Shulou(Shulou.com)06/03 Report--

This article focuses on "the way to optimize the performance of java development code", interested friends may wish to take a look. The method introduced in this paper is simple, fast and practical. Now let the editor take you to learn "the way to optimize the performance of java development code"!

Goals for code optimization:

Reduce the volume of code

Improve the operation efficiency of the whole system

Code detail optimization

Try to specify the final modifiers for classes and methods

Classes decorated with final are not derivable. In the core API of Java, there are many examples of using final, such as java.lang.String, the whole class is final. Assigning a final modifier to a class makes the class uninheritable, and assigning a final to a method makes it impossible for a method to be overridden. If you specify a class as fianl, all methods of that class are final. The Java compiler will look for opportunities to inline all final methods, which play an important role in improving the efficiency of Java. For more information, see Java runtime optimization. This can improve performance by an average of 50%.

Reuse objects as much as possible

In particular, when using String objects, you should use StringBuilder/StringBuffer instead of string concatenation. Because the Java virtual machine not only takes time to generate objects, it may also take time to garbage collect and process these objects in the future, so generating too many objects will have a great impact on the performance of the program.

Use local objects whenever possible

The parameters passed when the method is called and the temporary variables created in the call are saved in the stack faster, while other variables, such as static variables, instance variables, and so on, are created in the heap and are slow. In addition, the variables created in the stack are gone as the method ends, and no additional garbage collection is required.

Close the stream in time

In the process of Java programming, you must be careful when you connect to the database and operate the I _ big O stream, and close it in time to release resources after using it. Because the operation of these large objects will cause great overhead of the system, a little carelessness will lead to serious consequences.

Minimize the double calculation of variables

So for example, do the following:

For (inti=0;i

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