使用递增运算符设置语句参数值时的求值顺序

Question

这是设置先前生成的准备语句参数的正确语法吗？哪个先出现，是给变量i加1，还是变量在设置参数时的用法？

int i=1;
for (TagInfo tag : scannedTags){
    //Pull the tag from the dbo.Tags table that matches the SiteID and TagOffSet values of the current tag in the alarm_tags list 
    //Set parameters for the prepared statement
    dbStmtTag.setInt(i++, tag.getSiteID());
    dbStmtTag.setInt(i++, tag.getTagOffset());
}

如果操作顺序是值先递增，我假设我可以在设置参数后只加1。我只是为了代码简洁起见。

Answer 1

[To test the behaviour of i++ for myself] I'd have to write an entire test application that talks to a test database, which I would need to create.

废话。您需要做的就是...

public static void main(String[] args) {
    try {
        int i = 1;
        System.out.printf("i is %d%n", i);
        System.out.printf("i++ returned %d%n", i++);
        System.out.printf("i is now %d%n", i);
    } catch (Exception e) {
        e.printStackTrace(System.err);
    }
}

... 产生 ...

i is 1
i++ returned 1
i is now 2

使用递增运算符设置语句参数值时的求值顺序

Order of evaluation when using an increment operator to set the value of statement parameters

parameters

iterator

jdbc

operator-precedence

java-8