<%
//Retrieving the Server list from dispatcher
Collection<Server> svr = (Collection<Server>)request.getAttribute("stuff");
ArrayList<String> serverIds = new ArrayList<String>();
for(Server i : svr )
serverIds.add(i.getId());
String [] svrIds = new String[svr.size()];
serverIds.toArray(svrIds);
%>
<!DOCTYPE html PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN" "http://www.w3.org/TR/html4/loose.dtd">
<html>
<head>
<script type="text/javascript">
var instanceIds = new Array(<%=svrIds%>);
//test somethings in there
alert(instanceIds[0]);
</script>
</head>
</html>
-
possible duplicate of Converting a Java ArrayList of strings to a JavaScript arrayJason C– Jason C2014-03-22 15:39:17 +00:00Commented Mar 22, 2014 at 15:39
Add a comment
|
4 Answers
If you want to use Java code to write the code for a Javascript data structure, probably the simplest way to do it is to use a JSON library for Java. A JSON string can be interpreted as Javascript code.
If you want to use JSON.simple, then there are examples here of how to generate the JSON string:
http://code.google.com/p/json-simple/wiki/EncodingExamples
In your code, you should be able to do something like this:
var instanceIds = <%= JSONValue.toJSONString(serverIds) %>
You shouldn't need to convert your ArrayList to a Java array. Note that this function is sensitive to what type you pass into it; an array actually won't work in this instance.
Also, to do this you will need to install the JSON.simple JAR file and import org.json.simple.JSONValue in your JSP.
2 Comments
stackoverflow
could you produce a simple example against my code above? Thanks greatly
Nate C-K
Added. I wasn't able to test this in a JSP setup like you apparently have, but I did test the function on an
ArrayList<String> and it generated a JSON array as expected.<%
String[] jArray= new String[2];
jArray[0]="a";
jArray[1]="b";
StringBuilder sb = new StringBuilder();
for(int i=0;i<jArray.length;i++)
sb.append(jArray[i]+",");
%>
<script type="text/javascript">
temp="<%=sb.toString()%>";
var strr = new Array();
strr = temp.split(',','<%=jArray.length%>');
alert("array: "+strr);
</script>
Comments
Both Thomas and Nates answers are good. However, an alternative is to write each into an hidden field then have your js look them up in the DOM.
Comments
I'd say you have to use a JavaScript compatible string representation of svrIds, like String srvIdsString = "\"element1\",\"element2\"";. To get that, iterate over the array and append "\"" + svrIds[i] + "\"," to your string representation.
Note that the last comma should either be removed again or not added at all (e.g. by skipping it for the last element or adding it to the front and skipping it for the first element).
Example:
StringBuilder idArrayBuilder = new StringBuilder();
for( String id : srvIds ) {
if( idArrayBuilder.length() > 0 ) {
idArrayBuilder.append(",");
}
idArrayBuilder.append( "\"" ).append(id).append( "\"" );
}
String result = idArrayBuilder.toString();
The rest is up to you :)
