Here you can find the source of isSystemIdentifier(URI localIdentifier)
public static boolean isSystemIdentifier(URI localIdentifier)
//package com.java2s; //License from project: Open Source License import java.net.URI; public class Main { public static URI LOCAL_SYSTEM_IDENTIFIER; public static boolean isSystemIdentifier(URI localIdentifier) { return localIdentifier.normalize().toString().equals(LOCAL_SYSTEM_IDENTIFIER.normalize().toString()); }/* w w w. ja v a 2 s .c o m*/ }