// 测试单例类 package code; class Typer{ private static Typer cache=null; private Typer(){} public static Typer createTyper(){ if(cache == null){ cache = new Typer(); } return cache; } } public class SingletonTest{ public static void main(String[] args) { Typer tp1 = Typer.createTyper(); Typer tp2 = Typer.createTyper(); System.out.println(tp1 == tp2); } }