Class ELSupport

java.lang.Object
org.apache.el.lang.ELSupport
public class ELSupport extends Object
A helper class that implements the EL Specification
Author:
Jacob Hookom [jacob@hookom.net]

  • Field Details

    • COERCE_TO_ZERO

      protected static final boolean COERCE_TO_ZERO

  • Method Details

    • compare

      public static final int compare(ELContext ctx, 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(ELContext, 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:
      ctx - the context in which this comparison is taking place
      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(ELContext ctx, 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:
      ctx - the context in which this equality test is taking place
      obj0 - the first object
      obj1 - the second object
      Returns:
      true if the objects are equal
      Throws:
      ELException - if one of the coercion fails

    • coerceToEnum

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

    • coerceToBoolean

      public static final Boolean coerceToBoolean(ELContext ctx, Object obj, boolean primitive) throws ELException
      Convert an object to Boolean. Null and empty string are false.
      Parameters:
      ctx - the context in which this conversion is taking place
      obj - the object to convert
      primitive - is the target a primitive in which case coercion to null is not permitted
      Returns:
      the Boolean value of the object
      Throws:
      ELException - if object is not Boolean or String

    • coerceToNumber

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

    • coerceToNumber

      public static final Number coerceToNumber(ELContext ctx, 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(ELContext ctx, Object obj)
      Coerce an object to a string.
      Parameters:
      ctx - the context in which this conversion is taking place
      obj - the object to convert
      Returns:
      the String value of the object

    • coerceToType

      public static final <T> T coerceToType(ELContext ctx, Object obj, Class<T> 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)