下面是代码我如何检查空指针异常
private static HashMap naturalNumbers = new HashMap();
static
{
naturalNumbers.put("zero", new Integer(0));
naturalNumbers.put("one", new Integer(1));
naturalNumbers.put("two", new Integer(2));
naturalNumbers.put("three", new Integer(3));
}
private static int findANumber(String partOfaNumber) throws Exception
{
int multiplicand = 0;
multiplicand += (Integer)naturalNumbers.get(partOfaNumber);
如果“获取”返回null,我该如何检查呢?
我曾尝试:
if ((Integer)naturalNumbers == null)
{
throw new Exception("Number not found");
}
return multiplicand;
}
但IDE甚至不接受它:无法从HashMap中转换为整数。
naturalNumbers的类型是HashMap中同时搜索,你为什么要(整数)naturalNumbers? – snow8261 2012-08-16 05:53:08