Java Hashmap returning a value from a given key, using random

I have a bit of a problem in regards to getting my program to work. I have created a hashmap that has a setting and the hashmap can hold 4 key/value pairs.

Now each key (0,1,2,3) is attached to a String 'value' that represents a colour ("white", "red"... etc).

Now I am using random to give me a random number from 0 to 3 to which I assign to an int variable.

I then use this variable to see if the collection contains this int key (which it will) and 开发者_运维问答then I wanted to assign that value assosiated with that key to a String variable to which I will then use in a method to change the color of a GUI panel (generating a random color when the event is triggered).

// changing yellow with the String variable representing the value 
// from the hashmap found by matching the key with the random int.
centerPanel.setBackground(Color.yellow);  

Can anyone help me out please? It's nearly 12am here and can probably figure it out in the morning but am having mind blanks!!

---

It seems to me this is begging for an array Color[4] indexed from 0 to 3 - rather than changing your random int to a String or Integer key and doing a Hash lookup.

---

Totally fake class that shows how to use an array with your random

public class foo
{
    private Color[] colors = { Color.red, Color.green, Color.blue, Color.yellow };

    public Color getColor()
    {
        return colors[getRandom(0, 3)];
    }

    private int getRandom(int min, int max)
    {
        return 2;
    }

    enum Color {
        red, green, blue, yellow;
    }
}

---

Use an array instead:

String[] colors = new String[]{"white", "red"... etc};
int random = random.nextInt(colors.length);

String randomColor = colors[random];

Edit:Substitute String for your Color class (or primitive) if you want to.

---

You need a method that converts the String into a actual color. I would use something like this:

public static Color stringToColor(final String value) {
    if (value == null) {
      return Color.black;
    }
    try {
      // get color by hex or octal value
      return Color.decode(value);
    } catch (NumberFormatException nfe) {
      // if we can't decode lets try to get it by name
      try {
        // try to get a color by name using reflection
        final Field f = Color.class.getField(value);

        return (Color) f.get(null);
      } catch (Exception ce) {
        // if we can't get any color return black
        return Color.black;
      }
    }
  }

(from 2D-Graphics/Convertsagivenstringintoacolor.htm">http://www.java2s.com/Tutorial/Java/0261_2D-Graphics/Convertsagivenstringintoacolor.htm)

---

For anyone interested in how I solved this (thanks to the help of other on here and tutorials on google):

    // fields
    private Color1[] colors = { Color1.red, Color1.green, Color1.blue, Color1.yellow };
    private int a2;
    private String getRandomColor;

    //constructor calling methods to generate a random value to 'a2' (0 to 3) and then setting variable a2 to the color as a string

    public SamTester()
    {
        setA2();
    }

    public void setA2()
    {
        a2 = (int)(Math.random()*4);
        getRandomColor = getColor().toString();
    }

    public Color1 getColor()
    {
       return colors[a2];
    }
________________________________________________________________________

        //inner class  
      class LeftClicked implements ActionListener
      {
          public void actionPerformed(ActionEvent e)
           {
               if(getRandomColor == "red")
               {
                   centerPanel.setBackground(Color.red);
               }
               else if (getRandomColor == "blue")
               {
                   centerPanel.setBackground(Color.blue);
               }
               else if (getRandomColor == "green")
               {
                   centerPanel.setBackground(Color.green);
               }
               else
               {
                   centerPanel.setBackground(Color.yellow);
               }
               setA2();
         }
        }

________________________________________________________________________

//basic enums class to represent the constant colors.

    public enum Color1
   {
    red, green, blue, yellow;
   }

Cheers all!