如何通过其构造函数中的String参数更改JPanel的背景颜色？

Question

I have a program where I want to set the color of a JPanel when its object is created through its constructor. Right now this is what I have.

However this is obviously quite inefficient. I was wondering if there was some way I could pass the string parameter directly into the setBackground() method to set the color?

MyPanel(String bcolor) {
        super();
        if (bcolor.equals("red"))
            setBackground(Color.RED);
        if (bcolor.equals("blue"))
            setBackground(Color.BLUE);
        if (bcolor.equals("green"))
            setBackground(Color.GREEN);
        if (bcolor.equals("white"))
            setBackground(Color.WHITE);
        if (bcolor.equals("black"))
            setBackground(Color.BLACK);

    } 

Answer 1

I was wondering if there was some way I could pass the string parameter directly into the setBackground() method to set the color?

No, obviously, as there is no setBackground(String) method.

Now, there are a number of possible solutions you might employee, your current series of if statements is one solution, another might be to use some king of static Map which acts as a look up between the String value and the Color you want to use, for example...

public class MyPanel extends JPanel {

    protected static final Map<String, Color> COLOR_MAP = new HashMap<>();

    public MyPanel(String color) {
        setBackground(COLOR_MAP.get(color.toLowerCase()));
    }

    static {
        COLOR_MAP.put("red", Color.RED);
        COLOR_MAP.put("blue", Color.BLUE);
        COLOR_MAP.put("green", Color.GREEN);
        COLOR_MAP.put("white", Color.WHITE);
        COLOR_MAP.put("black", Color.BLACK);
    }

}

Answer 2

The simplest way would be to pass it the RGB values for the color you want in the constructor.

MyPanel(int r, int g, int b){
    super();
    setBackground(new Color(r,g,b));
}

If you really, really, want to use Strings, you could do this

String colorName; //note that this has to be exact spelling and capitalization of the fields in the Color class.
Field field = Class.forName("java.awt.Color").getField(colorName);
setBackground((Color) field.get(null));