考虑清单：
def list = [1, 2, 3]
如果我使用
list.getAt(0)
或
list.get(0)
两者都会给出相同的输出
但getAt（）和get（）之间是否存在差异？
答案 0 :(得分：14)
支持列表的下标运算符。
def list = [2, "a", 5.3]
assert list[1] == "a"
所以没有区别，但getAt()是允许Groovy代码使用list[1]代替list.get(1)的方法
有关运算符重载的工作原理，请参阅http://groovy.codehaus.org/Operator+Overloading。
答案 1 :(得分：7)
文档没有很好地解释这一点，但实际上我的测试中的差异似乎是getAt(i)在引用列表中实际不存在的索引时将返回null，而get(i)将返回class BookView: UIScrollView {
var bookMarkup: NSAttributedString!
private let layoutManager = NSLayoutManager()
override func layoutSubviews() {
super.layoutSubviews()
if layoutManager.textContainers.count == 0 {
buildFrames()
}
}
func buildFrames() {
let textStorage = NSTextStorage(attributedString: bookMarkup)
textStorage.addLayoutManager(layoutManager)
var range = NSMakeRange(0, 0)
var containerIndex = 0
while NSMaxRange(range) < layoutManager.numberOfGlyphs {
let textViewRect = frameForViewAtIndex(containerIndex)
let containerSize = CGSizeMake(CGRectGetWidth(textViewRect), CGRectGetHeight(textViewRect) - 16) //UITextView adds an 8 margin above and below the container so we take that into consideration here with the 16. heightTracksTextView causes a performance hit when adding multiple containers... so we don't do that instead
let textContainer = NSTextContainer(size: containerSize)
layoutManager.addTextContainer(textContainer)
let textView = UITextView(frame: textViewRect, textContainer: textContainer)
addSubview(textView)
containerIndex++
range = layoutManager.glyphRangeForTextContainer(textContainer)
}
contentSize = CGSize(width: CGRectGetWidth(bounds) / 2 * CGFloat(containerIndex), height: CGRectGetHeight(bounds))
pagingEnabled = true
}
private func frameForViewAtIndex(index: Int) -> CGRect {
var textViewRect = CGRect(origin: CGPointZero, size: CGSize(width: CGRectGetWidth(bounds)/2, height: CGRectGetHeight(bounds)))
textViewRect = CGRectInset(textViewRect, 10, 20)
textViewRect = CGRectOffset(textViewRect, CGRectGetWidth(bounds) / 2 * CGFloat(index), 0)
return textViewRect
}
}
当传入不在列表中的索引时，方法将抛出 IndexOutOfBoundsException ，就像普通的旧Java一样。