Question

我正在尝试在Drools中定义一个非常简单的函数，如下所示：

import java.util.List;

function int sumLengths(List<String> strings) {
    int counter = 0;
    for (String s : strings)
        counter += s.length();
    return counter;
}

但它给了我错误：

Exception in thread "main" java.lang.RuntimeException: [ function sumLengths (line:5):
Unable to resolve type List<String> while building function. java.lang.ClassNotFoundException: Unable to find class 'List<String>' ]

任何想法？

Answer 1

也许这是泛型问题（This指出了我的结论）。您是否尝试过以下（或类似）：

function int sumLengths(List strings) {
    int counter = 0;
    for (Object s : strings)
        counter += ((String) s).length();
    return counter;
}

如果它不起作用，你可以改用它：

function int sumLengths(String[] strings) {
    int counter = 0;
    int length = (strings != null) ? strings.length : -1;
    for (int idx = 0; idx < length; ++idx) {
        counter += strings[idx].length();
    }
    return counter;
}

Answer 2

更改为

function Boolean consulta(celda cref, java.util.List celdas) {

......

 celda c = (celda) celdas.get(y);
}

在Drools中“无法找到类”错误

2 个答案: