提问人:Angge 提问时间:6/26/2021 更新时间:6/26/2021 访问量:1187
if else 语句中的多个布尔值在 Java 中始终为 false
Multiple boolean values in if else statement is always false in Java
问:
我坚持使用这种方法,因为 if else 条件说
Condition usersInSales && usersInPayments is always false
Condition usersInSales && usersInLoans is always false
Condition usersInPayments && usersInLoans is always false
我尝试了不同的条件组合并添加了错误值以尝试解决它,但没有帮助。请问我能帮忙吗?提前致谢
private List<UserResource> usersFilteredByDepartment(List<UserResource> users, boolean usersInSales, boolean usersInPayments, boolean usersInLoans) {
if (usersInSales) {
return getUsersInSales(users);
} else if (usersInPayments) {
return getUsersInPayments(users);
} else if (usersInLoans) {
return getUsersInLoans(users);
} else if (usersInSales && usersInPayments) {
return Stream.concat(getUsersInSales(users).stream(), getUsersInPayments(users).stream()).distinct().collect(Collectors.toList());
} else if (usersInSales && usersInLoans) {
return Stream.concat(getUsersInSales(users).stream(), getUsersInLoans(users).stream()).distinct().collect(Collectors.toList());
} else if (usersInPayments && usersInLoans) {
return Stream.concat(getUsersInPayments(users).stream(), getUsersInLoans(users).stream()).distinct().collect(Collectors.toList());
} else return users;
}
答:
1赞
Mark Rotteveel
6/26/2021
#1
考虑你的逻辑:你首先检查,如果它是真的,则返回。然后你检查并返回它是否属实。因此,当您检查时,两者都将是假的,因为您已经处理了其中任何一个为真的情况。usersInSales
usersInPayments
usersInSales && usersInPayments
您需要更改逻辑,以便以累加而不是独占方式处理条件。
3赞
Panagiotis Bougioukos
6/26/2021
#2
if (usersInSales) {
return getUsersInSales(users);
} else if (usersInPayments) { ---> You get here when userInSales = false
return getUsersInPayments(users);
} else if (usersInLoans) { --> You get here when usersInSales = false && usersInPayments = false
return getUsersInLoans(users);
} else if () { --> You get here when usersInSales = false && usersInPayments = false && usersInLoans = false. No use in comparing what you compare here. It will be always false as it reports to
}
希望你现在能想出路
您可以尝试首先检查最具体的约束,然后最终转到更一般的约束。
if (usersInSales && usersInPayments) {
return Stream.concat(getUsersInSales(users).stream(), getUsersInPayments(users).stream()).distinct().collect(Collectors.toList());
} else if (usersInSales && usersInLoans) {
return Stream.concat(getUsersInSales(users).stream(), getUsersInLoans(users).stream()).distinct().collect(Collectors.toList());
} else if (usersInPayments && usersInLoans) {
return Stream.concat(getUsersInPayments(users).stream(), getUsersInLoans(users).stream()).distinct().collect(Collectors.toList());
} else if (usersInSales) {
return getUsersInSales(users);
} else if (usersInPayments) {
return getUsersInPayments(users);
} else if (usersInLoans) {
return getUsersInLoans(users);
} else return users;
但是,检查您的工作流程 IMO 如果没有所有这些 if,else 检查,您的方法会更有意义。这就足够了
private List<UserResource> usersFilteredByDepartment(List<UserResource> users, boolean usersInSales, boolean usersInPayments, boolean usersInLoans) {
return Stream.concat(
usersInPayments? getUsersInPayments(users).stream(): Stream.empty(),
usersInLoans? getUsersInLoans(users).stream(): Stream.empty(),
usersInSales? getUsersInSales(users).stream(): Stream.empty()
).distinct().collect(Collectors.toList());
}
1赞
DEV
6/26/2021
#3
您的最后 3 个条件将永远不会运行。因为你的前 3 个条件之一已经成立。要解决此问题,您需要颠倒条件的顺序,请尝试以下操作:
if (usersInSales && usersInPayments) {
} else if (usersInSales && usersInLoans) {
} else if (usersInPayments && usersInLoans) {
} else if (usersInSales ) {
} else if ( usersInLoans) {
} else if (usersInLoans) {
} else return users;
3赞
Alan
6/26/2021
#4
您有两种解决方案。
重新排序您的条件,正如其他人所展示的那样。在你的代码中,当你命中你已经处理过一半为真的情况时,你已经处理过了。(两个子句)比单个子句更具限制性。
&&
&&
或者,将双子句放在前面的 ifs 中。
if (usersInSales) { return getUsersInSales(users); } else if (usersInPayments) { return getUsersInPayments(users); } else if (usersInLoans) { return getUsersInLoans(users); } else if (usersInSales && usersInPayments) { return Stream.concat(getUsersInSales(users).stream(), getUsersInPayments(users).stream()).distinct().collect(Collectors.toList()); } else if (usersInSales && usersInLoans) {...
成为
if (usersInSales) {
if (usersInPayments) { // Nested if is like && operator.
return Stream.concat(getUsersInSales(users).stream(), getUsersInPayments(users).stream()).distinct().collect(Collectors.toList());
} else {
return getUsersInSales(users);
}
} else if (usersInPayments) { ...
这更有效率,我认为通常更可取。
评论
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usersInSales && usersInPayments
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if