Package ej.bon

Class Constants

  • public class Constants
extends Object
    This class provides access to compile-time constants. A constant is retrieved from its name, and is replaced by its value using the desired getXXX method depending on the expected type.

    The constant name must be resolved by the compiler as a String literal at the location where the getXXX method is called. Constant Expressions are specified in section 15.28 Constant Expressions of the Java Language Specification.

    The following usages are allowed: 

     // Name is a String Literal
 boolean value = Constants.getBoolean("MyConstant")
 
     // Name is a Field Access to a static final field declaration
 // of type String, and initialized with a Constant Expression
 static final String MY_CONSTANT = "My" + "Constant";
 boolean value = Constants.getBoolean(MY_CONSTANT)
    The following usages are not allowed: 
     // Name is a String Object
 boolean value = Constants.getBoolean(new String("MyConstant"))
 
     // Name is a Field Access to a static final field declaration
 // of type String, but not initialized with a Constant Expression
 static final String MY_CONSTANT = getMyConstantName();
 boolean value = Constants.getBoolean(MY_CONSTANT)

    • Constructor Detail

      • Constants

        public Constants()

    • Method Detail

      • getBoolean

        public static boolean getBoolean​(String name)
        Gets a boolean constant.

        The constant is resolved to true if its value is equals to "true", false if its value is equals to "false".

        Parameters:
        name - the constant name
        Returns:
        the boolean constant

      • getByte

        public static byte getByte​(String name)
        Gets a byte constant.

        The constant is resolved to a byte if its value is resolved to an int included into the range [-128,127].

        Parameters:
        name - the constant name
        Returns:
        the byte constant
        See Also:
        getInt(String)

      • getChar

        public static char getChar​(String name)
        Gets a char constant.

        The constant is resolved to a char if its value is resolved to an int included into the range [0,65535].

        Parameters:
        name - the constant name
        Returns:
        the char constant
        See Also:
        getInt(String)

      • getShort

        public static short getShort​(String name)
        Gets a short constant.

        The constant is resolved to a short if its value is resolved to an int included into the range [-32768,32767].

        Parameters:
        name - the constant name
        Returns:
        the short constant
        See Also:
        getInt(String)

      • getInt

        public static int getInt​(String name)
        Gets an int constant.

        The constant is resolved to an int if its String value:

        • is a valid argument for Integer.decode(String)
        • is an unsigned integer written in hexadecimal format such as 0xFFFFFFFF. In this latter case, the constant is resolved to -1.
        Parameters:
        name - the constant name
        Returns:
        the int constant

      • getLong

        public static long getLong​(String name)
        Gets a long constant.

        The constant is resolved to a long if its String value:

        • is a valid argument for Long.decode(String)
        • if an unsigned long written in hexadecimal format such as 0xFFFFFFFFFFFFFFFF. In this latter case, the constant is resolved to -1.
        Parameters:
        name - the constant name
        Returns:
        the long constant

      • getFloat

        public static float getFloat​(String name)
        Gets a float constant.

        The constant is resolved to a float if its value can be loaded by Float.valueOf(String).

        Parameters:
        name - the constant name
        Returns:
        the float constant

      • getDouble

        public static double getDouble​(String name)
        Gets a double constant.

        The constant is resolved to a double if its value can be loaded by Double.valueOf(String).

        Parameters:
        name - the constant name
        Returns:
        the short constant

      • getString

        public static String getString​(String name)
        Gets a String constant.
        Parameters:
        name - the constant name
        Returns:
        the String constant

      • getClass

        public static Class<?> getClass​(String name)
        Gets a Class constant.

        The constant is resolved to a Class if its value describes the fully qualified name of a Class that can be loaded from the classpath.

        Parameters:
        name - the constant name
        Returns:
        the Class constant