java – Can’t import javax.swing in Eclipse (even with new jdk)

Can’t import javax.swing in Eclipse 2024-09 for a JOptionPane (or any other swing import).

I’ve tried clean install eclipse with the default jre, I’ve uninstalled it and installed it two other times, one with java jdk 23 and another one with jdk 21, I’ve checked the installed JREs section in the Window > Preferences > Java > Installed JREs section every time and also checked the installed libraries in the Project > Properties > Java Build Path section as said in other questions. I don’t know what I’m doing wrong and I’ve been troubleshooting this all day, need help.