Class Utils


  • public final class Utils
    extends java.lang.Object
    General utility methods.
    • Field Summary

      Fields 
      Modifier and Type Field Description
      private static java.lang.String SYSTEM_PROPERTIES_FILE
      The file name of configuration file.
    • Constructor Summary

      Constructors 
      Modifier Constructor Description
      private Utils()
      The private constructor of Utils.
    • Method Summary

      All Methods Static Methods Concrete Methods Deprecated Methods 
      Modifier and Type Method Description
      static void checkArgument​(boolean expression)
      Ensures the truth of an expression involving one or more parameters to the calling method.
      static void checkArgument​(boolean expression, java.lang.Object errorMessage)
      Checks the truth of an expression.
      static <T> T checkNotNull​(T reference)
      Deprecated.
      Use Objects.requireNonNull(Object).
      static void checkState​(boolean expression)
      Ensures the truth of an expression involving the state of the calling instance, but not involving any parameters to the calling method.
      static void checkState​(boolean expression, java.lang.String message)
      Ensures the truth of an expression involving the state of the calling instance, but not involving any parameters to the calling method.
      static CryptoCipher getCipherInstance​(java.lang.String transformation, java.util.Properties properties)
      Helper method to create a CryptoCipher instance and throws only IOException.
      static java.util.Properties getDefaultProperties()
      Gets a properties instance that defaults to the System Properties plus any other properties found in the file SYSTEM_PROPERTIES_FILE
      static java.util.Properties getProperties​(java.util.Properties newProp)
      Gets the properties merged with default properties.
      (package private) static java.lang.String libraryPath​(java.lang.String name)  
      static java.util.List<java.lang.String> splitClassNames​(java.lang.String clazzNames, java.lang.String separator)
      Splits class names sequence into substrings, Trim each substring into an entry,and returns an list of the entries.
      • Methods inherited from class java.lang.Object

        clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait
    • Field Detail

      • SYSTEM_PROPERTIES_FILE

        private static final java.lang.String SYSTEM_PROPERTIES_FILE
        The file name of configuration file.
        See Also:
        Constant Field Values
    • Constructor Detail

      • Utils

        private Utils()
        The private constructor of Utils.
    • Method Detail

      • checkArgument

        public static void checkArgument​(boolean expression)
        Ensures the truth of an expression involving one or more parameters to the calling method.
        Parameters:
        expression - a boolean expression.
        Throws:
        java.lang.IllegalArgumentException - if expression is false.
      • checkArgument

        public static void checkArgument​(boolean expression,
                                         java.lang.Object errorMessage)
        Checks the truth of an expression.
        Parameters:
        expression - a boolean expression.
        errorMessage - the exception message to use if the check fails; will be converted to a string using String .valueOf(Object).
        Throws:
        java.lang.IllegalArgumentException - if expression is false.
      • checkNotNull

        @Deprecated
        public static <T> T checkNotNull​(T reference)
        Deprecated.
        Use Objects.requireNonNull(Object).
        Ensures that an object reference passed as a parameter to the calling method is not null.
        Type Parameters:
        T - the type of the object reference to be checked.
        Parameters:
        reference - an object reference.
        Returns:
        the non-null reference that was validated.
        Throws:
        java.lang.NullPointerException - if reference is null.
      • checkState

        public static void checkState​(boolean expression)
        Ensures the truth of an expression involving the state of the calling instance, but not involving any parameters to the calling method.
        Parameters:
        expression - a boolean expression.
        Throws:
        java.lang.IllegalStateException - if expression is false.
      • checkState

        public static void checkState​(boolean expression,
                                      java.lang.String message)
        Ensures the truth of an expression involving the state of the calling instance, but not involving any parameters to the calling method.
        Parameters:
        expression - a boolean expression.
        message - Error message for the exception when the expression is false.
        Throws:
        java.lang.IllegalStateException - if expression is false.
      • getCipherInstance

        public static CryptoCipher getCipherInstance​(java.lang.String transformation,
                                                     java.util.Properties properties)
                                              throws java.io.IOException
        Helper method to create a CryptoCipher instance and throws only IOException.
        Parameters:
        properties - The Properties class represents a set of properties.
        transformation - the name of the transformation, e.g., AES/CBC/PKCS5Padding. See the Java Cryptography Architecture Standard Algorithm Name Documentation for information about standard transformation names.
        Returns:
        the CryptoCipher instance.
        Throws:
        java.io.IOException - if an I/O error occurs.
      • getDefaultProperties

        public static java.util.Properties getDefaultProperties()
        Gets a properties instance that defaults to the System Properties plus any other properties found in the file SYSTEM_PROPERTIES_FILE
        Returns:
        a Properties instance with defaults
      • getProperties

        public static java.util.Properties getProperties​(java.util.Properties newProp)
        Gets the properties merged with default properties.
        Parameters:
        newProp - User-defined properties
        Returns:
        User-defined properties with the default properties
      • libraryPath

        static java.lang.String libraryPath​(java.lang.String name)
      • splitClassNames

        public static java.util.List<java.lang.String> splitClassNames​(java.lang.String clazzNames,
                                                                       java.lang.String separator)
        Splits class names sequence into substrings, Trim each substring into an entry,and returns an list of the entries.
        Parameters:
        clazzNames - a string consist of a list of the entries joined by a delimiter, may be null or empty in which case an empty list is returned.
        separator - a delimiter for the input string.
        Returns:
        a list of class entries.