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