java - 类型 new Comparator(){} 必须实现继承的抽象方法 Comparator.compare(Object, Object)

Question

请帮助她。我有一个错误

  Collections.sort(var4, new Comparator() {
     public int compare(TreeMap var1, TreeMap var2) {
        return ((String)var1.get("col_3")).compareTo((String)var2.get("col_3"));
     }
  });

Answer 1

通过添加到 Comparator 来尝试这种方式，

Collections.sort(var4, new Comparator<TreeMap>() 
{
     public int compare(TreeMap var1, TreeMap var2) 
     {
        return ((String)var1.get("col_3")).compareTo((String)var2.get("col_3"));
     }
});