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Integer i2 = 56;

Integer i3 = 129;

Integer i4 = 129;

System.out.println(i1 == i2);

System.out.println(i3 == i4);

if (i >= IntegerCache.low && i <= IntegerCache.high)

return IntegerCache.cache[i + (-IntegerCache.low)];

return new Integer(i);

}

* 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 {

static final int low = -128;

static final int high;

static final Integer cache[];

static {

// high value may be configured by property

int h = 127;

String integerCacheHighPropValue =

sun.misc.VM.getSavedProperty(“java.lang.Integer.IntegerCache.high”);

if (integerCacheHighPropValue != null) {

try {

int i = parseInt(integerCacheHighPropValue);

i = Math.max(i, 127);

// Maximum array size is Integer.MAX_VALUE

h = Math.min(i, Integer.MAX_VALUE – (-low) -1);

} catch( NumberFormatException nfe) {

// If the property cannot be parsed into an int, ignore it.

}

}

high = h;

cache = new Integer[(high – low) + 1];

int j = low;

for(int k = 0; k < cache.length; k++)

cache[k] = new Integer(j++);

// range [-128, 127] must be interned (JLS7 5.1.7)

assert IntegerCache.high >= 127;

}

private IntegerCache() {}

}