如果constructor里调用了一个成员方法，这个方法被子类override了，当初始化一个子类实例时，父类的构造函数被的调用，此时父类构造函数的上下文里调用的成员方法，是父类的实现还是子类的实现？
你能不用运行代码，就能准确说出这些语句会打印什么出来呢？

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ABAP

class ZCL_SUPER definition public
  create public .
public section.
  methods CONSTRUCTOR .
  methods SET_I
    importing
      !IV_I type INT4 .
protected section.
private section.
  data MV_SUPER type INT4 .
ENDCLASS.
CLASS ZCL_SUPER IMPLEMENTATION.
  method CONSTRUCTOR.
    me->set_i( 100 ).
  endmethod.
  method SET_I.
    me->mv_super = iv_i.
  endmethod.
ENDCLASS. class ZCL_SUB definition public
  inheriting from ZCL_SUPER
  final
  create public .
public section.
  methods PRINT .
  methods SET_I
    redefinition .
protected section.
private section.
  data MV_SUB type I value 1 ##NO_TEXT. ENDCLASS.
CLASS ZCL_SUB IMPLEMENTATION.
  method PRINT. WRITE: / ' sub:' , mv_sub.
  endmethod.
  METHOD set_i. super->set_i( iv_i = iv_i ).
    me->mv_sub = iv_i. WRITE: / 'mv_sub assigned by: ' , iv_i.
  ENDMETHOD.
ENDCLASS. 

测试：

NEW zcl_sub( )->print( ). 

测试结果：sub: 1

Java

public class SuperClass{ private int mSuperX; public SuperClass(){
        setX(99);
    } public void setX(int x){
        mSuperX = x;
    }
} public class SubClass extends SuperClass{ private int mSubX = 1; public SubClass(){} @Override public void setX(int x){ super.setX(x);
        mSubX = x;
        System.out.println("SubX is assigned " + x);
    } public void printX(){
        System.out.println("SubX = " + mSubX);
    }
} 

test:

public static void main(String[] args){
        SubClass sc = new SubClass();
        sc.printX();
    } 

测试结果：

JavaScript

function SuperClass(){ this.setX(99);
}

SuperClass.prototype = { mSuperX : 0, setX : function(x){ this.mSuperX = x;
    }
}; function SubClass(){  
    SuperClass.call(this); this.mSubX = 1;
}  

SubClass.prototype = new SuperClass();  

SubClass.prototype.setX = function(x){
        SuperClass.prototype.setX(x); this.mSubX = x; console.log("SubX is assigned " + x);
};

SubClass.prototype.print = function(){ console.log("SubX: " + this.mSubX);
} 

test:

var sub = new SubClass();
sub.print(); 

测试结果:

详细分析在我的SAP community博客里: A reminder for using constructor in OO world
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网站标题：你真的会用ABAP,Java和JavaScript里的constructor么?
本文来源：http://scyanting.com/article/iejojs.html