Getting NullPointerException while uploading file(s) using p:fileUpload

Question

I'm having issues with <p:fileUpload> constantly receiving java.lang.NullPointerException.

Here's my code:

XHTML:

<h:form enctype="multipart/form-data">
    <p:growl id="messages" showDetail="true" />
    <p:fileUpload value="#{fileUploadView.file}" mode="simple"/>
    <p:commandButton value="Submit" ajax="false" actionListener="#{fileUploadView.upload}"/>
</h:form>

fileUploadView.java

public class FileUploadView {

    public String[] inFileString;
    private UploadedFile file;

    public UploadedFile getFile() {
        return file;
    }

    public void setFile(UploadedFile file) {
        this.file = file;
    }

    public void upload() throws IOException {
        if (file != null) {
            InputStream strumyk = file.getInputstream();
            InputStreamReader is = new InputStreamReader(strumyk);
            BufferedReader reader = new BufferedReader(is);
            inFileString[0] = reader.readLine();
            FacesMessage readStream = new FacesMessage(inFileString[0]);

            FacesMessage message = new FacesMessage("Succesful", file.getFileName() + " is uploaded.");
            FacesContext.getCurrentInstance().addMessage(null, message);
        }
    }
}

Am I doing something wrong here?