org.apache.bcel.classfile

## Class Utility

- java.lang.Object
- - org.apache.bcel.classfile.Utility

-     public abstract class Utility
      extends Object

  Utility functions that do not really belong to any class in particular.
  Version:
    $Id: Utility.java 1808131 2017-09-12 16:36:55Z britter $

- - ### Constructor Summary

    Constructors
    Constructor and Description
    `Utility()`

  - ### Method Summary

    All Methods Static Methods Concrete Methods
    Modifier and Type | Method and Description
    --- | ---
    `static String` | `accessToString(int access_flags)` Convert bit field of flags into string such as `static final'.
    `static String` | `accessToString(int access_flags, boolean for_class)` Convert bit field of flags into string such as `static final'.
    `static String` | `classOrInterface(int access_flags)`
    `static int` | `clearBit(int flag, int i)`
    `static String` | `codeToString(byte[] code, ConstantPool constant_pool, int index, int length)`
    `static String` | `codeToString(byte[] code, ConstantPool constant_pool, int index, int length, boolean verbose)` Disassemble a byte array of JVM byte codes starting from code line `index' and return the disassembled string representation.
    `static String` | `codeToString(ByteSequence bytes, ConstantPool constant_pool)`
    `static String` | `codeToString(ByteSequence bytes, ConstantPool constant_pool, boolean verbose)` Disassemble a stream of byte codes and return the string representation.
    `static String` | `compactClassName(String str)` Shorten long class names, java/lang/String becomes String.
    `static String` | `compactClassName(String str, boolean chopit)` Shorten long class names, java/lang/String becomes java.lang.String, e.g..
    `static String` | `compactClassName(String str, String prefix, boolean chopit)` Shorten long class name str, i.e., chop off the prefix, if the class name starts with this string and the flag chopit is true.
    `static String` | `convertString(String label)` Escape all occurences of newline chars '\n', quotes \", etc.
    `static byte[]` | `decode(String s, boolean uncompress)` Decode a string back to a byte array.
    `static String` | `encode(byte[] bytes, boolean compress)` Encode byte array it into Java identifier string, i.e., a string that only contains the following characters: (a, ...
    `static String` | `fillup(String str, int length, boolean left_justify, char fill)` Fillup char with up to length characters with char `fill' and justify it left or right.
    `static String` | `format(int i, int length, boolean left_justify, char fill)` Return a string for an integer justified left or right and filled up with `fill' characters if necessary.
    `static String` | `getSignature(String type)` Parse Java type such as "char", or "java.lang.String[]" and return the signature in byte code format, e.g.
    `static boolean` | `isJavaIdentifierPart(char ch)`
    `static boolean` | `isSet(int flag, int i)`
    `static String[]` | `methodSignatureArgumentTypes(String signature)`
    `static String[]` | `methodSignatureArgumentTypes(String signature, boolean chopit)`
    `static String` | `methodSignatureReturnType(String signature)`
    `static String` | `methodSignatureReturnType(String signature, boolean chopit)`
    `static String` | `methodSignatureToString(String signature, String name, String access)` Converts method signature to string with all class names compacted.
    `static String` | `methodSignatureToString(String signature, String name, String access, boolean chopit)`
    `static String` | `methodSignatureToString(String signature, String name, String access, boolean chopit, LocalVariableTable vars)` A returntype signature represents the return value from a method.
    `static String` | `methodTypeToSignature(String ret, String[] argv)` Converts string containing the method return and argument types to a byte code method signature.
    `static String` | `printArray(Object[] obj)`
    `static String` | `printArray(Object[] obj, boolean braces)`
    `static String` | `printArray(Object[] obj, boolean braces, boolean quote)`
    `static void` | `printArray(PrintStream out, Object[] obj)`
    `static void` | `printArray(PrintWriter out, Object[] obj)`
    `static String` | `replace(String str, String old, String new_)` Replace all occurrences of old in str with new.
    `static short` | `searchOpcode(String name)` Map opcode names to opcode numbers.
    `static int` | `setBit(int flag, int i)`
    `static String` | `signatureToString(String signature)` Converts signature to string with all class names compacted.
    `static String` | `signatureToString(String signature, boolean chopit)` The field signature represents the value of an argument to a function or the value of a variable.
    `static String` | `toHexString(byte[] bytes)` Convert bytes into hexadecimal string
    `static byte` | `typeOfMethodSignature(String signature)` Return type of method signature as a byte value as defined in Constants
    `static byte` | `typeOfSignature(String signature)` Return type of signature as a byte value as defined in Constants

    - ### Methods inherited from class java.lang.Object

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

- - ### Constructor Detail

    - #### Utility

          public Utility()

  - ### Method Detail

    - #### accessToString

          public static String accessToString(int access_flags)

      Convert bit field of flags into string such as `static final'.
      Parameters:
        `access_flags` - Access flags
      Returns:
        String representation of flags

    - #### accessToString

          public static String accessToString(int access_flags,
                                              boolean for_class)

      Convert bit field of flags into string such as `static final'. Special case: Classes compiled with new compilers and with the `ACC_SUPER' flag would be said to be "synchronized". This is because SUN used the same value for the flags `ACC_SUPER' and `ACC_SYNCHRONIZED'.
      Parameters:
        `access_flags` - Access flags
        `for_class` - access flags are for class qualifiers ?
      Returns:
        String representation of flags

    - #### classOrInterface

          public static String classOrInterface(int access_flags)

      Parameters:
        `access_flags` - the class flags
      Returns:
        "class" or "interface", depending on the ACC_INTERFACE flag

    - #### codeToString

          public static String codeToString(byte[] code,
                                            ConstantPool constant_pool,
                                            int index,
                                            int length,
                                            boolean verbose)

      Disassemble a byte array of JVM byte codes starting from code line `index' and return the disassembled string representation. Decode only `num' opcodes (including their operands), use -1 if you want to decompile everything.
      Parameters:
        `code` - byte code array
        `constant_pool` - Array of constants
        `index` - offset in `code' array (number of opcodes, not bytes!)
        `length` - number of opcodes to decompile, -1 for all
        `verbose` - be verbose, e.g. print constant pool index
      Returns:
        String representation of byte codes

    - #### codeToString

          public static String codeToString(byte[] code,
                                            ConstantPool constant_pool,
                                            int index,
                                            int length)

    - #### codeToString

          public static String codeToString(ByteSequence bytes,
                                            ConstantPool constant_pool,
                                            boolean verbose)
                                     throws IOException

      Disassemble a stream of byte codes and return the string representation.
      Parameters:
        `bytes` - stream of bytes
        `constant_pool` - Array of constants
        `verbose` - be verbose, e.g. print constant pool index
      Returns:
        String representation of byte code
      Throws:
        `IOException` - if a failure from reading from the bytes argument occurs

    - #### codeToString

          public static String codeToString(ByteSequence bytes,
                                            ConstantPool constant_pool)
                                     throws IOException

      Throws:
        `IOException`

    - #### compactClassName

          public static String compactClassName(String str)

      Shorten long class names, java/lang/String becomes String.
      Parameters:
        `str` - The long class name
      Returns:
        Compacted class name

    - #### compactClassName

          public static String compactClassName(String str,
                                                String prefix,
                                                boolean chopit)

      Shorten long class name str, i.e., chop off the prefix, if the class name starts with this string and the flag chopit is true. Slashes / are converted to dots ..
      Parameters:
        `str` - The long class name
        `prefix` - The prefix the get rid off
        `chopit` - Flag that determines whether chopping is executed or not
      Returns:
        Compacted class name

    - #### compactClassName

          public static String compactClassName(String str,
                                                boolean chopit)

      Shorten long class names, java/lang/String becomes java.lang.String, e.g.. If chopit is true the prefix java.lang is also removed.
      Parameters:
        `str` - The long class name
        `chopit` - Flag that determines whether chopping is executed or not
      Returns:
        Compacted class name

    - #### setBit

          public static int setBit(int flag,
                                   int i)

      Returns:
        `flag' with bit `i' set to 1

    - #### clearBit

          public static int clearBit(int flag,
                                     int i)

      Returns:
        `flag' with bit `i' set to 0

    - #### isSet

          public static boolean isSet(int flag,
                                      int i)

      Returns:
        true, if bit `i' in `flag' is set

    - #### methodTypeToSignature

          public static String methodTypeToSignature(String ret,
                                                     String[] argv)
                                              throws ClassFormatException

      Converts string containing the method return and argument types to a byte code method signature.
      Parameters:
        `ret` - Return type of method
        `argv` - Types of method arguments
      Returns:
        Byte code representation of method signature
      Throws:
        `ClassFormatException` - if the signature is for Void

    - #### methodSignatureArgumentTypes

          public static String[] methodSignatureArgumentTypes(String signature)
                                                       throws ClassFormatException

      Parameters:
        `signature` - Method signature
      Returns:
        Array of argument types
      Throws:
        `ClassFormatException`

    - #### methodSignatureArgumentTypes

          public static String[] methodSignatureArgumentTypes(String signature,
                                                              boolean chopit)
                                                       throws ClassFormatException

      Parameters:
        `signature` - Method signature
        `chopit` - Shorten class names ?
      Returns:
        Array of argument types
      Throws:
        `ClassFormatException`

    - #### methodSignatureReturnType

          public static String methodSignatureReturnType(String signature)
                                                  throws ClassFormatException

      Parameters:
        `signature` - Method signature
      Returns:
        return type of method
      Throws:
        `ClassFormatException`

    - #### methodSignatureReturnType

          public static String methodSignatureReturnType(String signature,
                                                         boolean chopit)
                                                  throws ClassFormatException

      Parameters:
        `signature` - Method signature
        `chopit` - Shorten class names ?
      Returns:
        return type of method
      Throws:
        `ClassFormatException`

    - #### methodSignatureToString

          public static String methodSignatureToString(String signature,
                                                       String name,
                                                       String access)

      Converts method signature to string with all class names compacted.
      Parameters:
        `signature` - to convert
        `name` - of method
        `access` - flags of method
      Returns:
        Human readable signature

    - #### methodSignatureToString

          public static String methodSignatureToString(String signature,
                                                       String name,
                                                       String access,
                                                       boolean chopit)

    - #### methodSignatureToString

          public static String methodSignatureToString(String signature,
                                                       String name,
                                                       String access,
                                                       boolean chopit,
                                                       LocalVariableTable vars)
                                                throws ClassFormatException

      A returntype signature represents the return value from a method. It is a series of bytes in the following grammar:

           <return_signature> ::= <field_type> | V

      The character V indicates that the method returns no value. Otherwise, the signature indicates the type of the return value. An argument signature represents an argument passed to a method:

           <argument_signature> ::= <field_type>

      A method signature represents the arguments that the method expects, and the value that it returns.

           <method_signature> ::= (<arguments_signature>) <return_signature>
           <arguments_signature>::= <argument_signature>*

      This method converts such a string into a Java type declaration like `void main(String[])' and throws a `ClassFormatException' when the parsed type is invalid.
      Parameters:
        `signature` - Method signature
        `name` - Method name
        `access` - Method access rights
        `chopit` -
        `vars` -
      Returns:
        Java type declaration
      Throws:
        `ClassFormatException`

    - #### replace

          public static String replace(String str,
                                       String old,
                                       String new_)

      Replace all occurrences of old in str with new.
      Parameters:
        `str` - String to permute
        `old` - String to be replaced
        `new_` - Replacement string
      Returns:
        new String object

    - #### signatureToString

          public static String signatureToString(String signature)

      Converts signature to string with all class names compacted.
      Parameters:
        `signature` - to convert
      Returns:
        Human readable signature

    - #### signatureToString

          public static String signatureToString(String signature,
                                                 boolean chopit)

      The field signature represents the value of an argument to a function or the value of a variable. It is a series of bytes generated by the following grammar:

           <field_signature> ::= <field_type>
           <field_type>      ::= <base_type>|<object_type>|<array_type>
           <base_type>       ::= B|C|D|F|I|J|S|Z
           <object_type>     ::= L<fullclassname>;
           <array_type>      ::= [<field_type>

           The meaning of the base types is as follows:
           B byte signed byte
           C char character
           D double double precision IEEE float
           F float single precision IEEE float
           I int integer
           J long long integer
           L<fullclassname>; ... an object of the given class
           S short signed short
           Z boolean true or false
           [<field sig> ... array

      This method converts this string into a Java type declaration such as `String[]' and throws a `ClassFormatException' when the parsed type is invalid.
      Parameters:
        `signature` - Class signature
        `chopit` - Flag that determines whether chopping is executed or not
      Returns:
        Java type declaration
      Throws:
        `ClassFormatException`

    - #### getSignature

          public static String getSignature(String type)

      Parse Java type such as "char", or "java.lang.String[]" and return the signature in byte code format, e.g. "C" or "[Ljava/lang/String;" respectively.
      Parameters:
        `type` - Java type
      Returns:
        byte code signature

    - #### typeOfMethodSignature

          public static byte typeOfMethodSignature(String signature)
                                            throws ClassFormatException

      Return type of method signature as a byte value as defined in Constants
      Parameters:
        `signature` - in format described above
      Returns:
        type of method signature
      Throws:
        `ClassFormatException` - if signature is not a method signature
      See Also:
        `Const`

    - #### typeOfSignature

          public static byte typeOfSignature(String signature)
                                      throws ClassFormatException

      Return type of signature as a byte value as defined in Constants
      Parameters:
        `signature` - in format described above
      Returns:
        type of signature
      Throws:
        `ClassFormatException` - if signature isn't a known type
      See Also:
        `Const`

    - #### searchOpcode

          public static short searchOpcode(String name)

      Map opcode names to opcode numbers. E.g., return Constants.ALOAD for "aload"

    - #### toHexString

          public static String toHexString(byte[] bytes)

      Convert bytes into hexadecimal string
      Parameters:
        `bytes` - an array of bytes to convert to hexadecimal
      Returns:
        bytes as hexadecimal string, e.g. 00 fa 12 ...

    - #### format

          public static String format(int i,
                                      int length,
                                      boolean left_justify,
                                      char fill)

      Return a string for an integer justified left or right and filled up with `fill' characters if necessary.
      Parameters:
        `i` - integer to format
        `length` - length of desired string
        `left_justify` - format left or right
        `fill` - fill character
      Returns:
        formatted int

    - #### fillup

          public static String fillup(String str,
                                      int length,
                                      boolean left_justify,
                                      char fill)

      Fillup char with up to length characters with char `fill' and justify it left or right.
      Parameters:
        `str` - string to format
        `length` - length of desired string
        `left_justify` - format left or right
        `fill` - fill character
      Returns:
        formatted string

    - #### printArray

          public static void printArray(PrintStream out,
                                        Object[] obj)

    - #### printArray

          public static void printArray(PrintWriter out,
                                        Object[] obj)

    - #### printArray

          public static String printArray(Object[] obj)

    - #### printArray

          public static String printArray(Object[] obj,
                                          boolean braces)

    - #### printArray

          public static String printArray(Object[] obj,
                                          boolean braces,
                                          boolean quote)

    - #### isJavaIdentifierPart

          public static boolean isJavaIdentifierPart(char ch)

      Parameters:
        `ch` - the character to test if it's part of an identifier
      Returns:
        true, if character is one of (a, ... z, A, ... Z, 0, ... 9, _)

    - #### encode

          public static String encode(byte[] bytes,
                                      boolean compress)
                               throws IOException

      Encode byte array it into Java identifier string, i.e., a string that only contains the following characters: (a, ... z, A, ... Z, 0, ... 9, _, $). The encoding algorithm itself is not too clever: if the current byte's ASCII value already is a valid Java identifier part, leave it as it is. Otherwise it writes the escape character($) followed by:
      - the ASCII value as a hexadecimal string, if the value is not in the range 200..247
      - a Java identifier char not used in a lowercase hexadecimal string, if the value is in the range 200..247

      This operation inflates the original byte array by roughly 40-50%

      Parameters:
        `bytes` - the byte array to convert
        `compress` - use gzip to minimize string
      Throws:
        `IOException` - if there's a gzip exception

    - #### decode

          public static byte[] decode(String s,
                                      boolean uncompress)
                               throws IOException

      Decode a string back to a byte array.
      Parameters:
        `s` - the string to convert
        `uncompress` - use gzip to uncompress the stream of bytes
      Throws:
        `IOException` - if there's a gzip exception

    - #### convertString

          public static String convertString(String label)

      Escape all occurences of newline chars '\n', quotes \", etc.

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