Get values from instantiated GUI classes within a desktoppane

Question

I am instantiating a class with jtextfield on it and place it in a desktoppane. If for example, I instantiated this class 5 times, how could I get the values from the textfields of different windows? The only values that were returned are from the last instantiated class even I put focus on the first to fourth windows.

Child ch;
JInternalFrame ji;

ch=new Child();

public void createWindow(){
    ji = new JInternalFrame(ch.getTitle(),true,true,true,false);
    ji.setName(""+x);
    ji.add(ch.getRootPane());
    ji.setLocation(20*x, 20*x);

    jDesktopPane1.add(ji);

    ji.pack();
    ji.setVisible(true);

    x++;
}

public void showInput(){
    System.out.println(ch.jTextField1.getText());
    System.out.println(ch.jTextField2.getText());
}