Question

From first frame I call another frame:

frame2 fr2 = new frame2();
fr2.setVisible(true);

but when I’m trying to close in the same way – no reaction

frame2 fr2 = new frame2();
fr2.setVisible(false);

All that I do using two buttons on first frame

Answer 1

frame2 fr2 = new frame2();
fr2.setVisible(false);

by this, you are creating a new instance of frame2 and hiding it and you are not doing anything to the frame2 instance that you have already created and hence no reaction

What you should do is create a class field or something similar to hold reference to the instance of frame2 you create at first (when you show it) and then use the same reference and call setVisible(false).

class frame1{
    ...

    private frame2 frame2ref;
    ....


    void foo()
    {
       ....
       frame2ref = new frame2();
       frame2ref .setVisible(true);
       // create and save reference and show frame.
       ...
    }

    void bar()
    {
        ...
        frame2ref.setVisible(false);
        // retrieve reference and hide frame. 
        ...

    }

}