如何在閉包和方法之間共享參數（雙向傳遞和返回），如下面的常規代碼所示？

Question

Groovy代碼：如何傳遞和返回參數或值

def method (int a, Closure c) {
    Query q = new Query()
    c.delegate = q
    c()
    //label 1: pass a to label 2 and get str from there 
}
class Query
{
    void key (String str) {
        //label 2: return str and get a to method label 1.
    }
}
method(5) {
    key "got"
}

如何在上面顯示的常規代碼中訪問兩個標簽。

我不知道如何在此閉包內使用某些鍵，例如.call() return 。

更新1：

def method (int a, Closure c) {
    Query q = new Query()
    c.delegate = q
    c.call(a)
    def str = q.str
    println str
}
class Query
{
    def str
    def a
    void key (String str) {
        this.str = str
        this.a=a
        println a
    }
}
method(5) {
    key "got"
}

實際輸出：

null
got

預期產量：

5
got

如何解決呢？

Answer 1

怎么樣

def method (int a, Closure c) {
    Query q = new Query()
    q.a = a
    c.delegate = q
    c.call()
    def str = q.str
    println str
}
class Query
{
    def str
    def a
    void key (String str) {
        this.str = str
        println a
    }
}
method(5) {
    key "got"
}