打印具有 5 个最高值的键

Question

我有一个 HashMap 定义为：

Map<String, Double> data = new HashMap<String, Double>();

我正在尝试打印出具有最高 Double 值的 5 个字符串。我尝试通过对每个循环运行 5 次并保存最高值来做到这一点，同时我将整个 HashMap 迭代 5 次，但在 if 语句中出现空指针异常错误。

int highest = 0;

String highestkey;

 for(int i=0; i<5; i++){

     for(Map.Entry<String, Double> x : data.entrySet()){

        if(data.get(x) > highest){

           highestkey = x.getKey();

        }

     }

     System.out.println(highestkey);

     info_words.remove(highestkey);

  }

我的代码应该做的是在解析 HashMap 时跟踪最高的 Double 值，然后最终打印最高的键，然后将其删除，因此没有重复，然后再重复该过程 4 次，但它不能作为故意的

Answer 1

尝试这个：&nbsp; &nbsp; &nbsp; &nbsp; Double highest = 0.0;&nbsp; &nbsp; &nbsp; &nbsp; String highestkey = "";&nbsp; &nbsp; &nbsp; &nbsp; for (int i = 0; i < 5; i++) {&nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; for (Map.Entry<String, Double> x : data.entrySet()) {&nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; if (x.getValue() > highest) {&nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; highest = x.getValue();&nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; highestkey = x.getKey();&nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; }&nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; }&nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; System.out.println(highestkey);&nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; //remove highest here&nbsp; &nbsp; &nbsp; &nbsp; }