// codes start2
class base{//a base class
3
4
// constructor5
public base(){
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System.out.println("base class construct");7
}8
// perform9
public void perform(){10
System.out.println("base class perform");11
}12
// destructor13
public void finalize(){14
System.out.println("base class destruct");15
}16
}17
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class subbase extends base{// derive from base20
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// constructor22
public subbase(){23
System.out.println("sub class construct");24
}25
// perform26
public void perform(){27
System.out.println("sub class perform");28
}29
// destructor30
public void finalize(){31
System.out.println("sub class destruct");32
}33
}34
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public class casting{// test casting class36
// constructor37
public casting(){38
System.out.println("begin casting test");39
}40
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public static void main(String args[]){42
base father = new base();43
subbase son = new subbase();44
45
father.perform();46
son.perform();47
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father = (base)son; // <1>49
father.perform();50
51
son = (subbase)father; // <2>52
son.perform();53
54
father = (base)((subbase)father); // <3>55
father.perform();56
}57
}58
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// codes end60
Today ,when i go for a interview ,the project manager asked me this question !Acturally ,It's just relate to the knowledge of reference && object !
Be carefull ,Nothing !
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