public static Integer valueOf(int i) {
        if (i >= cache_low && i <= cache_high) { // must cache
            return cache[i - cache_low];
        } else {
            return new Integer(i);
        }
    }
Returns a <tt>Integer</tt> instance representing the specified <tt>int</tt> value. If a new <tt>Integer</tt>
instance is not required, this method should generally be used in preference to the constructor
{@link #Integer(int)}, as this method is likely to yield significantly better space and time performance by
caching frequently requested values.

@param i an <code>int</code> value.
@return a <tt>Integer</tt> instance representing <tt>i</tt>.
@since 1.5
shared/common/src/main/java/com/alibaba/otter/shared/common/utils/sizeof/ObjectProfiler.java