ELSupport (Apache Tomcat 9.0.120 API Documentation)
Description: declaration: package: org.apache.el.lang, class: ELSupport

# Class ELSupport

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

public class ELSupport extends Object
A helper class that implements the EL Specification.

- ## Field Summary

  Fields
  Modifier and Type
  Field
  Description
  `protected static final boolean`
  `COERCE_TO_ZERO`

- ## Constructor Summary

  Constructors
  Constructor
  Description
  `ELSupport()`

- ## Method Summary

  Modifier and Type
  Method
  Description
  `static Boolean`
  `coerceToBoolean(ELContext ctx, Object obj, boolean primitive)`
  Convert an object to Boolean.
  `static Enum<?>`
  `coerceToEnum(ELContext ctx, Object obj, Class type)`
  Coerces an object to an Enum value of the specified type.
  `protected static Number`
  `coerceToNumber(Number number, Class<?> type)`
  Coerces a Number to the specified numeric type.
  `protected static Number`
  `coerceToNumber(String val, Class<?> type)`
  Coerces a String to a Number of the specified type.
  `static Number`
  `coerceToNumber(ELContext ctx, Object obj, Class<?> type)`
  Coerces an object to a Number of the specified type.
  `static String`
  `coerceToString(ELContext ctx, Object obj)`
  Coerce an object to a string.
  `static final Object`
  `coerceToType(ELContext ctx, Object obj, Class<?> type)`
  `static int`
  `compare(ELContext ctx, Object obj0, Object obj1)`
  Compare two objects, after coercing to the same type if appropriate.
  `static boolean`
  `equals(ELContext ctx, Object obj0, Object obj1)`
  Compare two objects for equality, after coercing to the same type if appropriate.
  `static final boolean`
  `isBigDecimalOp(Object obj0, Object obj1)`
  `static boolean`
  `isBigIntegerOp(Object obj0, Object obj1)`
  Checks if either operand is a BigInteger.
  `static boolean`
  `isDoubleOp(Object obj0, Object obj1)`
  Checks if either operand is a Double or Float.
  `static boolean`
  `isLongOp(Object obj0, Object obj1)`
  Checks if either operand is a Long, Integer, Character, Short, or Byte.
  `static boolean`
  `isStringFloat(String str)`
  Checks if a string represents a floating-point number by looking for 'E', 'e', or '.' characters.

  ### Methods inherited from class Object

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

- ## Field Details

  - ### COERCE_TO_ZERO

    protected static final boolean COERCE_TO_ZERO

- ## Constructor Details

  - ### ELSupport

    public ELSupport()

- ## Method Details

  - ### compare

    public static 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 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 Enum<?> coerceToEnum(ELContext ctx, Object obj, Class type)
    Coerces an object to an Enum value of the specified type.

    If the object is null or an empty string, null is returned. If the object is already an instance of the target enum type, it is returned directly. Otherwise, the object must be a String matching one of the enum constant names.

    Parameters:
      `ctx` - the EL context
      `obj` - the object to coerce
      `type` - the target enum type
    Returns:
      the coerced enum value, or null if the object is null or empty
    Throws:
      `ELException` - if the object cannot be coerced to the target enum type

  - ### coerceToBoolean

    public static 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 Number coerceToNumber(Number number, Class<?> type) throws ELException
    Coerces a Number to the specified numeric type.
    Parameters:
      `number` - the number to coerce
      `type` - the target numeric type
    Returns:
      the coerced number
    Throws:
      `ELException` - if the number cannot be coerced to the target type

  - ### coerceToNumber

    public static Number coerceToNumber(ELContext ctx, Object obj, Class<?> type) throws ELException
    Coerces an object to a Number of the specified type.

    Supports coercion from String, Number, and Character types. If the object is null and the target type is not primitive, null is returned (unless COERCE_TO_ZERO is set).

    Parameters:
      `ctx` - the EL context
      `obj` - the object to coerce
      `type` - the target numeric type
    Returns:
      the coerced number, or null if the object is null and the target is not primitive
    Throws:
      `ELException` - if the object cannot be coerced to the target type

  - ### coerceToNumber

    protected static Number coerceToNumber(String val, Class<?> type) throws ELException
    Coerces a String to a Number of the specified type.
    Parameters:
      `val` - the string value to parse
      `type` - the target numeric type
    Returns:
      the coerced number
    Throws:
      `ELException` - if the string cannot be parsed as the target type

  - ### coerceToString

    public static 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 Object coerceToType(ELContext ctx, Object obj, Class<?> type) throws ELException
    Throws:
      `ELException`

  - ### isBigDecimalOp

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

  - ### isBigIntegerOp

    public static boolean isBigIntegerOp(Object obj0, Object obj1)
    Checks if either operand is a BigInteger.
    Parameters:
      `obj0` - the first operand
      `obj1` - the second operand
    Returns:
      true if either operand is a BigInteger

  - ### isDoubleOp

    public static boolean isDoubleOp(Object obj0, Object obj1)
    Checks if either operand is a Double or Float.
    Parameters:
      `obj0` - the first operand
      `obj1` - the second operand
    Returns:
      true if either operand is a Double or Float

  - ### isLongOp

    public static boolean isLongOp(Object obj0, Object obj1)
    Checks if either operand is a Long, Integer, Character, Short, or Byte.
    Parameters:
      `obj0` - the first operand
      `obj1` - the second operand
    Returns:
      true if either operand is a Long-compatible type

  - ### isStringFloat

    public static boolean isStringFloat(String str)
    Checks if a string represents a floating-point number by looking for 'E', 'e', or '.' characters.
    Parameters:
      `str` - the string to check
    Returns:
      true if the string contains floating-point notation