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org.apache.derby.iapi.services.classfile
Class CONSTANT_Index_info  view CONSTANT_Index_info download CONSTANT_Index_info.java

java.lang.Object
  extended byorg.apache.derby.iapi.services.classfile.ConstantPoolEntry
      extended byorg.apache.derby.iapi.services.classfile.CONSTANT_Index_info

final class CONSTANT_Index_info
extends ConstantPoolEntry

A generic constant pool entry for entries that simply hold indexes into other entries.
Ref Constant Pool Entry - page 94 - Section 4.4.2 - Two indexes
NameAndType Constant Pool Entry - page 99 - Section 4.4.6 - Two indexes
String Constant Pool Entry - page 96 - Section 4.4.3 - One index
Class Reference Constant Pool Entry - page 93 - Section 4.4.1 - One index


Field Summary
private  int i1
           
private  int i2
           
 
Fields inherited from class org.apache.derby.iapi.services.classfile.ConstantPoolEntry
doubleSlot, index, tag
 
Constructor Summary
(package private) CONSTANT_Index_info(int tag, int i1, int i2)
           
 
Method Summary
(package private)  int classFileSize()
          Return an estimate of the size of the constant pool entry.
 boolean equals(java.lang.Object other)
          Determine whether this Object is semantically equal to another Object.
 int getI1()
          Get the first index in a index type pool entry.
 int getI2()
          Get the second index in a index type pool entry.
 int hashCode()
          Get a value that represents this Object, as uniquely as possible within the confines of an int.
(package private)  void put(ClassFormatOutput out)
           
(package private)  void set(int tag, int i1, int i2)
          Used when searching
 
Methods inherited from class org.apache.derby.iapi.services.classfile.ConstantPoolEntry
doubleSlot, getIndex, getKey, getTag, setIndex
 
Methods inherited from class java.lang.Object
clone, finalize, getClass, notify, notifyAll, toString, wait, wait, wait
 

Field Detail

i1

private int i1

i2

private int i2
Constructor Detail

CONSTANT_Index_info

CONSTANT_Index_info(int tag,
                    int i1,
                    int i2)
Method Detail

hashCode

public int hashCode()
Description copied from class: java.lang.Object
Get a value that represents this Object, as uniquely as possible within the confines of an int.

There are some requirements on this method which subclasses must follow:

  • Semantic equality implies identical hashcodes. In other words, if a.equals(b) is true, then a.hashCode() == b.hashCode() must be as well. However, the reverse is not necessarily true, and two objects may have the same hashcode without being equal.
  • It must be consistent. Whichever value o.hashCode() returns on the first invocation must be the value returned on all later invocations as long as the object exists. Notice, however, that the result of hashCode may change between separate executions of a Virtual Machine, because it is not invoked on the same object.

Notice that since hashCode is used in java.util.Hashtable and other hashing classes, a poor implementation will degrade the performance of hashing (so don't blindly implement it as returning a constant!). Also, if calculating the hash is time-consuming, a class may consider caching the results.

The default implementation returns System.identityHashCode(this)


equals

public boolean equals(java.lang.Object other)
Description copied from class: java.lang.Object
Determine whether this Object is semantically equal to another Object.

There are some fairly strict requirements on this method which subclasses must follow:

  • It must be transitive. If a.equals(b) and b.equals(c), then a.equals(c) must be true as well.
  • It must be symmetric. a.equals(b) and b.equals(a) must have the same value.
  • It must be reflexive. a.equals(a) must always be true.
  • It must be consistent. Whichever value a.equals(b) returns on the first invocation must be the value returned on all later invocations.
  • a.equals(null) must be false.
  • It must be consistent with hashCode(). That is, a.equals(b) must imply a.hashCode() == b.hashCode(). The reverse is not true; two objects that are not equal may have the same hashcode, but that has the potential to harm hashing performance.

This is typically overridden to throw a java.lang.ClassCastException if the argument is not comparable to the class performing the comparison, but that is not a requirement. It is legal for a.equals(b) to be true even though a.getClass() != b.getClass(). Also, it is typical to never cause a java.lang.NullPointerException.

In general, the Collections API (java.util) use the equals method rather than the == operator to compare objects. However, java.util.IdentityHashMap is an exception to this rule, for its own good reasons.

The default implementation returns this == o.


set

void set(int tag,
         int i1,
         int i2)
Used when searching


classFileSize

int classFileSize()
Description copied from class: ConstantPoolEntry
Return an estimate of the size of the constant pool entry.

Specified by:
classFileSize in class ConstantPoolEntry

put

void put(ClassFormatOutput out)
   throws java.io.IOException
Overrides:
put in class ConstantPoolEntry

getI1

public int getI1()
Description copied from class: ConstantPoolEntry
Get the first index in a index type pool entry. This call is valid when getTag() returns one of
  • CONSTANT_Class
  • CONSTANT_Fieldref
  • CONSTANT_Methodref
  • CONSTANT_InterfaceMethodref
  • CONSTANT_String
  • CONSTANT_NameAndType

Overrides:
getI1 in class ConstantPoolEntry

getI2

public int getI2()
Description copied from class: ConstantPoolEntry
Get the second index in a index type pool entry. This call is valid when getTag() returns one of
  • CONSTANT_Fieldref
  • CONSTANT_Methodref
  • CONSTANT_InterfaceMethodref
  • CONSTANT_NameAndType

Overrides:
getI2 in class ConstantPoolEntry