问题描述

我正在尝试编译以下代码:

私有字符串 dataToString(){映射数据 = (HashMap) getData();字符串 toString = "";for( MyClass.Key key: data.keySet() ){toString += key.toString() + ":" + data.get(key);返回字符串；}
我在 for 行中收到一条错误消息:
<上一页>不兼容的类型找到:java.lang.Object必需:MyClass.Key

getData() 方法返回一个 Object(但在这种情况下，返回的 Object 具有 HashMap结构体).MyClass.Key 是我为我的应用程序创建的枚举(在另一个类文件 - MyClass 中).

当我在MyClass.java中创建一个相同结构的foreach循环时，我没有遇到这个问题.

我做错了什么?

一种更有效的方法:

 Mapdata = (HashMap) getData();StringBuffer sb = new StringBuffer();for (Map.Entry entry : data.entrySet()) {sb.append(entry.getKey());sb.append(":");sb.append(entry.getValue());}返回 sb.toString();

如果可能的话，定义getData"这样你就不需要演员表了.

I am trying to compile the following code:

private String dataToString(){
    Map data = (HashMap<MyClass.Key, String>) getData();
    String toString = "";
    for( MyClass.Key key: data.keySet() ){
        toString += key.toString() + ": " + data.get( key );
    return toString;
}

I get an error in the for line that says:

incompatible types
found : java.lang.Object
required: MyClass.Key

The getData() method returns an Object (but in this case the Object returned has the HashMap structure). MyClass.Key is an enum that I have created for the purposes of my application (in another class file - MyClass).

When I created a foreach loop with the same structure in MyClass.java, I did not encounter this problem.

What am I doing wrong?

A slightly more efficient way to do this:

  Map<MyClass.Key, String> data = (HashMap<MyClass.Key, String>) getData(); 
  StringBuffer sb = new StringBuffer();
  for (Map.Entry<MyClass.Key,String> entry : data.entrySet()) {
       sb.append(entry.getKey());
       sb.append(": ");
       sb.append(entry.getValue());
   }
   return sb.toString();

If at all possible, define "getData" so you don't need the cast.

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