IntelliJ IDEA one-line function formatting

Question

IntelliJ keeps formatting this:

public void addElement(Element elem) {
    this.elements.add(elem);
}

into this:

public voi         


        

Answer 1

below is the shortcut for Merge multiple lines into a line -

Ctrl+Shift+J

Answer 2

Look in Preferences (or Settings), Editor, General, Code Folding, Collapse by default, One-line methods