Here you can find the source of writeStringKey(final Object key, final ObjectOutputStream oos)
private static void writeStringKey(final Object key, final ObjectOutputStream oos) throws IOException
//package com.java2s; import java.io.IOException; import java.io.ObjectOutputStream; public class Main { private static void writeStringKey(final Object key, final ObjectOutputStream oos) throws IOException { oos.writeObject(key);// w ww . jav a2 s . c om } }