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cannot understand the exception in my code,please help

 
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the null Point exception occurs at the at but I think my constructor has initialized the point2D objects.
please point out my mistake. tons of thanks.

 
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liu hao wrote:the null Point exception occurs at the at



in which line you invoking this ? instead please tell the line number
 
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You are never initialising the Point2D objects in your MyRectangle class. In your constructor (or in the declaration) you need to create new objects for these. For example, your method setBottomLeftPoint attempts to do something like null.setLocation(...).

OR, simply assign the Point2D objects that you are passing to your constructor to your instance variables.
 
liu hao
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a lot of thanks.It seems I didn't understand that staff thoroughly.
 
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