public final class HashCode extends Object
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();
}
List.hashCode()
Modifier and Type | Field and Description |
---|---|
static int |
EMPTY_HASH_CODE
The hashCode value before any data is appended, equals to 1.
|
Constructor and Description |
---|
HashCode() |
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
|
public static final int EMPTY_HASH_CODE
List.hashCode()
, Constant Field Values
public final int hashCode()
public static int combine(int hashCode, boolean value)
hashCode
- previous hashCode value
value
- new element
public static int combine(int hashCode, long value)
hashCode
- previous hashCode value
value
- new element
public static int combine(int hashCode, float value)
hashCode
- previous hashCode value
value
- new element
public static int combine(int hashCode, double value)
hashCode
- previous hashCode value
value
- new element
public static int combine(int hashCode, Object value)
hashCode
- previous hashCode value
value
- new element
public static int combine(int hashCode, int value)
hashCode
- previous hashCode value
value
- new element
public final HashCode append(int value)
value
- new element
public final HashCode append(long value)
value
- new element
public final HashCode append(float value)
value
- new element
public final HashCode append(double value)
value
- new element
public final HashCode append(boolean value)
value
- new element
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