package com.soft.test;

import java.awt.BorderLayout;
import java.awt.CardLayout;
import java.awt.Color;
import java.awt.FlowLayout;
import java.awt.GridBagConstraints;
import java.awt.GridBagLayout;
import java.awt.GridLayout;
import java.awt.Insets;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;
import
import
import
import

import javax.swing.JButton;
import javax.swing.JFrame;
import javax.swing.JLabel;
import javax.swing.JPanel;
import javax.swing.JTextField;


public class FileSave extends JFrame implements ActionListener{
       private CardLayout card;
       private JPanel jPanelBtn,jPanelSave;
       private JButton saveBtn,inBtn;
       private JTextField nameField;
        public FileSave(){
        init();
        setTitle("         图书管理");
        setSize(600,500);
        setLocationRelativeTo(null);
        setVisible(true );
        setDefaultCloseOperation(DISPOSE_ON_CLOSE);
    }
   
    public void init(){
        jPanelBtn=new JPanel(new FlowLayout(FlowLayout.CENTER));
        saveBtn=new JButton("保存");
        saveBtn.addActionListener(this);
        
        
        inBtn=new JButton("查询");
   
        jPanelBtn.add(saveBtn);
        jPanelBtn.add(inBtn);
        
        jPanelSave=new JPanel(new GridLayout(5,2));
        jPanelSave.setBackground(Color.LIGHT_GRAY);
        //this.setLayout(new GridBagLayout());
        JLabel nameLab=new JLabel("图书名称：");
        JTextField nameField=new JTextField();
        JLabel kindLab=new JLabel("图书类别：");
        JTextField kindField=new JTextField();
        JLabel priceLab=new JLabel("图书位置：");
        JTextField priceField=new JTextField();
        jPanelSave.add(nameLab);
        jPanelSave.add(nameField);        
        jPanelSave.add(kindLab);
        jPanelSave.add(kindField);
        jPanelSave.add(priceLab);
        jPanelSave.add(priceField);
        

   
        
        add(jPanelSave,BorderLayout.CENTER);
        add(jPanelBtn, BorderLayout.SOUTH);
        
        
    }
    public static void main(String[] args) {
        new FileSave();
    }

    @Override
    public void actionPerformed(ActionEvent e) {
        // TODO Auto-generated method stub    saveBtn.addActionListener(new ActionListener() {
        
        
            if(e.getSource()==saveBtn){
            File file=new File("Dora/MyFile");
            String a=nameField.getText();//***********************wrong
            try {    OutputStream out=new FileOutputStream(file);
                    
                    byte []b=a.getBytes();
                    out.write(b);
                    out.close();
            } catch (IOException e2) {
                System.err.println("error");
            }
        
            
        
            
        }
            else if(e.getSource()==inBtn){
                new FileOut();
            }
   
    }
   
}

在scr根目录下创建了一个Dora文件夹，在文件夹里创建了一个文本文档MyFile，按保存的时候执行错误,不知怎么改

private JTextField nameField;
空指针异常，nameField=new JTextField();