Groovy 条件语句

在groovy中支持如下 条件语句

1:if/else if/else

if ( ... ) {
    ...
} else if (...) {
    ...
} else {
    ...
}

2:switch / case

Groovy中的switch语句向后兼容Java代码

Switch supports the following kinds of comparisons:

• Class case values match if the switch value is an instance of the class

• Regular expression case values match if the toString() representation of the switch value matches the regex

• Collection case values match if the switch value is contained in the collection. This also includes ranges (since they are Lists)

• Closure case values match if the calling the closure returns a result which is true according to the Groovy truth

• If none of the above are used then the case value matches if the case value equals the switch value

switch值是类的实例，则类用例值匹配

如果开关值的toString()表示形式与正则表达式匹配，则正则表达式用例值匹配。其实就是支持正则表达式的方式

switch支持集合

支持闭包：调用闭包返回的结果根据Groovy事实为真，则闭包用例值匹配

如果上面的值都没有使用，那么如果case值等于switch值，则case值将匹配

def x = 1.23
def result = ""

switch ( x ) {
    case "foo":
        result = "found foo"
        // lets fall through

    case "bar":
        result += "bar"

    case [4, 5, 6, 'inList']:
        result = "list"
        break

    case 12..30:
        result = "range"
        break

    case Integer:
        result = "integer"
        break

    case Number:
        result = "number"
        break

    case ~/fo*/: // toString() representation of x matches the pattern?
        result = "foo regex"
        break

    case { it < 0 }: // or { x < 0 }
        result = "negative"
        break

    default:
        result = "default"
}