test.java

来自「Practical Java也是一本和J2ME手机游戏开发相关的书」· Java 代码 · 共 10 行

public void foo(MutablePinNumbers p)
{}
public void bar(ImmutablePinNumbers p)
{}
MutablePinNumbers m = new MutablePinNumbers("person1", 101,
                                            201);
ImmutablePinNumbers im = new ImmutablePinNumbers("person2", 102,
                                                  202);
foo((MutablePinNumbers)im);   //Compiler error
bar((ImmutablePinNumbers)m);  //Compiler error