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| 23. 14. 9. 多态性 |
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<HTML>
<HEAD>
<TITLE>Runtime Polymorphism</TITLE>
</HEAD>
<BODY>
<H1>Runtime Polymorphism</H1>
<%!
javax.servlet.jsp.JspWriter localOut;
class BaseClass
{
public void print() throws java.io.IOException
{
localOut.println("Hello from BaseClass...<BR>");
}
}
class DerivedClass1 extends BaseClass
{
public void print() throws java.io.IOException
{
localOut.println("Hello from DerivedClass1...<BR>");
}
}
class DerivedClass2 extends BaseClass
{
public void print() throws java.io.IOException
{
localOut.println("Hello from DerivedClass2...<BR>");
}
}
class DerivedClass3 extends BaseClass
{
public void print() throws java.io.IOException
{
localOut.println("Hello from DerivedClass3...<BR>");
}
}
%>
<%
localOut = out;
BaseClass a1 = new BaseClass();
DerivedClass1 b1 = new DerivedClass1();
DerivedClass2 c1 = new DerivedClass2();
DerivedClass3 d1 = new DerivedClass3();
BaseClass baseClassVariable;
baseClassVariable = a1;
baseClassVariable.print();
baseClassVariable = b1;
baseClassVariable.print();
baseClassVariable = c1;
baseClassVariable.print();
baseClassVariable = d1;
baseClassVariable.print();
%>
</BODY>
</HTML>
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