Section 1: IntSummaryStatistics Class

The IntSummaryStatistics class is instrumental for the analysis and management of statistical data. It processes Integer objects and gathers essential insights such as sum and average.

Basics:

IntSummaryStatistics is primarily designed to work with streams, though it can also accept values via lists and iterators.

To instantiate an IntSummaryStatistics object, use the following syntax:

IntSummaryStatistics stats = new IntSummaryStatistics();

Methods:

Here are a few notable methods within the IntSummaryStatistics class. You can find additional methods online for a comprehensive understanding.

• accept(int value): Adds an integer to the statistics.
• getAverage(): Retrieves the average of all integers processed.
• getCount(): Returns the count of integers processed.

Example:

IntSummaryStatistics data = new IntSummaryStatistics();

List<Integer> nums = Arrays.asList(1, 2, 3, 4, 5, 6, 7, 8, 9, 10);

Iterator<Integer> iter = nums.listIterator();

while (iter.hasNext()) {

data.accept(iter.next());

}

System.out.println("Average: " + data.getAverage());

System.out.println("Count: " + data.getCount());

Output:

Average: 5.5

Count: 10

Section 2: OptionalDouble Class

The OptionalDouble class serves as a container that may or may not hold a double value.

Basics:

If a double exists within the OptionalDouble, various methods can confirm its presence. It's advised to avoid identity-sensitive operations due to its value-based nature.

To create an OptionalDouble, utilize its static methods:

• To create without a value: OptionalDouble emptyVal = OptionalDouble.empty();
• To create with a value: OptionalDouble filledVal = OptionalDouble.of(15.0);

Methods:

Here are several methods for OptionalDouble:

• isPresent(): Checks if a value exists.
• getAsDouble(): Returns the contained value or throws an exception if absent.

Example:

OptionalDouble val2 = OptionalDouble.of(15.0);

System.out.println("A value is present: " + val2.isPresent());

System.out.println("Double contained: " + val2.getAsDouble());

Output:

A value is present: true

Double contained: 15.0

Section 3: SimpleTimeZone Class

The SimpleTimeZone class, a subclass of TimeZone, is tailored for the Gregorian calendar and incorporates daylight saving time rules.

Basics:

This class is essential for handling time and dates, especially concerning daylight saving time adjustments. You can retrieve different time zone offsets relative to UTC.

Basic Syntax:

SimpleTimeZone zone = new SimpleTimeZone(rawOffset, timeZoneID);

Methods:

Key methods include:

• clone(): Produces a copy of the SimpleTimeZone object.
• usesDaylightTime(): Indicates if the time zone observes daylight saving time.

Section 4: StringTokenizer Class

The StringTokenizer class facilitates breaking down a string into tokens (segments of the string).

Basics:

To use StringTokenizer, initiate it with a string and optionally specify delimiters. Tokens can then be accessed using the nextToken() method.

Example:

StringTokenizer tokenizer = new StringTokenizer("Tandrew is legit");

while (tokenizer.hasMoreTokens()) {

System.out.println(tokenizer.nextToken());

}

Output:

Tandrew

is

legit

Section 5: Hashtable Class

The Hashtable class links keys to specific values, forming key-value pairs.

Basics:

In a Hashtable, each key is hashed to determine where its corresponding value is stored.

Basic Syntax:

Hashtable<keyType, valType> table = new Hashtable<keyType, valType>();

Methods:

Key methods include:

• elements(): Returns an enumeration of all values in the table.
• get(Object key): Retrieves the value associated with the specified key.

Section 6: TimerTask Class

The TimerTask class allows for scheduled execution of tasks.

Basics:

Working alongside the Timer class, a TimerTask can be scheduled to perform actions after a specified delay.

Example:

TimerTask task = new TimerTask() {

@Override

public void run() {

System.out.println("Task executed!");

}

};

Timer timer = new Timer();

timer.schedule(task, 10000); // Executes after 10 seconds