课程

You've reached new Level!

Hi, Bilaabo! Bilaabo is happy to greet his friend! Today Bilaabo will tell you about operator precedence. But first he will tell you about the operators themselves. What are these operators you speak of? Actually, you're already familiar with them. You just might not have known they are called operators. For example, say we have the expression c = a + b; It has two operators: an addition operator and an assignment operator.

"Hi, Amigo! I came up with a couple of interesting tasks for you." "They can only be completed in IntelliJ IDEA. Take a look at these interesting conditions…"

"Oh, Rishi! Hi!" "Hi, Amigo! How's life?" "Great. Bilaabo has just been telling me a bunch of interesting things about File, and how to work with it." "As it happens, I think I have something to add on this topic." "Really? Then I'm all ears." "Okay, listen up. Java is constantly evolving. Its developers are constantly looking for new ways to do different things more efficiently. In Java 7, they added an alternative to the File class ..."

"Now I'll tell you about some methods that are just as helpful: equals(Object o) & hashCode()." "You've probably already remembered that, in Java, when comparing reference variables the objects themselves aren't compared, but rather the references to the objects." "Yes, I remember that." The equals. "The equals method is the standard solution here ..."

"Hi, Amigo!" "Hi, Diego!" "Good old Diego has prepared several tasks for you:"

"Hi, Amigo!" "Hi, Rishi!" "I'm going to introduce you to the Object class's wait, notify, and notifyAll methods." "Today we'll just get acquainted with them, but we'll come back later and spend more time on this." "Okay." "These methods were invented as part of the thread synchronization mechanism." "Let me remind you that Java has a built-in mechanism for controlling access to shared resources (objects) from different threads ..."

"Hi, Amigo!" "Hi, Kim." "I'm going to tell you about the clone() method." "The point of this method is to clone an object, or in other words, to create a clone/copy/duplicate of the object." "When this method is called, the Java virtual machine creates and returns a duplicate of the object it is called on. The Object class's implementation of the clone method is very primitive: only one new object is created, and the values of the original object's ..."

"Hi, Amigo!" "I just found a magazine from 2014. Can you imagine?" "And it has a set of cloning tasks that are older than dirt. Check it out:"

"Hi, Amigo!" "I just decided to discuss the finalize() method with you." "If you remember, finalize() is a special method that is called by an object before
the garbage collector destroys it." "This method's main purpose is to free up used external non-Java resources by closing files, I/O streams, and so on." "Unfortunately, this method doesn't live up to our expectations. The Java virtual machine can postpone destroying an object ..."

"Hi, Amigo!" "I thought you had already figured out finalize." "That's what I thought. But now we have this try-with-resources statement." "Crap. I'm never going to finish learning Java at this rate. I think I understand everything, and then you show up!" "Don't fret like that—you'll rupture an oil line. Instead, figure out these tasks:"

"Hi, Amigo!" "Now it's time for the main event. We'll get acquainted with the Class class and touch on Reflection. As you probably already realized, everything in Java is an object. And what does an object need? What does each object have that defines what it's all about?" "A class!" "Right! Well done. Each object has a class. But getting back to objects... Some objects entirely contain an entity, while others simply help manage it ..."