Question

Write a program to: (a) Print the name, priority, and Thread group of the thread. (b) Change the name of the current thread to "JAVA". (c) Display the details of the current thread.

Short answer

Use `Thread.currentThread()` to get and modify details of the current thread, including its name, priority, and group.

Step-by-step solution

Include necessary library

You need to first import the required package for threading. In Java, we need to import the `java.lang.Thread` class since by default `java.lang` is imported in every Java program.

Define main method

Every Java application needs a `main` method to run. Define the `main` method inside your class to contain the main execution logic.

Obtain Reference to Current Thread

Use the `Thread.currentThread()` method to get a reference to the currently executing thread. This will allow you to access the properties and perform operations on the current thread.

Print Thread Details

Retrieve and print the current thread's name, priority, and its thread group using the methods `getName()`, `getPriority()`, and `getThreadGroup().getName()`. Use `System.out.println` to display each attribute.

Change Thread Name

Use the `setName()` method on the current thread instance to change its name to "JAVA". This will rename the current thread from its original name.

Display Modified Thread Details

After changing the thread name, print the updated details of the thread to confirm the name has been changed. Again, use `getName()`, `getPriority()`, and `getThreadGroup().getName()` to obtain and display these details.

Key concepts

Java main method

In Java, the main method is the entry point for any standalone application. It is essential for the execution of any Java program. This method is always defined with the signature `public static void main(String[] args)`.
Here is a breakdown:

• public: This keyword allows Java to execute this method from outside classes or packages.
• static: It permits Java to invoke this method without creating an instance of the class.
• void: This denotes that the method does not return any value.
• main: This is the name of the method that is searched by the JVM as the start point.
• String[] args: This is an array of strings passed as parameters for command-line arguments.

The "main" method must be placed in one class, and typically, it houses the code necessary for defining your program's behavior upon startup. It's pivotal for managing the primary thread that executes your application.

Thread priority

Thread priority in Java is a mechanism to influence the execution order of threads. Each thread has a priority value between 1 (MIN_PRIORITY) and 10 (MAX_PRIORITY), with the default being 5 (NORM_PRIORITY).
The concept behind thread priority is to let the thread scheduler know the importance of a particular thread over another. However, remember that this is merely a suggestion to the scheduler, and behavior can vary across different platforms.
To set a thread's priority, you can use the `setPriority(int priority)` method on a `Thread` object. Example: ```java Thread thread = new Thread(); thread.setPriority(7); ```

• This example sets the priority of `thread` to 7.

Note that altering thread priorities is seldom necessary and should be done cautiously, as excessive dependence on priorities can make the program less portable and predictable.

Thread group

A Thread Group in Java is a vital part of thread management, serving as a mechanism to group multiple threads into a single unit. This concept allows you to organize threads into distinct categories and manage them collectively.
When you create a new thread, it is automatically included in the same thread group as the creator thread unless specified otherwise. Each thread group can also include other thread groups, forming a tree structure.
Here's how you find the thread group of a thread:

• Use the `getThreadGroup()` method.
• To get the name of the thread group, chain `.getName()` after `getThreadGroup()`.

Example: ```java ThreadGroup group = Thread.currentThread().getThreadGroup(); System.out.println("Thread Group: " + group.getName()); ``` Managing thread groups can help in bulk operations, such as suspending or resuming all threads within a group, which can be beneficial in complex applications.

Thread name change

Changing the name of a thread in Java is straightforward and a very practical feature for debugging and making your code more readable. By default, a thread is assigned a name by the JVM, like `Thread-0`, `Thread-1`, and so on.
You can change the name of a thread via the `setName(String name)` method. This doesn't affect the thread's execution but makes it easier to identify the thread during debugging.
Here is an example of how to change a thread's name: ```java Thread.currentThread().setName("JAVA"); System.out.println("New Thread Name: " + Thread.currentThread().getName()); ```

• This snippet modifies the current thread's name to "JAVA".
• Using `getName()`, you can retrieve the thread's updated name.

Renaming threads is particularly useful when you have multiple threads executing concurrent tasks and you need to log their activities separately. It can significantly enhance the clarity of your threads' roles.