10 most popular Java classes (conversion) and 10 popular java classes

10 most popular Java classes (conversion) and 10 popular java classes

Original article: http://www.csdn.net/article/2012-06-04/2806277

Every Java programmer has his/her own Java class table. This table does not have strict rules or rules to follow. It depends entirely on the Java project you are involved in. The following classes do not need to be described too much. Java programmers know that they are very popular in the Java World.

1. java. lang. String

If the String class won the championship without dispute, no one will deny this. This is a final class used to create/operate variable string text. It has been available since JDK 1.0.

2. java. lang. System

The use of the System class depends on the project type you work on. You may not have used it in the project, but it is still one of the popular Java classes. This is a tool class that cannot be instantiated. This class is mainly used to access standard input, output, and environment variables. It is available since JDK 1.0.

3. java. lang. Exception

Throwable is a superclass of all errors and exceptions. All exceptions are handled in the Exception class. NullPointerException is the most popular among all exceptions. Exception exceptions are at the top of all Exception hierarchies. It is available since JDK 1.0.

4. java. util. ArrayList

A class that implements the data structure of arrays. This class implements the List interface and is a member of the most popular Java Collection class. The difference between ArrayList and Vector is one of the common questions for beginners. It is also frequently asked during java interviews. It has been introduced since JDK 1.2.

5. java. util. HashMap

A class that implements the data structure of key-value pairs. This class implements the Map interface. Similar to ArrayList and Vector, HashMap and Hashtable are often compared. It is also a popular collection class. As a property-value container, it is often used for data transmission between multiple layers of the application. It has been introduced since JDK 1.2.

6. java. lang. Object

The root class of all Java classes. Each Java class is a subclass of the Object class. It is often used on platforms/frameworks. It contains some important methods, such as equals, hashcode, clone, and toString. It is available since the first day of Java (JDK 1.0)

7. java. lang. Thread

A thread is a single execution sequence. Multiple Threads can exist together to share resources. We can extend the Thread class and create our own Thread. Of course, using Runnable is another option. Whether or not to use this class depends on the needs of your application. There is no need to use threads for a common application. It has been introduced since JDK 1.0.

8. java. lang. Class

A Class is a subclass that directly inherits the Object Class. This class has no constructor, and their objects are loaded by the Java Virtual Machine through the class loader. Most of us may not have used it directly, but I think it is an important class for reflection. It has been introduced since JDK 1.0.

9. java. util. Date

This is the class used to process dates. Sometimes, we think this class should be added with more practical methods. Just like every enterprise-level application will create a date utility unit. It was introduced since JDK 1.0, and then made great changes in JDK. A lot of methods were discarded.

10. java. util. Iterator

This is an interface. It is very popular and used to replace enumeration. This is an easy-to-use unit that uses Iterable for synchronization. It has been introduced since JDK 1.2.

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From: javapapers

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