Java报错合集

1.  创建 Java 项目后新建 Class，出现报错：The project was not built...

fig-1. The project was not built...

👌 解决方法：单击项目名称，Properties - Java Build Path - Libraries 下点击 JRE System Library, 选择 JRE-1.1

2. 继承 JFrame 时报错：The type 'JFrame' is not API...

fig-2. The type 'JFrame' is not API...

👌 解决方法：修改eclipse的错误级别设置,

Windows -> Preferences -> Java -> Compiler -> Errors/Warnings -> Deprecated and restricted API -> Forbidden reference (access rules): -> 改为 warning

⚠️ 只是将报错改为warning，可能仍存在问题

👌 解决方法：右键点击 JRE System Library... - Build Path - Configure Build Path

选择 JRE System Library[OSGI]... ，选择 remove 进行移除

点选右边的 Add Library，双击第一个 JRE System Library，默认 Finish