Type (Javassist API)

java.lang.Object
- javassist.bytecode.analysis.Type

Direct Known Subclasses:

MultiArrayType, MultiType
```
public class Type
extends java.lang.Object
```
Represents a JVM type in data-flow analysis. This abstraction is necessary since a JVM type not only includes all normal Java types, but also a few special types that are used by the JVM internally. See the static field types on this class for more info on these special types. All primitive and special types reuse the same instance, so identity comparison can be used when examining them. Normal java types must use equals(Object) to compare type instances. In most cases, applications which consume this API, only need to call getCtClass() to obtain the needed type information.

Author:

Jason T. Greene

Field Summary

Fields
Modifier and Type	Field and Description
`static Type`	`BOGUS` Represents a non-accessible value.
`static Type`	`BOOLEAN` Represents the boolean primitive type
`static Type`	`BYTE` Represents the byte primitive type
`static Type`	`CHAR` Represents the char primitive type
`static Type`	`CLONEABLE` Represents the java.lang.Coneable reference type
`static Type`	`DOUBLE` Represents the double primitive type
`static Type`	`FLOAT` Represents the float primitive type
`static Type`	`INTEGER` Represents the integer primitive type
`static Type`	`LONG` Represents the long primitive type
`static Type`	`OBJECT` Represents the java.lang.Object reference type
`static Type`	`RETURN_ADDRESS` Represents an internal JVM return address, which is used by the RET instruction to return to a JSR that invoked the subroutine.
`static Type`	`SERIALIZABLE` Represents the java.io.Serializable reference type
`static Type`	`SHORT` Represents the short primitive type
`static Type`	`THROWABLE` Represents the java.lang.Throwable reference type
`static Type`	`TOP` A placeholder used by the analyzer for the second word position of a double-word type
`static Type`	`UNINIT` Represents an unknown, or null type.
`static Type`	`VOID` Represents the void primitive type

Method Summary

All Methods Static Methods Instance Methods Concrete Methods
Modifier and Type	Method and Description
`boolean`	`equals(java.lang.Object o)`
`static Type`	`get(CtClass clazz)` Obtain the Type for a given class.
`Type`	`getComponent()` Returns the array component if this type is an array.
`CtClass`	`getCtClass()` Returns the class this type represents.
`int`	`getDimensions()` Returns the number of dimensions of this array.
`int`	`getSize()` Gets the word size of this type.
`boolean`	`isArray()` Returns whether or not this type is an array.
`boolean`	`isAssignableFrom(Type type)` Determines whether this type is assignable, to the passed type.
`boolean`	`isReference()` Returns whether or not this type is a normal java reference, i.e.
`boolean`	`isSpecial()` Returns whether or not the type is special.
`Type`	`merge(Type type)` Finds the common base type, or interface which both this and the specified type can be assigned.
`java.lang.String`	`toString()`

Methods inherited from class java.lang.Object
getClass, hashCode, notify, notifyAll, wait, wait, wait

- Field Detail
  - DOUBLE
```
public static final Type DOUBLE
```
    Represents the double primitive type
  - BOOLEAN
```
public static final Type BOOLEAN
```
    Represents the boolean primitive type
  - LONG
```
public static final Type LONG
```
    Represents the long primitive type
  - CHAR
```
public static final Type CHAR
```
    Represents the char primitive type
  - BYTE
```
public static final Type BYTE
```
    Represents the byte primitive type
  - SHORT
```
public static final Type SHORT
```
    Represents the short primitive type
  - INTEGER
```
public static final Type INTEGER
```
    Represents the integer primitive type
  - FLOAT
```
public static final Type FLOAT
```
    Represents the float primitive type
  - VOID
```
public static final Type VOID
```
    Represents the void primitive type
  - UNINIT
```
public static final Type UNINIT
```
    Represents an unknown, or null type. This occurs when aconst_null is used. It is important not to treat this type as java.lang.Object, since a null can be assigned to any reference type. The analyzer will replace these with an actual known type if it can be determined by a merged path with known type information. If this type is encountered on a frame then it is guaranteed to be null, and the type information is simply not available. Any attempts to infer the type, without further information from the compiler would be a guess.
  - RETURN_ADDRESS
```
public static final Type RETURN_ADDRESS
```
    Represents an internal JVM return address, which is used by the RET instruction to return to a JSR that invoked the subroutine.
  - TOP
```
public static final Type TOP
```
    A placeholder used by the analyzer for the second word position of a double-word type
  - BOGUS
```
public static final Type BOGUS
```
    Represents a non-accessible value. Code cannot access the value this type represents. It occurs when bytecode reuses a local variable table position with non-mergable types. An example would be compiled code which uses the same position for a primitive type in one branch, and a reference type in another branch.
  - OBJECT
```
public static final Type OBJECT
```
    Represents the java.lang.Object reference type
  - SERIALIZABLE
```
public static final Type SERIALIZABLE
```
    Represents the java.io.Serializable reference type
  - CLONEABLE
```
public static final Type CLONEABLE
```
    Represents the java.lang.Coneable reference type
  - THROWABLE
```
public static final Type THROWABLE
```
    Represents the java.lang.Throwable reference type
- Method Detail
  - get
```
public static Type get(CtClass clazz)
```
    Obtain the Type for a given class. If the class is a primitive, the the unique type instance for the primitive will be returned. Otherwise a new Type instance representing the class is returned.
    
    Parameters:
    
    clazz - The java class
    
    Returns:
    
    a type instance for this class
  - getSize
```
public int getSize()
```
    Gets the word size of this type. Double-word types, such as long and double will occupy two positions on the local variable table or stack.
    
    Returns:
    
    the number of words needed to hold this type
  - getCtClass
```
public CtClass getCtClass()
```
    Returns the class this type represents. If the type is special, null will be returned.
    
    Returns:
    
    the class for this type, or null if special
  - isReference
```
public boolean isReference()
```
    Returns whether or not this type is a normal java reference, i.e. it is or extends java.lang.Object.
    
    Returns:
    
    true if a java reference, false if a primitive or special
  - isSpecial
```
public boolean isSpecial()
```
    Returns whether or not the type is special. A special type is one that is either used for internal tracking, or is only used internally by the JVM.
    
    Returns:
    
    true if special, false if not
  - isArray
```
public boolean isArray()
```
    Returns whether or not this type is an array.
    
    Returns:
    
    true if an array, false if not
  - getDimensions
```
public int getDimensions()
```
    Returns the number of dimensions of this array. If the type is not an array zero is returned.
    
    Returns:
    
    zero if not an array, otherwise the number of array dimensions.
  - getComponent
```
public Type getComponent()
```
    Returns the array component if this type is an array. If the type is not an array null is returned.
    
    Returns:
    
    the array component if an array, otherwise null
  - isAssignableFrom
```
public boolean isAssignableFrom(Type type)
```
    Determines whether this type is assignable, to the passed type. A type is assignable to another if it is either the same type, or a sub-type.
    
    Parameters:
    
    type - the type to test assignability to
    
    Returns:
    
    true if this is assignable to type, otherwise false
  - merge
```
public Type merge(Type type)
```
    Finds the common base type, or interface which both this and the specified type can be assigned. If there is more than one possible answer, then a MultiType, or a MultiArrayType is returned. Multi-types have special rules, and successive merges and assignment tests on them will alter their internal state, as well as other multi-types they have been merged with. This method is used by the data-flow analyzer to merge the type state from multiple branches.
    
    Parameters:
    
    type - the type to merge with
    
    Returns:
    
    the merged type
  - equals
```
public boolean equals(java.lang.Object o)
```
    Overrides:
    
    equals in class java.lang.Object
  - toString
```
public java.lang.String toString()
```
    Overrides:
    
    toString in class java.lang.Object

Class Type

Field Summary

Method Summary

Methods inherited from class java.lang.Object

Field Detail

DOUBLE

BOOLEAN

LONG

CHAR

BYTE

SHORT

INTEGER

FLOAT

VOID

UNINIT

RETURN_ADDRESS

TOP

BOGUS

OBJECT

SERIALIZABLE

CLONEABLE

THROWABLE

Method Detail

get

getSize

getCtClass

isReference

isSpecial

isArray

getDimensions

getComponent

isAssignableFrom

merge

equals

toString