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My idea was to use casting to get a StringBuilder object to pass a valid argument to a method. Like this:

public TTTButton(String color) {
    StringBuilder sb = new StringBuilder();
    sb.append("Color."+ color.toString().toUpperCase());
    this.setBackground((Color)(Object)sb);// Runtime Exception: java.lang.StringBuilder cannot be cast to java.awt.Color

Please share your thoughts on why such things are impossible (or maybe they are possible)?

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    Because a cast is not the same thing as an Eval function. Commented Jan 14, 2014 at 0:17
  • You can't cast it, because a String is not a Color. You can perform a lookup, as in my answer to your previous question. Commented Jan 14, 2014 at 0:19
  • A StringBuilder is not a Color. Casting only works if they actually are the right type. Commented Jan 14, 2014 at 0:19
  • Fyi, sb.append("a" + b) does sb.append(new StringBuilder("a").append(b).toString()) under the hood so your explicit StringBuilder is redundant. Commented Jan 14, 2014 at 0:19
  • @RobertHarvey, and if string arguments were automatically evaled as in the example, then System.out.println("new java.lang.String(\"foo\")"); would be ambiguous. Commented Jan 14, 2014 at 0:22

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String or StringBuilder is not Color type so you can't use casting here. Maybe try to use Color.getColor(colorName) where colorName is String.

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3 Comments

Note - where it is a String, not a StringBuilder...
As people explained before, you just cannot cast from String to Color because the interpreter won't know how to do such a conversion. For the sake of curiosity, a way to do what you want is like this import java.awt.Color; import bsh.EvalError; import bsh.Interpreter; public class ColorEval { public static void main(String[] args) throws EvalError { Interpreter bsh = new Interpreter(); bsh.eval("java.awt.Color c = java.awt.Color.BLACK"); Color black = (Color)bsh.eval("c"); System.out.println(black.equals(Color.BLACK)); } }
public TTTButton(String color) throws EvalError {Color passedColor = (Color)bsh.eval("Color."+ color.toString().toUpperCase()); this.setBackground(passedColor); Works fantastically! I think it allows to construct any method, argument or anything from string. Thanks!

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