我试图从 HashMap 中随机生成“n”个项目,其中“n”由用户确定。
这是我到目前为止所拥有的:
public static void main(String []args){
int numColors = 3;
HashMap<String, String> map = new HashMap<String, String>();
map.put("White","FFFFFF");
map.put("Blank","000000");
map.put("Red","ED0A15");
map.put("Green","06F76C");
map.put("Blue","0689FF");
map.put("Sky Blue","00C2FC");
map.put("Light Blue","08F0FC");
map.put("Silver","C0BFC5");
map.put("Mint","ABD3CA");
map.put("Off White","FFEFF0");
map.put("Purple","736FFA");
map.put("Lavendar","DEBEEF");
map.put("Hot Pink","F5159A");
map.put("Pink","DB39CC");
map.put("Light Pink","F5C2E3");
map.put("Blush","C95FA7");
map.put("Orange","D4361B");
map.put("Yellow","DEF231");
map.put("Warm White","F3E4C3");
map.put("Turquoise","01DCA4");
List<String> valuesList = new ArrayList<String>(map.values());
int randomIndex = new Random().nextInt(valuesList.size());
String randomValue = valuesList.get(randomIndex);
System.out.printf(randomValue);
}
它为我打印了我想要的 1 个随机颜色(以十六进制表示),但是我不确定如何/使用哪个循环来从 map 生成 3 个随机十六进制颜色。我将 numColors 声明为 3 只是为了尝试测试一下。
这是我最终的结果:
public static void main(String []args){
int numColors = 3;
HashMap<String, String> map = new HashMap<String, String>();
map.put("White","FFFFFF");
map.put("Blank","000000");
map.put("Red","ED0A15");
map.put("Green","06F76C");
map.put("Blue","0689FF");
map.put("Sky Blue","00C2FC");
map.put("Light Blue","08F0FC");
map.put("Silver","C0BFC5");
map.put("Mint","ABD3CA");
map.put("Off White","FFEFF0");
map.put("Purple","736FFA");
map.put("Lavendar","DEBEEF");
map.put("Hot Pink","F5159A");
map.put("Pink","DB39CC");
map.put("Light Pink","F5C2E3");
map.put("Blush","C95FA7");
map.put("Orange","D4361B");
map.put("Yellow","DEF231");
map.put("Warm White","F3E4C3");
map.put("Turquoise","01DCA4");
List<String> keys = new ArrayList<String>(map.keySet());
Random rand = new Random();
for (int i = 0; i < numColors; i++) {
String key = keys.get(rand.nextInt(keys.size()));
System.out.println(map.get(key));
}
}
最佳答案
一个简单的解决方案是使用Collections.shuffle(map)
来打乱整个 map 。然后迭代它并选择前 n 个元素。
当然,如果 map 很大并且您只需要几个元素,那么这是没有意义的。
编辑:
当然,使用此解决方案,您不会得到任何重复的条目
关于java - 从 map 中随机选择 n 个项目,我们在Stack Overflow上找到一个类似的问题: https://stackoverflow.com/questions/25167823/