How to read text from a file after opening with JFileChooser

Question

I am using Java in Eclipse trying to write a program that lets me choose a file and then reads what's in it. So far, all I can get it to do is print out the name of the file itself, not the text inside it. Ideally, I would like to it find certain strings and only display those, but I figure I need to figure out how to get it to read anything at all before I get to that step. Here's what I have.

import java.awt.FlowLayout;
import java.awt.event.*;
import java.io.File;
import javax.swing.JButton;
import javax.swing.JFileChooser;
import javax.swing.JFrame;

public class MainFrame extends JFrame implements ActionListener{

    JButton button;
    
    MainFrame(){        
        this.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
        this.setLayout(new FlowLayout());
        
        button = new JButton("Select File");
        button.addActionListener(this);
        
        this.add(button);
        this.pack();
        this.setVisible(true);
    }
    
    @Override
    public void actionPerformed(ActionEvent e) {
        
        if(e.getSource()==button) {
            
            JFileChooser fileChooser = new JFileChooser();
            
            fileChooser.setCurrentDirectory(new File("/Users/ccampbell/Desktop")); //sets current directory
            
            int response = fileChooser.showOpenDialog(null); //select file to open
            //int response = fileChooser.showSaveDialog(null); //select file to save
            
            if(response == JFileChooser.APPROVE_OPTION) {
                File file = new File(fileChooser.getSelectedFile().getAbsolutePath());
                System.out.println(file);