Explanation of ClassCastException in Java

Straight from the API Specifications for the ClassCastException: Thrown to indicate that the code has attempted to cast an object to a subclass of which it is not an instance. So, for example, when one tries to cast an Integer to a String, String is not an subclass of Integer, so a ClassCastException will be thrown.

Error in plot.window(…) : need finite ‘xlim’ values

The problem is that you’re (probably) trying to plot a vector that consists exclusively of missing (NA) values. Here’s an example: In your example this means that in your line plot(costs,pseudor2,type=”l”), costs is completely NA. You have to figure out why this is, but that’s the explanation of your error. From comments: Scott C Wilson: Another possible cause of …

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How can I solve the error LNK2019: unresolved external symbol – function?

One option would be to include function.cpp in your UnitTest1 project, but that may not be the most ideal solution structure. The short answer to your problem is that when building your UnitTest1 project, the compiler and linker have no idea that function.cpp exists, and also have nothing to link that contains a definition of multiple. A way to fix this is making use …

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com.mysql.jdbc.exceptions.jdbc4.CommunicationsException: Communications link failure

So, you have a com.mysql.jdbc.exceptions.jdbc4.CommunicationsException: Communications link failurejava.net.ConnectException: Connection refused I’m quoting from this answer which also contains a step-by-step MySQL+JDBC tutorial: If you get a SQLException: Connection refused or Connection timed out or a MySQL specific CommunicationsException: Communications link failure, then it means that the DB isn’t reachable at all. This can have one or more of the following causes: IP …

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How can I define an array of objects?

You are better off using a native array instead of an object literal with number-like properties, so that numbering (as well as numerous other array functions) are taken care of off-the-shelf. What you are looking for here is an inline interface definition for your array that defines every element in that array, whether initially present or introduced later: If …

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How to pip or easy_install tkinter on Windows

Well I can see two solutions here: 1) Follow the Docs-Tkinter install for Python (for Windows): Tkinter (and, since Python 3.1, ttk) are included with all standard Python distributions. It is important that you use a version of Python supporting Tk 8.5 or greater, and ttk. We recommend installing the “ActivePython” distribution from ActiveState, which includes everything …

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