com.myjavatools.lib.foundation
Class Objects

java.lang.Object
  com.myjavatools.lib.foundation.Objects

public abstract class Objects
extends java.lang.Object

Objects is a utility class that contains various unsorted static methods for foundation package

Since:

5.0

Version:

5.0, 11/25/04

See Also:

Maps, Function

Constructor Summary

Objects()

Method Summary

static <T> int	indexOf(T what, java.util.List<T> list, int fromIndex) Gets the index of the next element of a list that equals to specified object
static <T> int	indexOf(T what, T[] array) Gets the index of the first element of an array that equals to specified object
static <T> int	indexOf(T what, T[] array, int fromIndex) Gets the index of the next element of an array that equals to specified object
static <T> boolean	isEmpty(T data) In a "creative", anti-scientific way checks whether a string or a container is empty.
static <T> T	oneOf(T... arglist) Chooses the first non-empty object out of objects in parameter list.
static <T> java.util.Set<T>	toSet(T... elements) Deprecated. since 5.0; the usefulness of this method is doubtful
static <T> java.util.Set<T>	union(java.util.Collection<T> first, java.util.Collection<T> second) Deprecated. since 5.0; can do it using ordinary Set.addAll()

Methods inherited from class java.lang.Object

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

Constructor Detail

Objects

public Objects()

Method Detail

indexOf

public static <T> int indexOf(T what,
                              T[] array)

Gets the index of the first element of an array that equals to specified object

Parameters:

what - T the object to look for in array

array - T[] array of objects to look for what

Returns:

index of the object in array, or -1 if none found

Examples:

indexOf("abc", new String[] {"123", "abc", "xyz"}) returns 1;

indexOf(null, new String[] {"123", "abc", null}) returns 2;

indexOf

public static <T> int indexOf(T what,
                              T[] array,
                              int fromIndex)

Gets the index of the next element of an array that equals to specified object

Parameters:

what - T the object to look for in array

array - T[] array of objects to look for what

fromIndex - int start search from this position

Returns:

index of the object in array, or -1 if none found

Examples:

indexOf("abc", new String[] {"abc", "abc", "xyz", 1}) returns 1;

indexOf(null, new String[] {"123", "abc", null}}, 1) returns 2;

indexOf

public static <T> int indexOf(T what,
                              java.util.List<T> list,
                              int fromIndex)

Gets the index of the next element of a list that equals to specified object

Parameters:

what - T the object to look for in list

list - List<T> list of objects to look for what

fromIndex - int start search from this position

Returns:

index of the object in list, or -1 if none found

Examples:

List l = new ArrayList(); l.add("abc"); l.add("abc"), l.add("xyz"); indexOf("abc", list, 1} returns 1;

List l = new ArrayList(); l.add("abc"); l.add("abc"), l.add(null); indexOf(null, list, 1} returns 2;

toSet

public static <T> java.util.Set<T> toSet(T... elements)

Deprecated. since 5.0; the usefulness of this method is doubtful

makes a Set from an array of elements

Parameters:

elements - T[] elements to fill the set

Returns:

Set the set that contains all the elements from array if the array is null, returns null

Examples:

toSet(new String[] {"1", "2", "3").size() return 3;

toSet(3, 1, 4, 1, 5, 9, 2, 6, 5).size() returns 7.

isEmpty

public static final <T> boolean isEmpty(T data)

In a "creative", anti-scientific way checks whether a string or a container is empty.
Accepts a Collection, a Map, an array, a String.

Parameters:

data - a Collection or a Map or an array or a string to check

Returns:

true if data is empty

Examples:

isEmpty(""), isEmpty(null), isEmpty(new HashMap()) all return true;

isEmpty(" "), isEmpty(new int[] {0}) returns false.

oneOf

public static <T> T oneOf(T... arglist)

Chooses the first non-empty object out of objects in parameter list.

Parameters:

arglist - the first candidate ...

Returns:

the first one of the list of candidates that is not empty, converted to String

Examples:

oneOf(null, "xyz") returns "xyz";

oneOf("abc", "xyz") returns "abc";

oneOf(null, "", "xyz") returns "xyz";

oneOf("abc", null, "xyz") returns "abc";

oneOf("", "def", null) returns "def";

oneOf(null, null, 2) returns 2.

oneOf("abc", null, "pqr", "xyz") returns "abc";

oneOf("", "def", null, "xyz") returns "def";

union

public static <T> java.util.Set<T> union(java.util.Collection<T> first,
                                         java.util.Collection<T> second)

Deprecated. since 5.0; can do it using ordinary Set.addAll()

Creates set union of two collections

Parameters:

first - Collection

second - Collection

Returns:

Set that is a union of first and second as sets. nulls are tolerated and ignored

Example:

union(Arrays.asList(new String[] {"a", "b", "c"}), Arrays.asList(new String[] {"b", "a", "d"}) returns the same list as new HashSet(Arrays.asList(new String[] {"a", "b", "c", "d"})).