How can I solve Void cannot be dereferenced?

[akasekaihime]

We are asked to create a calculator but before I do that I must correct the codes given in order for me to know what I must add in my calculator but I do not know how to solve the "void cannot be referenced " error...how can I do that?

here's the code that I made....the error is line 80 and 87

import javax.swing.*;
import java.awt.*;
import java.awt.event.*;
public class Button extends JFrame implements ActionListener
{
	private static int width=600;
	private static int height=300;
	private JLabel[] labelJL = new JLabel[3];
	private JTextField[] textJT = new JTextField[3];
	private JButton[] AddClearExit = new JButton[3];
	public Button()
	{
		Container pane = getContentPane();
		setTitle("USING BUTTON EVENT");
		setSize(width,height);
		setLayout(null);

		labelJL[0] = new JLabel("FIRST NUMBER",0);
		labelJL[0].setLocation(150,20);
		labelJL[0].setSize(100,20);
		pane.add(labelJL[0]);

		textJT[0] = new JTextField();
		textJT[0].setLocation(260,20);
		textJT[0].setSize(200,20);
		pane.add(textJT[0]);

		labelJL[1] = new JLabel("SECOND NUMBER",0);
		labelJL[1].setLocation(150,50);
		labelJL[1].setSize(100,20);
		pane.add(labelJL[1]);

		textJT[1] = new JTextField();
		textJT[1].setLocation(260,50);
		textJT[1].setSize(200,20);
		pane.add(textJT[1]);

		labelJL[2] = new JLabel("Total Sum",0);
		labelJL[2].setLocation(150,80);
		labelJL[2].setSize(100,20);
		pane.add(labelJL[2]);

		textJT[2] = new JTextField();
		textJT[2].setLocation(260,80);
		textJT[2].setSize(200,20);
		textJT[2].setEditable(false);
		pane.add(textJT[2]);

		AddClearExit[0] = new JButton("Sum");
		AddClearExit[0].setLocation(50,150);
		AddClearExit[0].setSize(150,20);
		AddClearExit[0].addActionListener(this);
		pane.add(AddClearExit[0]);

		AddClearExit[1] = new JButton("Clear");
		AddClearExit[1].setLocation(210,150);
		AddClearExit[1]. setSize(150,20);
		AddClearExit[1].addActionListener(this);
		pane.add(AddClearExit[1]);

		AddClearExit[2] = new JButton("Exit");
		AddClearExit[2].setLocation(370,150);
		AddClearExit[2].setSize(150,20);
		AddClearExit[2].addActionListener(this);
		pane.add(AddClearExit[2]);
		setVisible(true);
		setDefaultCloseOperation(EXIT_ON_CLOSE);
	}
		public void actionPerformed(ActionEvent ae)
		{
			String temp = "";
			long fn=0, sn=0;
	try
	{
		fn=Long.parseLong(textJT[0].getText());
		sn=Long.parseLong(textJT[0].getText());
	}
		catch (Exception ne)
		{
		for(int x=0;x<3;textJT[x].setText(temp).x++);

		}
			if(ae.getActionCommand().equals("Sum"))
				temp+=sum(fn,sn);
				if(ae.getActionCommand().equals("Clear"))

				for(int x=0;x<3;textJT[x].setText(temp).x++);
				if(ae.getActionCommand().equals("Exit"))
					dispose();
					textJT[2].setText(temp);
	}
	public long sum(long x,long y)
	{
		return x+y;
	}
	public static void main (String args[])
	{
		new Button();
	}
		}

thank you for the help......

[JamesCherrill]

for (int x=0;x<3;textJT[x].setText(temp).x++);

you probably meant

for (int x=0;x<3;x++)  textJT[x].setText(temp);

ps: many people would prefer

for (int x=0;x<3;x++) {
   textJT[x].setText(temp);
}