Adding JPanel from another class to JPanel in JFrame

Question

I can\'t get my JFrame from main class to display JPanel from another class. Everything compiles without errors.

JFrameTest.java:

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Answer 1

First to answer your question, you need to add an instance of your panel to the frame with something like this in your JFrameTest constructor:

add(new JPanelOne());

You also need to add your button directly to JPanelOne itself:

public class JPanelOne extends JPanel {   

  public JPanelOne() {   
    JButton button = new JButton("test");   
    add(button);   
  }   
}

Second, I believe there is a problem with these lines of code:

    FlowLayout mainLayout = new FlowLayout(); 
    // snip...
    setLayout(mainLayout); 

    JPanel panelMain = new JPanel(mainLayout); 

Each container should have its own instance of a layout manager. Otherwise your GUI will do strange things:

setLayout(new FlowLayout());
JPanel panelMain = new JPanel(mainLayout);