Package com.ontology2.pidove.util

Class Null

java.lang.Object

com.ontology2.pidove.util.Null

public class Null
extends Object

Functions for handling nulls

Constructor Summary

Constructors

Constructor	Description
Null()

Method Summary

Modifier and Type	Method	Description
static <X> X	coalesce(X a, X b)	Null coalescing operator returns the first argument that isn't null or null if all arguments are null.
static <X> X	coalesce(X a, X b, X c)
static <X> X	coalesce(X a, X b, X c, X... d)	Null coalescing operator Since all the values are the same type this can be implemented for an arbitrary number of values with varargs
static <X, Y> Y	safe(X x, Function<X,Y> f1)	Safe navigation operator.
static <X, Y, Z> Z	safe(X x, Function<X,Y> f1, Function<Y,Z> f2)
static <X, Y, Z, ZZ> ZZ	safe(X x, Function<X,Y> f1, Function<Y,Z> f2, Function<Z,ZZ> f3)
static <X> void	safe0(X x, Consumer<X> f1)	Safe navigation operator.
static <X, Y> void	safe0(X x, Function<X,Y> f1, Consumer<Y> c)
static <X, Y, Z> void	safe0(X x, Function<X,Y> f1, Function<Y,Z> f2, Consumer<Z> f3)

Methods inherited from class java.lang.Object

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

Constructor Details

Null

public Null()

Method Details

coalesce

public static <X> X coalesce(X a,
 X b)

Null coalescing operator returns the first argument that isn't null or null if all arguments are null.

Type Parameters:

X - the return data type

Parameters:

a - a value of type a

b - a value of type b

Returns:

a if a is not null otherwise b

coalesce

public static <X> X coalesce(X a,
 X b,
 X c)

coalesce

@SafeVarargs
public static <X> X coalesce(X a,
 X b,
 X c,
 X... d)

Null coalescing operator Since all the values are the same type this can be implemented for an arbitrary number of values with varargs

Type Parameters:

X - the returned data type

Parameters:

a - first value

b - second value

c - third value

d - more arguments...

Returns:

the first non-null value.

safe

public static <X,
Y> Y safe(X x,
 Function<X,Y> f1)

Safe navigation operator. If x is null returns null, otherwise applies f1 to x. Longer variants apply any functions that occur in later arguments, doing the null check each time.

Type Parameters:

X - input type

Y - output type

Parameters:

x - input value

f1 - function that can be applied to x

Returns:

null if x is null, otherwise f(x).

safe0

public static <X> void safe0(X x,
 Consumer<X> f1)

Safe navigation operator. If x is null does nothing. If x is not null, makes f1 accept x. Longer variants apply functions in series if the result is not null, finally making the Consumer passed as the last argument accepting that result if it is not null

Type Parameters:

X - input type

Parameters:

x - input value

f1 - consumer that can accept x

safe

public static <X,
Y,
Z> Z safe(X x,
 Function<X,Y> f1,
 Function<Y,Z> f2)

safe0

public static <X,
Y> void safe0(X x,
 Function<X,Y> f1,
 Consumer<Y> c)

safe

public static <X,
Y,
Z,
ZZ> ZZ safe(X x,
 Function<X,Y> f1,
 Function<Y,Z> f2,
 Function<Z,ZZ> f3)

safe0

public static <X,
Y,
Z> void safe0(X x,
 Function<X,Y> f1,
 Function<Y,Z> f2,
 Consumer<Z> f3)