why its coming like this?
Maybe you need to install the JDK?
Check whether JAVA_HOME environment variable is set to a folder, where you installed JDK. On Windows 10, click Notification icon in the bottom right corner, select “All settings”, then select “System”, in the bottom left corner find “About”, then on the right panel select “Advanced system settings”, then choose “Advanced” tab, at the bottom find “Environment variables…” If there is no such variable, create it. if there is no JDK on your machine, install it. Do not delete the paths that already exist
Yet you should check whether in Path environment variable there is a path to a bin folder inside a folder with JDK
If all is already set but still it doesn’t work, then check if IDEA knows about installed JDK. Open IDEA, click File → Project Structure → Project settings → Project and check SDK field