确保运行时的主类所在的项目与包含断点的类所在的项目相同。如果不是，请确保两个项目都在运行配置的类路径中，并且出现在任何jar和类文件夹之前。

这招对我很管用:

在窗口——>首选项——> Java——>编译器——>类文件生成下，所有选项都必须为True。 在build.xml <javac>任务中使debug="true"。 通过ant生成的war在tomcat中部署应用程序 在Debug模式下重新启动Tomcat

尝试更改您使用的jre。请设置JDK目录下的jre。

We have very useful information to solve this problem already, but in my specific case, the problem was that as I did an update to my project from the repository, new classes were generated with the compiled source from the newest code. The problem is that I forgot to change the versions of the projects in my POM files and as the breakpoints were set on the new code and the POM files were still pointing to old versions that were available on the JAR files of a previous compilation, the classes from the JAR files were chosen and not the classes from the new code.

在恢复中，为了解决这个问题，我只需要更新主项目的POM文件的版本，清理并重新编译源代码，最后刷新环境。我希望这能对其他人有用。

If someone is trying to debug Java's source code, then, this is the only solution that worked for me. Most of the above answers talk about setting the Compiler option to generate line numbers.But, if want to debug Java's source code (say java.util.HashMap), then the above options may not work for you. This is because , the project from where you intend to debug the source code is having the Java Build Path --> Library --> JRE System Library pointing to the jre jar instead of the jdk jar. The classes bundled inside jre jar have already been pre-compiled with a specific option, that will not honor the Compiler option settings. Solution, is to reconfigure your project to have the JRE System Library point to the jdk jar. The classes inside your jdk jar will honour the Compiler option settings. So, once you update your project's JRE System Library to point to the jdk jar, debug on Java source code will start working.

如果您确实指出了您正在使用的eclipse版本和技术(例如，Java JDT，或面向Java的AJDT，或c++ CDT)，这将有所帮助。

在Java方面，我猜想您的“勾选编译器选项中的复选框”指的就是这个

在“窗口—>首选项—> Java—>编译器—>类文件生成”下，所有“类文件”生成选项都设置为True:

(1)添加可变属性， (2) addline number， (3)添加源文件名， (4)保存未使用的局部变量。

您的项目是否只在全局级别(windows Preferences)或在项目特定级别检查这些?

你确定打开的类(你试图在上面设置断点):

是您的源代码之一(并且不是来自第三方库) 是。java，而不是。class?

尝试清理所有内容并重新构建所有内容，检查潜在的jar冲突。