Java：死码消除(Java: Dead code elimination)

 我想知道Java如何处理以下情况： 
 
 假设我有一个名为Debug的类，如下所示： 
 
public class Debug 
{
    private static final boolean isAssertEnabled = true;

    public static void assertTrue(boolean b, String errorMessage) {
        if (isAssertEnabled) {
            if (!b) {
                throw new RuntimeException(errorMessage);
            }
        }
    }
}
 
 并假设我的代码有一个如下所示的调用： 
 
...
Debug.assertTrue((x + y != z) && (v - u > w), "Some error message");
....
 
 我有几个问题： 
 
 
 
 如果isAssertEnabled标志设置为false ，那么对Debug.assertTrue的整个调用是否会被编译出来？ 请注意，检查isAssertEnabled == true是否仅在函数调用后进行。 
 
 
 如果整个调用都被编译出来，那么这是否意味着对布尔表达式的求值被编译出来？ 如果没有任何评价，那将是一种浪费。 
 
 
 感谢您的帮助！ 

I'd like to know how Java would handle the following scenario:
 
Suppose I have a class called Debug, which looks like this:
 
public class Debug 
{
    private static final boolean isAssertEnabled = true;

    public static void assertTrue(boolean b, String errorMessage) {
        if (isAssertEnabled) {
            if (!b) {
                throw new RuntimeException(errorMessage);
            }
        }
    }
}
 
and suppose my code has a call that looks something like this:
 
...
Debug.assertTrue((x + y != z) && (v - u > w), "Some error message");
....
 
I have a few questions: 
 
 
 
If the isAssertEnabled flag is set to false, will the whole call to Debug.assertTrue be compiled out? Please note that the check if isAssertEnabled == true is only made inside the function after it was called. 
 
 
If the whole call does get compiled out, does that also mean that the evaluation of the boolean expression is compiled out? Would be a waste to evaluate that expression for nothing. 
 
 
Thanks for you help!

原文：https://stackoverflow.com/questions/4756462