Iterables (abacus-common-se-jdk7 2.2.21 API)

java.lang.Object
- com.landawn.abacus.util.Iterables

```
public final class Iterables
extends Object
```
Note: This class includes codes copied from Apache Commons Lang, Google Guava and other open source projects under the Apache License 2.0. The methods copied from other libraries/frameworks/projects may be modified in this class.

This is a utility class for iterable data structures, including Collection/Array/Iterator.

The methods in this class should only read the input Collection/Array/Iterator parameters, not modify them.

See Also:

N, Iterators, Maps, StringUtil

Method Summary

All Methods Static Methods Concrete Methods
Modifier and Type	Method and Description
`static <T extends Number> u.OptionalDouble`	`averageDouble(Collection<? extends T> c)` Returns `OptionalDouble.empty()` if the specified `Array/Collection` is `null` or empty, or `fromIndex == toIndex`.
`static <T extends Number> u.OptionalDouble`	`averageDouble(Collection<? extends T> c, int fromIndex, int toIndex)` Returns `OptionalDouble.empty()` if the specified `Array/Collection` is `null` or empty, or `fromIndex == toIndex`.
`static <T,E extends Exception> u.OptionalDouble`	`averageDouble(Collection<? extends T> c, int fromIndex, int toIndex, Throwables.ToDoubleFunction<? super T,E> func)` Returns `OptionalDouble.empty()` if the specified `Array/Collection` is `null` or empty, or `fromIndex == toIndex`.
`static <T,E extends Exception> u.OptionalDouble`	`averageDouble(Collection<? extends T> c, Throwables.ToDoubleFunction<? super T,E> func)` Returns `OptionalDouble.empty()` if the specified `Array/Collection` is `null` or empty, or `fromIndex == toIndex`.
`static <T extends Number> u.OptionalDouble`	`averageDouble(T[] a)` Returns `OptionalDouble.empty()` if the specified `Array/Collection` is `null` or empty, or `fromIndex == toIndex`.
`static <T extends Number> u.OptionalDouble`	`averageDouble(T[] a, int fromIndex, int toIndex)` Returns `OptionalDouble.empty()` if the specified `Array/Collection` is `null` or empty, or `fromIndex == toIndex`.
`static <T,E extends Exception> u.OptionalDouble`	`averageDouble(T[] a, int fromIndex, int toIndex, Throwables.ToDoubleFunction<? super T,E> func)` Returns `OptionalDouble.empty()` if the specified `Array/Collection` is `null` or empty, or `fromIndex == toIndex`.
`static <T,E extends Exception> u.OptionalDouble`	`averageDouble(T[] a, Throwables.ToDoubleFunction<? super T,E> func)` Returns `OptionalDouble.empty()` if the specified `Array/Collection` is `null` or empty, or `fromIndex == toIndex`.
`static <T extends Number> u.OptionalDouble`	`averageInt(Collection<? extends T> c)` Returns `OptionalDouble.empty()` if the specified `Array/Collection` is `null` or empty, or `fromIndex == toIndex`.
`static <T extends Number> u.OptionalDouble`	`averageInt(Collection<? extends T> c, int fromIndex, int toIndex)` Returns `OptionalDouble.empty()` if the specified `Array/Collection` is `null` or empty, or `fromIndex == toIndex`.
`static <T,E extends Exception> u.OptionalDouble`	`averageInt(Collection<? extends T> c, int fromIndex, int toIndex, Throwables.ToIntFunction<? super T,E> func)` Returns `OptionalDouble.empty()` if the specified `Array/Collection` is `null` or empty, or `fromIndex == toIndex`.
`static <T,E extends Exception> u.OptionalDouble`	`averageInt(Collection<? extends T> c, Throwables.ToIntFunction<? super T,E> func)` Returns `OptionalDouble.empty()` if the specified `Array/Collection` is `null` or empty, or `fromIndex == toIndex`.
`static <T extends Number> u.OptionalDouble`	`averageInt(T[] a)` Returns `OptionalDouble.empty()` if the specified `Array/Collection` is `null` or empty, or `fromIndex == toIndex`.
`static <T extends Number> u.OptionalDouble`	`averageInt(T[] a, int fromIndex, int toIndex)` Returns `OptionalDouble.empty()` if the specified `Array/Collection` is `null` or empty, or `fromIndex == toIndex`.
`static <T,E extends Exception> u.OptionalDouble`	`averageInt(T[] a, int fromIndex, int toIndex, Throwables.ToIntFunction<? super T,E> func)` Returns `OptionalDouble.empty()` if the specified `Array/Collection` is `null` or empty, or `fromIndex == toIndex`.
`static <T,E extends Exception> u.OptionalDouble`	`averageInt(T[] a, Throwables.ToIntFunction<? super T,E> func)` Returns `OptionalDouble.empty()` if the specified `Array/Collection` is `null` or empty, or `fromIndex == toIndex`.
`static <T extends Number> u.OptionalDouble`	`averageLong(Collection<? extends T> c)` Returns `OptionalDouble.empty()` if the specified `Array/Collection` is `null` or empty, or `fromIndex == toIndex`.
`static <T extends Number> u.OptionalDouble`	`averageLong(Collection<? extends T> c, int fromIndex, int toIndex)` Returns `OptionalDouble.empty()` if the specified `Array/Collection` is `null` or empty, or `fromIndex == toIndex`.
`static <T,E extends Exception> u.OptionalDouble`	`averageLong(Collection<? extends T> c, int fromIndex, int toIndex, Throwables.ToLongFunction<? super T,E> func)` Returns `OptionalDouble.empty()` if the specified `Array/Collection` is `null` or empty, or `fromIndex == toIndex`.
`static <T,E extends Exception> u.OptionalDouble`	`averageLong(Collection<? extends T> c, Throwables.ToLongFunction<? super T,E> func)` Returns `OptionalDouble.empty()` if the specified `Array/Collection` is `null` or empty, or `fromIndex == toIndex`.
`static <T extends Number> u.OptionalDouble`	`averageLong(T[] a)` Returns `OptionalDouble.empty()` if the specified `Array/Collection` is `null` or empty, or `fromIndex == toIndex`.
`static <T extends Number> u.OptionalDouble`	`averageLong(T[] a, int fromIndex, int toIndex)` Returns `OptionalDouble.empty()` if the specified `Array/Collection` is `null` or empty, or `fromIndex == toIndex`.
`static <T,E extends Exception> u.OptionalDouble`	`averageLong(T[] a, int fromIndex, int toIndex, Throwables.ToLongFunction<? super T,E> func)` Returns `OptionalDouble.empty()` if the specified `Array/Collection` is `null` or empty, or `fromIndex == toIndex`.
`static <T,E extends Exception> u.OptionalDouble`	`averageLong(T[] a, Throwables.ToLongFunction<? super T,E> func)` Returns `OptionalDouble.empty()` if the specified `Array/Collection` is `null` or empty, or `fromIndex == toIndex`.
`static u.OptionalInt`	`indexOf(Collection<?> c, Object objToFind)`
`static u.OptionalInt`	`indexOf(Object[] a, Object objToFind)`
`static <T extends Comparable<? super T>> u.Nullable<T>`	`kthLargest(Collection<? extends T> c, int k)` Returns `Nullable.empty()` if the specified `Array/Collection` is `null` or empty, or its length/size is less than `k`.
`static <T> u.Nullable<T>`	`kthLargest(Collection<? extends T> c, int k, Comparator<? super T> cmp)` Returns `Nullable.empty()` if the specified `Array/Collection` is `null` or empty, or its length/size is less than `k`.
`static <T extends Comparable<? super T>> u.Nullable<T>`	`kthLargest(T[] a, int k)` Returns `Nullable.empty()` if the specified `Array/Collection` is `null` or empty, or its length/size is less than `k`.
`static <T> u.Nullable<T>`	`kthLargest(T[] a, int k, Comparator<? super T> cmp)` Returns `Nullable.empty()` if the specified `Array/Collection` is `null` or empty, or its length/size is less than `k`.
`static u.OptionalInt`	`lastIndexOf(Collection<?> c, Object objToFind)`
`static u.OptionalInt`	`lastIndexOf(Object[] a, Object objToFind)`
`static u.OptionalByte`	`max(byte... a)` Returns `OptionalByte.empty()` if the specified `Array/Collection` is `null` or empty.
`static u.OptionalChar`	`max(char... a)` Returns `OptionalChar.empty()` if the specified `Array/Collection` is `null` or empty.
`static <T extends Comparable<? super T>> u.Nullable<T>`	`max(Collection<? extends T> c)` Returns `Nullable.empty()` if the specified `Array/Collection` is `null` or empty.
`static <T> u.Nullable<T>`	`max(Collection<? extends T> c, Comparator<? super T> cmp)` Returns `Nullable.empty()` if the specified `Array/Collection` is `null` or empty.
`static u.OptionalDouble`	`max(double... a)` Returns `OptionalDouble.empty()` if the specified `Array/Collection` is `null` or empty.
`static u.OptionalFloat`	`max(float... a)` Returns `OptionalFloat.empty()` if the specified `Array/Collection` is `null` or empty.
`static u.OptionalInt`	`max(int... a)` Returns `OptionalInt.empty()` if the specified `Array/Collection` is `null` or empty.
`static <T extends Comparable<? super T>> u.Nullable<T>`	`max(Iterator<? extends T> iter)` Returns `Nullable.empty()` if the specified `Array/Collection` is `null` or empty.
`static <T> u.Nullable<T>`	`max(Iterator<? extends T> iter, Comparator<? super T> cmp)` Returns `Nullable.empty()` if the specified `Array/Collection` is `null` or empty.
`static u.OptionalLong`	`max(long... a)` Returns `OptionalLong.empty()` if the specified `Array/Collection` is `null` or empty.
`static u.OptionalShort`	`max(short... a)` Returns `OptionalShort.empty()` if the specified `Array/Collection` is `null` or empty.
`static <T extends Comparable<? super T>> u.Nullable<T>`	`max(T[] a)` Returns `Nullable.empty()` if the specified `Array/Collection` is `null` or empty.
`static <T> u.Nullable<T>`	`max(T[] a, Comparator<? super T> cmp)` Returns `Nullable.empty()` if the specified `Array/Collection` is `null` or empty.
`static <T> u.Nullable<T>`	`maxBy(Collection<? extends T> c, Function<? super T,? extends Comparable> keyMapper)` Returns `Nullable.empty()` if the specified `Array/Collection` is `null` or empty.
`static <T> u.Nullable<T>`	`maxBy(Iterator<? extends T> iter, Function<? super T,? extends Comparable> keyMapper)` Returns `Nullable.empty()` if the specified `Array/Collection` is `null` or empty.
`static <T> u.Nullable<T>`	`maxBy(T[] a, Function<? super T,? extends Comparable> keyMapper)` Returns `Nullable.empty()` if the specified `Array/Collection` is `null` or empty.
`static <T extends Comparable<? super T>> u.Nullable<T>`	`median(Collection<? extends T> c)` Returns `Nullable.empty()` if the specified `Array/Collection` is `null` or empty.
`static <T> u.Nullable<T>`	`median(Collection<? extends T> c, Comparator<? super T> cmp)` Returns `Nullable.empty()` if the specified `Array/Collection` is `null` or empty.
`static <T extends Comparable<? super T>> u.Nullable<T>`	`median(T[] a)` Returns `Nullable.empty()` if the specified `Array/Collection` is `null` or empty.
`static <T> u.Nullable<T>`	`median(T[] a, Comparator<? super T> cmp)` Returns `Nullable.empty()` if the specified `Array/Collection` is `null` or empty.
`static <T> u.Nullable<T>`	`medianBy(Collection<? extends T> c, Function<? super T,? extends Comparable> keyMapper)` Returns `Nullable.empty()` if the specified `Array/Collection` is `null` or empty.
`static <T> u.Nullable<T>`	`medianBy(T[] a, Function<? super T,? extends Comparable> keyMapper)` Returns `Nullable.empty()` if the specified `Array/Collection` is `null` or empty.
`static u.OptionalByte`	`min(byte... a)` Returns `OptionalByte.empty()` if the specified `Array/Collection` is `null` or empty.
`static u.OptionalChar`	`min(char... a)` Returns `OptionalChar.empty()` if the specified `Array/Collection` is `null` or empty.
`static <T extends Comparable<? super T>> u.Nullable<T>`	`min(Collection<? extends T> c)` Returns `Nullable.empty()` if the specified `Array/Collection` is `null` or empty.
`static <T> u.Nullable<T>`	`min(Collection<? extends T> c, Comparator<? super T> cmp)` Returns `Nullable.empty()` if the specified `Array/Collection` is `null` or empty.
`static u.OptionalDouble`	`min(double... a)` Returns `OptionalDouble.empty()` if the specified `Array/Collection` is `null` or empty.
`static u.OptionalFloat`	`min(float... a)` Returns `OptionalFloat.empty()` if the specified `Array/Collection` is `null` or empty.
`static u.OptionalInt`	`min(int... a)` Returns `OptionalInt.empty()` if the specified `Array/Collection` is `null` or empty.
`static <T extends Comparable<? super T>> u.Nullable<T>`	`min(Iterator<? extends T> iter)` Returns `Nullable.empty()` if the specified `Array/Collection` is `null` or empty.
`static <T> u.Nullable<T>`	`min(Iterator<? extends T> iter, Comparator<? super T> cmp)` Returns `Nullable.empty()` if the specified `Array/Collection` is `null` or empty.
`static u.OptionalLong`	`min(long... a)` Returns `OptionalLong.empty()` if the specified `Array/Collection` is `null` or empty.
`static u.OptionalShort`	`min(short... a)` Returns `OptionalShort.empty()` if the specified `Array/Collection` is `null` or empty.
`static <T extends Comparable<? super T>> u.Nullable<T>`	`min(T[] a)` Returns `Nullable.empty()` if the specified `Array/Collection` is `null` or empty.
`static <T> u.Nullable<T>`	`min(T[] a, Comparator<? super T> cmp)` Returns `Nullable.empty()` if the specified `Array/Collection` is `null` or empty.
`static <T> u.Nullable<T>`	`minBy(Collection<? extends T> c, Function<? super T,? extends Comparable> keyMapper)` Returns `Nullable.empty()` if the specified `Array/Collection` is `null` or empty.
`static <T> u.Nullable<T>`	`minBy(Iterator<? extends T> iter, Function<? super T,? extends Comparable> keyMapper)` Returns `Nullable.empty()` if the specified `Array/Collection` is `null` or empty.
`static <T> u.Nullable<T>`	`minBy(T[] a, Function<? super T,? extends Comparable> keyMapper)` Returns `Nullable.empty()` if the specified `Array/Collection` is `null` or empty.
`static <T> boolean`	`padLeft(List<T> list, int minLen, T objToAdd)`
`static <T> boolean`	`padRight(Collection<T> c, int minLen, T objToAdd)`

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

Method Detail

min
```
@SafeVarargs
public static u.OptionalChar min(char... a)
```
Returns OptionalChar.empty() if the specified Array/Collection is null or empty.

Parameters:

a -

Returns:

min
```
@SafeVarargs
public static u.OptionalByte min(byte... a)
```
Returns OptionalByte.empty() if the specified Array/Collection is null or empty.

Parameters:

a -

Returns:

min
```
@SafeVarargs
public static u.OptionalShort min(short... a)
```
Returns OptionalShort.empty() if the specified Array/Collection is null or empty.

Parameters:

a -

Returns:

min
```
@SafeVarargs
public static u.OptionalInt min(int... a)
```
Returns OptionalInt.empty() if the specified Array/Collection is null or empty.

Parameters:

a -

Returns:

min
```
@SafeVarargs
public static u.OptionalLong min(long... a)
```
Returns OptionalLong.empty() if the specified Array/Collection is null or empty.

Parameters:

a -

Returns:

min
```
@SafeVarargs
public static u.OptionalFloat min(float... a)
```
Returns OptionalFloat.empty() if the specified Array/Collection is null or empty.

Parameters:

a -

Returns:

min
```
@SafeVarargs
public static u.OptionalDouble min(double... a)
```
Returns OptionalDouble.empty() if the specified Array/Collection is null or empty.

Parameters:

a -

Returns:

max
```
@SafeVarargs
public static u.OptionalChar max(char... a)
```
Returns OptionalChar.empty() if the specified Array/Collection is null or empty.

Parameters:

a -

Returns:

max
```
@SafeVarargs
public static u.OptionalByte max(byte... a)
```
Returns OptionalByte.empty() if the specified Array/Collection is null or empty.

Parameters:

a -

Returns:

max
```
@SafeVarargs
public static u.OptionalShort max(short... a)
```
Returns OptionalShort.empty() if the specified Array/Collection is null or empty.

Parameters:

a -

Returns:

max
```
@SafeVarargs
public static u.OptionalInt max(int... a)
```
Returns OptionalInt.empty() if the specified Array/Collection is null or empty.

Parameters:

a -

Returns:

max
```
@SafeVarargs
public static u.OptionalLong max(long... a)
```
Returns OptionalLong.empty() if the specified Array/Collection is null or empty.

Parameters:

a -

Returns:

max
```
@SafeVarargs
public static u.OptionalFloat max(float... a)
```
Returns OptionalFloat.empty() if the specified Array/Collection is null or empty.

Parameters:

a -

Returns:

max
```
@SafeVarargs
public static u.OptionalDouble max(double... a)
```
Returns OptionalDouble.empty() if the specified Array/Collection is null or empty.

Parameters:

a -

Returns:

min
```
public static <T extends Comparable<? super T>> u.Nullable<T> min(T[] a)
```
Returns Nullable.empty() if the specified Array/Collection is null or empty.

Parameters:

a -

Returns: