java输出完全限定名,在Java中使用完全限定名称和导入之间的区别-优快云博客

博客探讨了Java中使用内联导入（完全限定名）和普通导入在性能、内存、编译时间等方面是否存在差异。指出应主要关注可读性，多数情况下普通导入更优，特殊情况内联导入可避免混淆。还通过字节码证明二者性能相同。

摘要生成于 C知道，由 DeepSeek-R1 满血版支持，前往体验 >

Are there any differences using an "inline import" (a fully qualified name) and normal import in terms of performance, memory, compile-time, etc. in Java?

chooser.setCurrentDirectory(new java.io.File("."));

and

import java.io.File;

...

chooser.setCurrentDirectory(new File("."));

解决方案

The main thing you should focus in is readability. I find the second one more readable.

In rare cases, I prefer the second approach. Let's consider the following scenario: For some reason, I wrote a class and named it File. I typed File file = new File(...) and my IDE auto-imported the java.io.File for me. But I don't want that kind of object, I want my File class. So instead of importing the correct class, I prefer inline-import it, just that other users won't get confused with the Java's File class.

Regarding the performance, they're exactly the same, and here's the proof -

This is the bytecode generated for the first snippet:

public class java8.tests.General {

public java8.tests.General();

Code:

0: aload_0

1: invokespecial #1 // Method java/lang/Object."":()V

4: return

public static void main(java.lang.String[]);

Code:

0: new #2 // class javax/swing/JFileChooser

3: dup