Exercism——ResistorColor

题目：

解法一：

package exercism;

import java.util.HashMap;
import java.util.Map;


public class ResistorColor {
	private Map<String,Integer> colorMap;
	private String[] colors = {"Black","Brown","Red","Orange","Yellow","Green","Blue","Violet","Grey","White"};
	private Integer[] points = {0,1,2,3,4,5,6,7,8,9};

	public ResistorColor() {
		colorMap = new HashMap<>();
		for (int i = 0; i < colors.length; i++) {
			colorMap.put(colors[i],points[i]);
		}
	}

	public int colorCode(String color) {
		return colorMap.get(color);
	}

	public String[] getColors() {
		return colors;
	}

}

解法二：

class ResistorColor {
    String[] colors() {
        return new String[]{"black", "brown", "red", "orange", "yellow", "green", "blue", "violet", "grey", "white"};

    int colorCode(String color) {
        return java.util.Arrays.asList(colors()).indexOf(color);
        		// 只有List才有indexOf方法
    	}
    }
}

解法三：

import static java.util.Arrays.stream;

class ResistorColor {

   private enum Colors {
      black, brown, red, orange, yellow, green, blue, violet, grey, white
   }

   int colorCode(String color) {
      return Colors.valueOf(color).ordinal();
   }

   String[] colors() {
      return stream(Colors.values())
         .map(Enum::name)
         .toArray(String[]::new);
   }
}

Conclusion:

• enum类.valueof().ordinal()方法可以获得field的下标
• “：：” 左边表示作用域（类或对象）、右边表示作用域的方法