//People類
package?com.immoc;
public?class?People?{
public?void?say()?{
?System.out.println("人類具有說話的能力");
}
}
//Chinese類
package?com.immoc;
public?class?Chinese?extends?People?{
public?void?say()?{
?System.out.println("中國人說中國話");
}
}
//American類
package?com.immoc;
public?class?American?extends?People?{
public?void?say()?{
?System.out.println("美國人說英語");
}
}
//Test類
package?com.immoc;
public?class?Test?{
?public?static?void?main(String[]?args)?{
People?ch=new?Chinese();
People?am=new?American();
ch.say();
am.say();
?}
}
//APeople類
package?com.immoc;
public?abstract?class?APeople?{
public?abstract??void?say();
}

使用APeople類的時候把Chinese，American，Test類中的People改成APeople