org.apache.el.lang
Class ELSupport

java.lang.Object
  org.apache.el.lang.ELSupport

Direct Known Subclasses:

SimpleNode

public class ELSupport
extends Object

A helper class that implements the EL Specification

Version:

$Id: ELSupport.java 1244574 2012-02-15 16:30:37Z markt $

Author:

Jacob Hookom [jacob@hookom.net]

Constructor Summary

ELSupport()

Method Summary

static Boolean	coerceToBoolean(Object obj) Convert an object to Boolean.
static Character	coerceToCharacter(Object obj)
static Enum<?>	coerceToEnum(Object obj, Class type)
protected static Number	coerceToNumber(Number number, Class<?> type)
static Number	coerceToNumber(Object obj, Class<?> type)
protected static Number	coerceToNumber(String val, Class<?> type)
static String	coerceToString(Object obj) Coerce an object to a string
static Object	coerceToType(Object obj, Class<?> type)
static int	compare(Object obj0, Object obj1) Compare two objects, after coercing to the same type if appropriate.
static boolean	equals(Object obj0, Object obj1) Compare two objects for equality, after coercing to the same type if appropriate.
static boolean	isBigDecimalOp(Object obj0, Object obj1)
static boolean	isBigIntegerOp(Object obj0, Object obj1)
static boolean	isDoubleOp(Object obj0, Object obj1)
static boolean	isLongOp(Object obj0, Object obj1)
static boolean	isStringFloat(String str)

Methods inherited from class java.lang.Object

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

Constructor Detail

ELSupport

public ELSupport()

Method Detail

compare

public static final int compare(Object obj0,
                                Object obj1)
                         throws ELException

Compare two objects, after coercing to the same type if appropriate. If the objects are identical, or they are equal according to equals(Object, Object) then return 0. If either object is a BigDecimal, then coerce both to BigDecimal first. Similarly for Double(Float), BigInteger, and Long(Integer, Char, Short, Byte). Otherwise, check that the first object is an instance of Comparable, and compare against the second object. If that is null, return 1, otherwise return the result of comparing against the second object. Similarly, if the second object is Comparable, if the first is null, return -1, else return the result of comparing against the first object. A null object is considered as:

• ZERO when compared with Numbers
• the empty string for String compares
• Otherwise null is considered to be lower than anything else.

Parameters:

obj0 - first object

obj1 - second object

Returns:

-1, 0, or 1 if this object is less than, equal to, or greater than val.

Throws:

ELException - if neither object is Comparable

ClassCastException - if the objects are not mutually comparable

equals

public static final boolean equals(Object obj0,
                                   Object obj1)
                            throws ELException

Compare two objects for equality, after coercing to the same type if appropriate. If the objects are identical (including both null) return true. If either object is null, return false. If either object is Boolean, coerce both to Boolean and check equality. Similarly for Enum, String, BigDecimal, Double(Float), Long(Integer, Short, Byte, Character) Otherwise default to using Object.equals().

Parameters:

obj0 - the first object

obj1 - the second object

Returns:

true if the objects are equal

Throws:

ELException

coerceToEnum

public static final Enum<?> coerceToEnum(Object obj,
                                         Class type)

coerceToBoolean

public static final Boolean coerceToBoolean(Object obj)
                                     throws ELException

Convert an object to Boolean. Null and empty string are false.

Parameters:

obj - the object to convert

Returns:

the Boolean value of the object

Throws:

ELException - if object is not Boolean or String

coerceToCharacter

public static final Character coerceToCharacter(Object obj)
                                         throws ELException

Throws:

ELException

coerceToNumber

protected static final Number coerceToNumber(Number number,
                                             Class<?> type)
                                      throws ELException

Throws:

ELException

coerceToNumber

public static final Number coerceToNumber(Object obj,
                                          Class<?> type)
                                   throws ELException

Throws:

ELException

coerceToNumber

protected static final Number coerceToNumber(String val,
                                             Class<?> type)
                                      throws ELException

Throws:

ELException

coerceToString

public static final String coerceToString(Object obj)

Coerce an object to a string

Parameters:

obj -

Returns:

the String value of the object

coerceToType

public static final Object coerceToType(Object obj,
                                        Class<?> type)
                                 throws ELException

Throws:

ELException

isBigDecimalOp

public static final boolean isBigDecimalOp(Object obj0,
                                           Object obj1)

isBigIntegerOp

public static final boolean isBigIntegerOp(Object obj0,
                                           Object obj1)

isDoubleOp

public static final boolean isDoubleOp(Object obj0,
                                       Object obj1)

isLongOp

public static final boolean isLongOp(Object obj0,
                                     Object obj1)

isStringFloat

public static final boolean isStringFloat(String str)