Pass text to jTextArea class from another class(different layers)

[jeata]

I have two classes. One is a GUI with a textArea, a jButton and a method to set text in the text field. The other contains just one simple void method called setString which needs to pass a string to the first class. I think everything is as it should be, but somehow it gives me a bunch of exceptions

Here's the first class(The GUI)

private JTextArea getJTextArea() {
		if (jTextArea == null) {
			jTextArea = new JTextArea();
			jTextArea.setBounds(new Rectangle(11, 6, 417, 160));
		}
		return jTextArea;
	}

	/**
	 * This method initializes getParts	
	 * 	
	 * @return javax.swing.JButton	
	 */
	private JButton getGetParts() {
		if (getParts == null) {
			getParts = new JButton();
			getParts.setBounds(new Rectangle(232, 174, 193, 25));
			getParts.setText("SET TEXT");
			getParts.addActionListener(new java.awt.event.ActionListener() {
				public void actionPerformed(java.awt.event.ActionEvent e) {
					gc1.setString();
					
				}
			});
		}
		return getParts;
	}

Here's the second

  public void setString()
    {
    	 gui1.setTextMainField("THIS IS PASSED FROM SECOND CLASS");
    }

[Norm]

it gives me a bunch of exceptions

Please copy and paste here the full text of the error messages.