java中整數常量池(-128~127)上限如何調整？

眾所周知：java中Integer有一個常量池范圍-128~127

Integer a = 500, b = 500;
System.out.println(a == b);//false
a = 100;
b = 100;
System.out.println(a == b);//true

相信也有一部分人在面試時，也被問到過這個問題，但是如果面試官繼續追問：如果我想讓　

Integer a = 500, b = 500;
System.out.println(a == b);

也返回true，該怎么做？沒准備的同學，可能會一時被問住，其實答案就在java.lang.Integer.IntegerCache 這個類的源碼上

    /**
     * Cache to support the object identity semantics of autoboxing for values between
     * -128 and 127 (inclusive) as required by JLS.
     *
     * The cache is initialized on first usage.  The size of the cache
     * may be controlled by the {@code -XX:AutoBoxCacheMax=<size>} option.
     * During VM initialization, java.lang.Integer.IntegerCache.high property
     * may be set and saved in the private system properties in the
     * sun.misc.VM class.
     */

    private static class IntegerCache {
       // ...
    }

這個類的注釋上，已經明細說明：

-XX:AutoBoxCacheMax=<size>
-Djava.lang.Integer.IntegerCache.high=<size>

這2個參數都可以控制上限。