[英]Passing a class as a parameter in a method and using this parameter in an If statement
I would like to have something like this: 我想要这样的东西:
public static List<Type> getProtocolls(Class clazz, Transaction trx) {
Iterator<Type> iterator = trx.getContext().getProtocolls()
List<Type> list = null;
while (iterator.hasNext()) {
if (iterator.next() instanceof clazz) {
list.add(iterator.next())
}
}
return list;
}
I am talking mainly about this part: (iterator.next() instanceof clazz)
- is this even possible to pass Class as a parameter like this? 我主要在谈论这部分:
(iterator.next() instanceof clazz)
-甚至有可能像这样将Class传递为参数吗? Eclipse says "clazz cannot be resolved to a type". Eclipse说“ clazz无法解析为一种类型”。
You could use the isAssignableFrom
method. 您可以使用
isAssignableFrom
方法。 Also, note you have two calls to next()
in the loop, so you'll be skipping half the elements - you should extract the result of this call to a local variable: 另外,请注意,您在循环中对
next()
进行了两次调用,因此您将跳过一半的元素-您应将此调用的结果提取到局部变量中:
while (iterator.hasNext()) {
Type t = iterator.next();
if (clazz.isAssignableFrom(t.getClass())) {
list.add(t)
}
}
EDIT: 编辑:
As @Fildor noted in the comments, you also forgot to initialized list
. 正如@Fildor在评论中指出的那样,您还忘记了初始化
list
。 Instead of initializing to null
list you currently have, you should have something down the lines of List<Type> list = new LinkedList<>();
而不是初始化为当前拥有的
null
列表,而应该在List<Type> list = new LinkedList<>();
. 。
You have mention the reference but you have to use the Class there :- 您已经提到了引用,但必须在其中使用Class:
public static List<Type> getProtocolls(Class clazz, Transaction trx) {
Iterator<Type> iterator = trx.getContext().getProtocolls()
List<Type> list = null;
while (iterator.hasNext()) {
if (iterator.next() instanceof Class ) {
list.add(iterator.next())
}
}
return list;
}
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