Error with my for loop

Version 1.7.10 

I created my loop for for file but I have an error that tells me that I am forced to use an Object my I do not understand I would like a little help if possible

I searched properties obviously on the internet but without finding impossible to find what it is not

```java
final Collection files = FileUtils.listFiles(this.modDirectory, null, true);
            for (final File file : files) {
                if (file.getName().toLowerCase().contains("liteloader".toLowerCase())) {
                    this.strangeFiles.add(file);
                }
                if (file.getName().toLowerCase().contains("ray".toLowerCase())) {
                    this.strangeFiles.add(file);
                }
                if (file.getName().toLowerCase().contains("vape".toLowerCase())) {
                    this.strangeFiles.add(file);
                }
                if (file.getName().toLowerCase().contains("radar".toLowerCase())) {
                    this.strangeFiles.add(file);
                }
                if (file.getName().toLowerCase().contains("xray".toLowerCase())) {
                    this.strangeFiles.add(file);
                }

            }
```

it's this code party that's not going