Getting Started with Java-mastering the wrong piece of the Eclipse Java compiler level dose not match the version of the installed Java project

first, the error phenomenon.

The Java Project displays red, and a red error is reported in the reference package in the class, and the following error message is displayed below eclipse

Second, the cause of the error.

It is clear from the literal meaning that the Java version is incorrect.

Third, the solution.

3.1 Right-click Project "Properties" on the left side of the "Properties" window that pops up.

3.2 Click Project Facets to open the Project Facets page and change the Java version

All right, let's not forget to click Apply at the end.

Getting Started with Java-mastering the wrong piece of the Eclipse Java compiler level dose not match the version of the installed Java project