Java basic frequency interval data type of packaging data cache

A, Java basic data type of packaging: Integer, Long, Double, Float, Boolean, Byte, Short, Character.

Second, the high-frequency buffer

• Double and Float in which no cache, there are other types of high-frequency buffer zone. High-frequency range of the cache buffer section is:
  Boolean: using static final, it will return a static value
  Byte: 127 -128 ~
  Short: 127 -128 ~
  Character: 0 ~ 127
  Long: 127 -128 ~
  Integer: -128 ~ 127

• If the value is used for packaging in this buffer zone, the complex will be the direct use of an existing object, the cache values outside the interval will be re-generated on the heap. Therefore, in determining whether or not to use equal, "==", with equals, otherwise, the following occurs:
  Integer I1 = 127;
  Integer i2 = 127;
  I1 i2 == -> to true

  Integer i3 = 128;
  Integer i4 = 128;
  i3 == i4 ->false

• Integer modified cache is the only one range of packaging. Add parameters in VM options: -XX: AutoBoxCacheMax = 555 maximum range is about to change the cache 555.