.ActivityTransactionItem.execute(ActivityTransactionItem.java:45)
W/System.err:     at android.app.servertransaction.TransactionExecutor.executeCallbacks(TransactionExecutor.java:135)
W/System.err:     at android.app.servertransaction.TransactionExecutor.execute(TransactionExecutor.java:95)
W/System.err:     at android.app.ActivityThread$H.handleMessage(ActivityThread.java:2438)
W/System.err:     at android.os.Handler.dispatchMessage(Handler.java:106)
W/System.err:     at android.os.Looper.loopOnce(Looper.java:226)
W/System.err:     at android.os.Looper.loop(Looper.java:313)
W/System.err:     at android.app.ActivityThread.main(ActivityThread.java:8663)
W/System.err:     at java.lang.reflect.Method.invoke(Native Method)
W/System.err:     at com.android.internal.os.RuntimeInit$MethodAndArgsCaller.run(RuntimeInit.java:567)
W/System.err:     at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:1135)
W/System.err: Caused by: android.system.ErrnoException: open failed: ENOENT (No such file or directory)
W/System.err:     at libcore.io.Linux.open(Native Method)
W/System.err:     at libcore.io.ForwardingOs.open(ForwardingOs.java:567)
W/System.err:     at libcore.io.BlockGuardOs.open(BlockGuardOs.java:273)
W/System.err:     at libcore.io.ForwardingOs.open(ForwardingOs.java:567)
W/System.err:     at android.app.ActivityThread$AndroidOs.open(ActivityThread.java:8523)
W/System.err:     at libcore.io.IoBridge.open(IoBridge.java:561)
W/System.err:   ... 19 more

我一直在互联网上寻找解决方案，但没有任何效果。虽然大多数答案都很过时。这里有没有人可能有一个解决方案？我已经在这一部分工作了几个小时了。
谢谢