@Test

    public void test() {

        Integer i3 =128;

        Integer i4=128;

        boolean integerGT127=i3==i4;
        //false

        System.out.println("Integer 128==128"+integerGT127);

        Integer i1 =127;

        Integer i2=127;

        boolean integerLt127=i1==i2;
　　　　　　//true

        System.out.println("Integer 127==127"+integerLt127);

        Integer i5 = 5001;

        boolean unBoxingInteger=i5 > 500 && i5 < 1000;

        System.out.println("Integer unbox "+integerLt127);

        Integer i6=500,i7=1000;

        boolean unBoxingInteger2=i5.compareTo(i6)>0&&i5.compareTo(i7)<0;

        System.out.println("Integer compare "+integerLt127);

        //装箱 将 10（int）转换为了 Integer

        Integer i9=10;

        //拆箱 将i9（Integer）转换为了int

        int i10=i9; 
 

    }

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 =

                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() {}

    }

 public static Integer valueOf(int i) {

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

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

        return new Integer(i);

    }

Integer.valueOf(10);
Double.valueOf(23.00);
Boolean.valueOf(true);
Boolean b1=true,b2=true;
//true  Boolean.valueOf(true);
// final修饰的对象只能指向唯一一个对象，不可以再将它指向其他对象，而static final修饰的对象则可以使一个常量真正做到不被修改
System.out.println(b1==b2);
// true  Boolean.valueOf(true);
System.out.println(b1.equals(b2));
Double d1=20.00,d2=20.00;
// false   Double.valueOf
System.out.println(d1==d2);
//true
System.out.println(d1.equals(d2));

public static Boolean valueOf(boolean b) {

        return (b ? TRUE : FALSE);

    }

    /**

     * The {@code Boolean} object corresponding to the primitive

     * value {@code true}.

     */

    public static final Boolean TRUE = new Boolean(true);

    /**

     * The {@code Boolean} object corresponding to the primitive

     * value {@code false}.

     */

    public static final Boolean FALSE = new Boolean(false);

    public static Double valueOf(double d) {

        return new Double(d);

    }