在Java 6中编译，在7中运行 - 如何指定useLegacyMergeSort？ [英] Compile in Java 6, run in 7 - how to specify useLegacyMergeSort?

问题描述

我想知道我是否在Java 6中编译，但有人在Java 7上运行该程序，是否会使用Java 6或7版本的Arrays.sort？

I'm wondering if I compile in Java 6, but someone runs the program on Java 7, will the Java 6 or 7 version of Arrays.sort be used?

这很重要，因为新的mergesort会抛出IllegalArgumentException，旧的则不会抛出（参见比较方法违反了它的一般合同！仅限Java 7 ）

It's important because the new mergesort throws an IllegalArgumentException, and the old one doesn't (see Comparison method violates its general contract! Java 7 only)

现在，可以使用Arrays.useLegacyMergeSort在Java 7中编译，但很明显，该标志不适用于Java 6 - 我们希望在Mac OS Snow Leopard（使用6）上兼容。

Now, it's possible to compile in Java 7 using Arrays.useLegacyMergeSort, but obviously that flag isn't available for Java 6 - and we want to be compatible on Mac OS Snow Leopard (which uses 6).

出于某种原因（请参阅 http://madbean.com/2006/target14/ ）-target编译器标志没有似乎产生兼容的代码，所以我们宁愿用Java 6编译。

For some reason (see http://madbean.com/2006/target14/) the -target compiler flag doesn't seem to produce compatible code, so we'd rather compile in Java 6.

有什么建议吗？

推荐答案

尝试设置系统属性

java -Djava.util.Arrays.useLegacyMergeSort = true ...

请注意，它不是来自Arrays公共API，而是来自src

Note that it's not from Arrays public API but from src

   /**
     * Old merge sort implementation can be selected (for
     * compatibility with broken comparators) using a system property.
     * Cannot be a static boolean in the enclosing class due to
     * circular dependencies. To be removed in a future release.
     */
    static final class LegacyMergeSort {
        private static final boolean userRequested =
            java.security.AccessController.doPrivileged(
                new sun.security.action.GetBooleanAction(
                    "java.util.Arrays.useLegacyMergeSort")).booleanValue();
    }

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