ELSupport (Apache Tomcat 9.0.37 API Documentation)

org.apache.el.lang

## 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 Summary

    Fields
    Modifier and Type | Field and Description
    --- | ---
    `protected static boolean` | `COERCE_TO_ZERO`

  - ### Constructor Summary

    Constructors
    Constructor and Description
    `ELSupport()`

  - ### Method Summary

    All Methods Static Methods Concrete Methods
    Modifier and Type | Method and Description
    --- | ---
    `static Boolean` | `coerceToBoolean(ELContext ctx, Object obj, boolean primitive)` Convert an object to Boolean.
    `static Enum<?>` | `coerceToEnum(ELContext ctx, Object obj, Class type)`
    `static Number` | `coerceToNumber(ELContext ctx, Object obj, Class<?> type)`
    `protected static Number` | `coerceToNumber(Number number, Class<?> type)`
    `protected static Number` | `coerceToNumber(String val, Class<?> type)`
    `static String` | `coerceToString(ELContext ctx, Object obj)` Coerce an object to a string.
    `static 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 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`

- - ### Field Detail

    - #### COERCE_TO_ZERO

          protected static final boolean COERCE_TO_ZERO

  - ### Constructor Detail

    - #### ELSupport

          public ELSupport()

  - ### Method Detail

    - #### 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 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 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)

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