Question

我正在尝试编写以下条件：

if(javaList.contains("aaa")||javaList.contains("abc")||javaList.contains("abc")) {
    //do something
}

我怎样才能做得更好？

Answer 1

在contains上运行Set通常比在List上运行效率更高。因此，我建议您为要测试的元素创建一个Set，然后在List上进行流传输以查看其任何元素是否匹配：

怎么样：

if (javaList.stream().anyMatch(e -> Set.of("aaa","abc","def").contains(e)))

Answer 2

如果您使用的是Java 8及更高版本，则可以使用以下代码：

if (javaList.stream().anyMatch(l -> l.matches("aaa|xyz|abc")))

您可以使用.matches()并传入由 OR 符号分隔的字符串。 .matches()接受一个 String ，表示为 regex 。

Answer 3

转换为设置并检查交点。

(declare-sort Eff) ; type of an effect
(declare-sort Ssn) ; type of a session
(declare-sort Oper) ; type of an operation
(declare-fun seqno (Eff) Int) ; each effect has a seqno
(declare-fun ssn (Eff) Ssn)
(declare-fun oper (Eff) Oper)
(declare-fun so (Eff Eff) Bool) ; session order
(declare-fun vis (Eff Eff) Bool) ; visibility
(declare-fun hb (Eff Eff) Bool) ; happens-before
(declare-fun NOP () Oper)
(declare-fun District_IncNextOID () Oper)
(declare-fun District_Add () Oper)
(declare-fun District_Get () Oper)
(declare-fun E2 () Eff)
(declare-fun E1 () Eff)
(declare-fun E0 () Eff)
;;
;; Cardinality constraints
;;
(assert (forall ((a0 Eff))
  (or (= a0 E0)
      (= a0 E1)
      (= a0 E2)
      )))
(assert (distinct E0 E1 E2 ))
(assert (forall ((a0 Oper))
  (or (= a0 District_Get)
      (= a0 District_Add)
      (= a0 District_IncNextOID)
      (= a0 NOP))))
(assert (distinct 
          District_Get
          District_Add
          District_IncNextOID
          NOP))
;;
;; Axioms
;;
;; session order relates sequential effects in 
;; the same session
(assert (forall ((a0 Eff) (a1 Eff))
  (let ((a!1 (and (not (= (oper a0) NOP))
                  (not (= (oper a1) NOP))
                  (= (ssn a0) (ssn a1))
                  (< (seqno a0) (seqno a1)))))
    (= (so a0 a1) a!1))))
;; session-order is transitive
(assert (forall ((a0 Eff) (a1 Eff) (a2 Eff))
  (=> (and (so a0 a1) (so a1 a2)) (so a0 a2))))
;; visibility is irreflexive
(assert (forall ((a0 Eff)) (not (vis a0 a0))))
;; visibility is anti-symmetric
(assert (forall ((a0 Eff) (a1 Eff)) 
  (=> (and (vis a0 a1) (vis a1 a0)) (= a0 a1))))
;; happens-before is (so ∪ vis)
(assert (forall ((a0 Eff) (a1 Eff)) 
  (=> (or (vis a0 a1) (so a0 a1)) (hb a0 a1))))
;; happens-before is transitive
(assert (forall ((a0 Eff) (a1 Eff) (a2 Eff))
  (=> (and (hb a0 a1) (hb a1 a2)) (hb a0 a2))))
;; happens-before is irreflexive
(assert (forall ((a0 Eff)) (not (hb a0 a0))))
;;
;; Check
;;
(assert (so E1 E2))
;(assert (not (hb E1 E2)))
(check-sat)
(get-model)
(eval (so E1 E2)) ; returns true
(eval (hb E1 E2)) ; returns false. Why?

检查size> 0，然后您还可以查看其中包含的东西，这很有趣。

如何方便地检查列表中是否包含多个元素？

3 个答案: