如何消除jsp表达式语言中的重复值? [英] how to eliminate duplicate values in jsp expression language?

问题描述

<c:forEach items="${listOfRoutes}" var = "route">
                <option value="${route.source }" >${route.source }</option>
              </c:forEach>

此处listOfRoutes包含Route(id，source，destination)对象. 在这里，我只想显示不同的来源. 如何做到这一点，请帮助我.

here the listOfRoutes contains Route(id,source,destination) objects. here i want to show only distinct sources. how to do this, plz help me.

推荐答案

您可以使用Set通过迭代列表存储源，因为Set不允许重复，然后在选项中使用Set来填充源，请在下面的代码中查看.

You can use Set to store source by iterating list because Set doesnot allow duplicate then use Set to populate source in the option, please have a look in below code.

<%
 Set setSource = new HashSet(); 
for(Route route:listOfRoutes){
 setSource.add(route.getSource()); 
 }
 %>


<c:forEach items="${setSource}" var = "source">
<option value="${source}" >${source}</option>
</c:forEach>

如果您希望选项具有排序值，请使用TreeSet.

if you want options to have sorted values, then please use TreeSet.

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