Explain the difference between abstract classes and interfaces in Java

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In the Java language, abstract class and interface are two mechanisms that support abstract class definition. It is precisely because of the existence of these two mechanisms that Java is endowed with powerful object-oriented capabilities. Abstract class and interface have great similarity in support of abstract class definition, and can even replace each other. Therefore, many developers choose abstract class and interface at will when defining abstract classes. In fact, there are still great differences between the two. Their choice even reflects whether the understanding of the essence of the problem field and the understanding of the design intention are correct and reasonable. This paper will analyze the differences between them, trying to provide developers with a basis for choosing between them. Understand that abstract classes abstract class and interface are used to abstract classes in the Java language (the abstract class in this article is not translated from abstract class. It represents an abstract body, and abstract class is a method used to define abstract classes in the Java language. Please pay attention to distinguish). So what is an abstract class and what benefits can it bring us?