forEach iteration tag: This tag is used to iterate over a series of objects in a Collection set and can specify the number of iterations.
The general format used is as follows:
<c:forEach items="collection" var="varName"
[varstatus="varStatusName"][begin="begin"] [end="end"] [step="step"]>
body content
</c:forEach>
The attributes used in this tag are described below:
var: The name of the object stored in the Collection collection class.
items: The name of the collection class to iterate over.
varStatus: Stores the state information of an iteration and has access to the information of the iteration itself.
Begin: If a begin value is specified, the iteration starts from items[begin], and if no begin value is specified, the iteration starts from the first value of the set.
End: Indicates the end of the iteration to the end bit of the set, or the last bit of the set in the iteration until the end value is specified.
Step: Specifies the step of the iteration.
Here are two examples of using forEach
<%@ page contentType="text/html;charset=GB2312"%>
<%@ taglib prefix="c" uri="http://java.sun.com/jsp/jstl/core"%>
<html>
<head>
<title>c:forEach Use examples</title>
</head>
<body>
<%
//------------------ Sets the initial value of an array-------------
String name[] = new String[4];
name[0] = "Guo Jingjing";
name[1] = "Zhang Yining";
name[2] = "He Wenna";
name[3] = "Marine";
request.setAttribute("name", name);
%>
<!---------use forEach Output Array Element Value and Related Attributes in Iteration-->
<c:forEach items="${name}" var="currentName"
varStatus="currentVarStaus">
The name of the current champion:<c:out value="${currentName}" />;
The current champion index number is:<c:out value="${currentVarStaus.index}" />;<br>
Current Total Iteration<c:out value="${currentVarStaus.count}" />second;
<c:if test="${currentVarStaus.first}">Currently is the first iteration operation</c:if>
<c:if test="${currentVarStaus.last}">Currently the last iteration operation</c:if>
<hr>
</c:forEach>
</body>
</html>The result of running the display is:
The name of the current champion is: Guo Jingjing; the index number of the current champion is: 0; Currently iterates once in total; currently is the first iteration operation -------------------------------------------------------------------------------- The name of the current champion is Zhang Yining; the index number of the current champion is: 1; The current total number of iterations is 2; -------------------------------------------------------------------------------- The name of the current champion is: He Wenna; the index number of the current champion is: 2; The current total number of iterations is 3; -------------------------------------------------------------------------------- The name of the current champion is Marine; the current champion index number is 3; Currently a total of 4 iterations; currently the last iteration operation --------------------------------------------------------------------------------
A second example will provide an in-depth introduction to the use of bengin and end
<%@ page contentType="text/html;charset=GBK" %>
<%@ page isELIgnored="false" %>
<%@ taglib prefix="c" uri="http://java.sun.com/jsp/jstl/core" %>
<html>
<head>
<title>JSTL: -- forEach Label Instance</title>
</head>
<body>
<h4><c:out value="forEach Example"/></h4>
<hr>
<%
String items[] = new String[5];
items[0] = "Core Label Library";
items[1] = "International Label Library";
items[2] = "SQL Label Library";
items[3] = "XML Label Library";
items[4] = "Function Label Library";
request.setAttribute("items",items);
%>
<B><c:out value="Not specified begin and end Iteration of:" /></B><br>
<c:forEach var="item" items="${items}">
<c:out value="${item}"/><br>
</c:forEach>
<B><c:out value="Appoint begin and end Iteration of:" /></B><br>
<c:forEach var="item" items="${items}" begin="1" end="3" step="1">
<c:out value="${item}" /><br>
</c:forEach>
<B><c:out value="Output information for the entire iteration:" /></B><br>
<c:forEach var="item" items="${items}" begin="3" end="4" step="1" varStatus="s">
<c:out value="${item}" />Four attributes:<br>
Location, i.e. index:<c:out value="${s.index}" /><br>
Total number of iterations:<c:out value="${s.count}" /><br>
Is it the first position:<c:out value="${s.first}" /><br>
Is it the last position:<c:out value="${s.last}" /><br>
</c:forEach>
</body>
</html>
The result of running the test is:
forEach instance -------------------------------------------------------------------------------- Iterations for begin and end are not specified: Core Label Library International Label Library SQL Label Library XML Label Library Function Label Library Specify iterations for begin and end: International Label Library SQL Label Library XML Label Library Output information for the entire iteration: Four properties of the XML tag library: Location, i.e. index: 3 Total number of iterations: 1 Is this the first location:true Is it the last location: false Four properties of the function label library: Location, i.e. index:4 Total number of iterations: 2 Is it the first position: false Is it the last location:true
