小编wol*_*lfd的帖子

有谁知道为什么会出错？我一直在尝试这么长时间,我似乎无法弄明白.它错误地"无法读取未定义的属性0",但它已明确定义.(或者我认为)

var categorySix = [["test"]["test2"],["testing"]["one"],["two"]["three"]];
document.write(categorySix[0][0]);

所以我在我的代码中有这个循环,需要两个单独工作的迭代器.但是,当它尝试使用rbIterator.next()时,java会抛出ConcurrentModificationException.我如何阻止这种情况发生？谢谢

Iterator<Road> raIterator = roads.listIterator(0); //I also tried .iterator(), with no avail
while(raIterator.hasNext()){
    Road ra = raIterator.next();
    Iterator<Road> rbIterator = roads.listIterator(0);
    while(rbIterator.hasNext()){
        Road rb = rbIterator.next();
        //snipped code that adds a road to the list
        roads.add(xyz);
    }
}