Integeter127 and 128

1  PackageCom.hangao.basic;2 3 /**4  * @authorHangao [email protected]5  *6  */7  Public classTestint {8      Public Static voidMain (string[] args) {9Integer Ie1 = 127;TenInteger Ie2 = 127; OneSystem.out.println ("Integer 127==127:" + (Ie1 = = ie2));//Integer 127==127:true A          -Integer ie3 =NewInteger (127); -Integer ie4 =NewInteger (127); theSystem.out.println ("New Integer 127==127:" + (ie3 = = ie4));//New Integer 127==127:false -          -Integer IE5 = 128; -Integer IE6 = 128; +System.out.println ("Integer 128==128:" + (IE5 = = IE6));//Integer 128==128:false -          +Integer IE7 =NewInteger (128); AInteger IE8 =NewInteger (128); atSystem.out.println ("New Integer 128==128:" + (IE7 = = IE8));//New Integer 128==128:false -          - Analysis (); -     } -  -     Private Static voidAnalysis () { inInteger IE0 = 127; - System.out.println (IE0); to         /*L0 + linenumber 5 L0 - Bipush 127 the invokestatic java/lang/integer.valueof (I) Ljava/lang/integer; * ASTORE 1*/ $         /*from the bytecode file you can see that there is an auto-boxing action*/Panax Notoginseng          -         /*Public static Integer valueOf (int i) { the if (i >= integercache.low && i <= integercache.high) + return integercache.cache[i + (-integercache.low)]; A return new Integer (i); the         }*/ +         /*The boxing process of the Integeter class can be seen in the int value between (-128-127) from the Integeter source code. - it actually returns the object inside the Integercache cache[] array.*/ $          $         /*private Static class Integercache { - static final int low = -128; - static final int high; the static final Integer cache[]; - Wuyi Static { the //High value is configured by property - int h = 127; Wu String integercachehighpropvalue = - sun.misc.VM.getSavedProperty ("Java.lang.Integer.IntegerCache.high"); About if (integercachehighpropvalue! = null) { $ try { - int i = Integer.parseint (integercachehighpropvalue); - i = Math.max (i, 127); - //Maximum array size is Integer.max_value A h = math.min (i, Integer.max_value-(-low)-1); + } catch (NumberFormatException nfe) { the //If The property cannot is parsed into an int, ignore it. -                     } $                 } the High = h; the  the cache = new integer[(high-low) + 1]; the int j = Low; - for (int k = 0; k < cache.length; k++) in Cache[k] = new Integer (j + +); the  the //Range [ -128, 127] must be interned (JLS7 5.1.7) About assert Integercache.high >= 127; the             } the  the Private Integercache () {} +         }*/ -         /*Integercache is an integer inner class that initializes an array of integer classes that correspond to all int values created (-128-127) when loaded by the JDK . the you can take it from the inside when you use it.*/Bayi     } the}

Integeter127 and 128