动态h:inputtext以支持jsf中的Bean数组[ClassCastException] [英] Dynamic h:inputtext to backing Bean Array in jsf [ClassCastException]

问题描述

我正在使用JSF 2.0 我在将inputTexts的值设置为double表时遇到问题.

I'm using JSF 2.0 I have a problem to set Values of inputTexts to a table of double.

我可以这样做:

<h:inputText value="#{myBean.table[0]}" /> 

但是，我想像这样循环进行:

But, I would like to do it in a loop like that:

<c:forEach var="i" begin="0" end="#{myBean.inputsNumber}">              
    <h:inputText  value="#{myBean.table[i]}" />     <br/>            
</c:forEach>   
<h:commandButton action="#{myBean.calculate}" value="Calculate" /> 
Result: #{myBean.result}

这是我的后援豆:

@ManagedBean
@SessionScoped
public class MyBean {

    private double[] table;
    private double result;

    public MyBean() {
        table = new double[100];
    }

    public void calculate() {
        for (int i = 0; i < table.length; i++) {
            result += table[i];
        }
    }

    public double[] getTable() {
        return table;
    }

    public int getInputsNumber() {
        return table.length;
    }

    public double getResult() {
        return result;
    }

}

我试图将所有组件绑定到HtmlInputText数组，但是我无法解决. 我遇到了这个异常:ClassCastException

I tried to bind all components to an array of HtmlInputText, but I could not solve it. i got this exception : ClassCastException

推荐答案

有2个问题:

1. <c:forEach end>包含在内.您需要从中扣除1，否则在提交时会以ArrayIndexOutOfBoundsException结尾.

1. The <c:forEach end> is inclusive. You need to take 1 off from it, otherwise you end up with ArrayIndexOutOfBoundsException when submitting.

<c:forEach var="i" begin="0" end="#{myBean.inputsNumber - 1}">

但是，更好的方法是迭代数组本身并通过varStatus获取索引.

A better approach is however to just iterate over the array itself and get the index by varStatus.

<c:forEach items="#{myBean.table}" varStatus="loop">
    <h:inputText value="#{myBean.table[loop.index]}" />
</c:forEach>

---

EL中的双精度字符被视为Double，而不是double.因此，您需要Double[]而不是double[]，否则在提交时最终会得到ClassCastException.

---

A double in EL is treated as Double, not as double. So you need Double[] instead of double[], otherwise you end up with ClassCastException when submitting.

private Double[] table;

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