org.apache.hadoop.util

Class StringInterner

java.lang.Object

org.apache.hadoop.util.StringInterner

@InterfaceAudience.Public
 @InterfaceStability.Stable
public class StringInterner
extends Object

Provides string interning utility methods. For weak interning, we use the standard String.intern() call, that performs very well (no problems with PermGen overflowing, etc.) starting from JDK 7.

Constructor Summary

Constructors

Constructor and Description
StringInterner()

Method Summary

Modifier and Type	Method and Description
static String[]	internStringsInArray(String[] strings) Interns all the strings in the given array in place, returning the same array.
static String	strongIntern(String sample) Interns and returns a reference to the representative instance for any of a collection of string instances that are equal to each other.
static String	weakIntern(String sample) Interns and returns a reference to the representative instance for any of a collection of string instances that are equal to each other.

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Constructor Detail

StringInterner

public StringInterner()

Method Detail

strongIntern

public static String strongIntern(String sample)

Interns and returns a reference to the representative instance for any of a collection of string instances that are equal to each other. Retains strong reference to the instance, thus preventing it from being garbage-collected.

Parameters:

sample - string instance to be interned

Returns:

strong reference to interned string instance

weakIntern

public static String weakIntern(String sample)

Interns and returns a reference to the representative instance for any of a collection of string instances that are equal to each other. Retains weak reference to the instance, and so does not prevent it from being garbage-collected.

Parameters:

sample - string instance to be interned

Returns:

weak reference to interned string instance

internStringsInArray

public static String[] internStringsInArray(String[] strings)

Interns all the strings in the given array in place, returning the same array.

Parameters:

strings - strings.

Returns:

internStringsInArray.