HashCode (iText 7 7.0.6 API)

java.lang.Object
- com.itextpdf.io.util.HashCode

public final class HashCode
extends Object

This class is a convenience method to sequentially calculate hash code of the object based on the field values. The result depends on the order of elements appended. The exact formula is the same as for java.util.List.hashCode. If you need order independent hash code just summate, multiply or XOR all elements.

Suppose we have class:


 class Thing {
     long id;
     String name;
     float weight;
 }

The hash code calculation can be expressed in 2 forms.

For maximum performance:


 public int hashCode() {
     int hashCode = HashCode.EMPTY_HASH_CODE;
     hashCode = HashCode.combine(hashCode, id);
     hashCode = HashCode.combine(hashCode, name);
     hashCode = HashCode.combine(hashCode, weight);
     return hashCode;
 }

For convenience:


 public int hashCode() {
     return new HashCode().append(id).append(name).append(weight).hashCode();
 }

See Also:: List.hashCode()

Field Summary

Fields
Modifier and Type	Field and Description
`static int`	`EMPTY_HASH_CODE` The hashCode value before any data is appended, equals to 1.

Constructor Summary

Constructors

Constructor and Description

HashCode()

Constructors
Constructor and Description
`HashCode()`

Method Summary

All Methods Static Methods Instance Methods Concrete Methods
Modifier and Type	Method and Description
`HashCode`	`append(boolean value)` Appends value's hashCode to the current hashCode.
`HashCode`	`append(double value)` Appends value's hashCode to the current hashCode.
`HashCode`	`append(float value)` Appends value's hashCode to the current hashCode.
`HashCode`	`append(int value)` Appends value's hashCode to the current hashCode.
`HashCode`	`append(long value)` Appends value's hashCode to the current hashCode.
`HashCode`	`append(Object value)` Appends value's hashCode to the current hashCode.
`static int`	`combine(int hashCode, boolean value)` Combines hashCode of previous elements sequence and value's hashCode.
`static int`	`combine(int hashCode, double value)` Combines hashCode of previous elements sequence and value's hashCode.
`static int`	`combine(int hashCode, float value)` Combines hashCode of previous elements sequence and value's hashCode.
`static int`	`combine(int hashCode, int value)` Combines hashCode of previous elements sequence and value's hashCode.
`static int`	`combine(int hashCode, long value)` Combines hashCode of previous elements sequence and value's hashCode.
`static int`	`combine(int hashCode, Object value)` Combines hashCode of previous elements sequence and value's hashCode.
`int`	`hashCode()` Returns accumulated hashCode

Methods inherited from class java.lang.Object
clone, equals, finalize, getClass, notify, notifyAll, toString, wait, wait, wait

- Field Detail
  - EMPTY_HASH_CODE
```
public static final int EMPTY_HASH_CODE
```
    The hashCode value before any data is appended, equals to 1.
    
    See Also:
    
    List.hashCode(), Constant Field Values
- Constructor Detail
  - HashCode
```
public HashCode()
```
- Method Detail
  - hashCode
```
public final int hashCode()
```
    Returns accumulated hashCode
    
    Overrides:
    
    hashCode in class Object
  - combine
```
public static int combine(int hashCode,
                          boolean value)
```
    Combines hashCode of previous elements sequence and value's hashCode.
    
    Parameters:
    
    hashCode - previous hashCode value
    
    value - new element
    
    Returns:
    
    combined hashCode
  - combine
```
public static int combine(int hashCode,
                          long value)
```
    Combines hashCode of previous elements sequence and value's hashCode.
    
    Parameters:
    
    hashCode - previous hashCode value
    
    value - new element
    
    Returns:
    
    combined hashCode
  - combine
```
public static int combine(int hashCode,
                          float value)
```
    Combines hashCode of previous elements sequence and value's hashCode.
    
    Parameters:
    
    hashCode - previous hashCode value
    
    value - new element
    
    Returns:
    
    combined hashCode
  - combine
```
public static int combine(int hashCode,
                          double value)
```
    Combines hashCode of previous elements sequence and value's hashCode.
    
    Parameters:
    
    hashCode - previous hashCode value
    
    value - new element
    
    Returns:
    
    combined hashCode
  - combine
```
public static int combine(int hashCode,
                          Object value)
```
    Combines hashCode of previous elements sequence and value's hashCode.
    
    Parameters:
    
    hashCode - previous hashCode value
    
    value - new element
    
    Returns:
    
    combined hashCode
  - combine
```
public static int combine(int hashCode,
                          int value)
```
    Combines hashCode of previous elements sequence and value's hashCode.
    
    Parameters:
    
    hashCode - previous hashCode value
    
    value - new element
    
    Returns:
    
    combined hashCode
  - append
```
public final HashCode append(int value)
```
    Appends value's hashCode to the current hashCode.
    
    Parameters:
    
    value - new element
    
    Returns:
    
    this
  - append
```
public final HashCode append(long value)
```
    Appends value's hashCode to the current hashCode.
    
    Parameters:
    
    value - new element
    
    Returns:
    
    this
  - append
```
public final HashCode append(float value)
```
    Appends value's hashCode to the current hashCode.
    
    Parameters:
    
    value - new element
    
    Returns:
    
    this
  - append
```
public final HashCode append(double value)
```
    Appends value's hashCode to the current hashCode.
    
    Parameters:
    
    value - new element
    
    Returns:
    
    this
  - append
```
public final HashCode append(boolean value)
```
    Appends value's hashCode to the current hashCode.
    
    Parameters:
    
    value - new element
    
    Returns:
    
    this
  - append
```
public final HashCode append(Object value)
```
    Appends value's hashCode to the current hashCode.
    
    Parameters:
    
    value - new element
    
    Returns:
    
    this

Class HashCode

Field Summary

Constructor Summary

Method Summary

Methods inherited from class java.lang.Object

Field Detail

EMPTY_HASH_CODE

Constructor Detail

HashCode

Method Detail

hashCode

combine

combine

combine

combine

combine

combine

append

append

append

append

append

append