Java Reference
In-Depth Information
The
String
classrepresentsastringasasequenceofcharacters.Becauseinstances
ofthisclassareimmutable,Javaprovides
StringBuffer
and
StringBuilder
for
buildingastringmoreefficiently.Theformerclasscanbeusedinamultithreadedcon-
text, whereas the latter class is more performant.
The
System
classprovidesaccesstostandardinput,standardoutput,standarderror,
and other system-oriented resources. For example,
System
provides the
array-
copy()
method as the fastest portable way to copy one array to another.
Javasupportsthreadsviaitslow-levelThreadingAPI.ThisAPIconsistsofoneinter-
face (
Runnable
) and four classes (
Thread
,
ThreadGroup
,
ThreadLocal
, and
InheritableThreadLocal
).
Throughout its execution, each thread is isolated from other threads because it has
beengivenitsownmethod-callstack.However,threadscanstillinterferewitheachoth-
erwhentheyaccessandmanipulateshareddata.Thisinterferencecancorrupttheshared
data, and this corruption can cause an application to fail. Java provides a thread-syn-
chronization mechanism to prevent this interference.
Money must never be represented by floating-point and double precision floating-
pointvariablesbecausenotallmonetaryvaluescanberepresentedexactly.Incontrast,
the
BigDecimal
class lets you accurately represent and manipulate these values.
BigDecimal
reliesonthe
BigInteger
classforrepresentingitsunscaledvalue.
A
BigInteger
instancedescribesanintegervaluethatcanbeofarbitrarylength(sub-
ject to the limits of the JVM's memory).
This chapter briefly referred to the Collections Framework while introducing the
Primitive Type Wrapper Class API.
Chapter 5
introduces you to this broad utility API
for collecting objects.
