Java OCA考试备考：if语句使用continue的编译疑问

Hey there! Let's clear up this confusion you're having—it's a common point that trips up many OCA candidates, so great catch on noticing the discrepancy!

First, let's unpack what Sybex's Table 2.5 actually means #

The note says "if语句不允许使用break、continue语句" (if statements don't allow break/continue), but this is referring to using break/continue to target the if statement itself. Since if is a conditional branching structure (not a loop or switch), there's no structure for break/continue to interrupt here. For example, this code would fail to compile:

public class BadExample {
    public static void main(String[] args) {
        int x = 5;
        if (x > 0) {
            break; // Compile error: no enclosing loop or switch statement
        }
    }
}

Here, break has no loop or switch to act on—this is the scenario Sybex is warning about.

Now let's look at your sample code #

Your code has continue nested inside an if, but crucially, that if is itself inside a while loop (the inner while(y>0) loop). The continue here doesn't target the if statement—it targets the nearest enclosing loop (the inner while loop).

Let's break down how this works:

• When x < 2 is true, continue skips the rest of the inner loop's iteration (so x--, y--, and the System.out.println don't run) and jumps back to the start of the inner while(y>0) condition check.
• Since continue is clearly associated with a valid loop structure, the compiler has no issue with this code.

Key Takeaway for OCA #

Remember: break and continue only require an enclosing loop or switch statement to be valid. They can be nested inside if blocks, as long as they're still within a loop/switch that they can act on. The Sybex note is just warning you not to use them without that enclosing loop/switch, or to try using them to control the if itself.

内容的提问来源于stack exchange，提问作者Sam