动态铸造。 ClassCastException

Question

everybody =) I'm trying to cast a string to Double this way

Class.forName("java.lang.Double").cast("100")

But it throws ClassCastException. :(
What's wrong with this? And how can I achieve what I want.

Answer 1

You cannot cast a String do Double . If you want to get the Double representation for a String , you can either:

Double d = new Double("100");

or

double d = Double.parseDouble("100");

Answer 2

You're essentially trying to cast a String to Double like so

String s = "100";
Double d = (Double)s;

You can't do that. This is the reason for your ClassCastException.

You need to use Double.valueOf()