为什么打开文件的时候会出现空指针异常呢，弹出窗体没有问题，但是打开文件就会空指针

[笑的太自信]

package cn.itcast.swing.demo;

import java.awt.BorderLayout;
import java.awt.EventQueue;

import javax.swing.JDialog;
import javax.swing.JFileChooser;
import javax.swing.JFrame;
import javax.swing.JPanel;
import javax.swing.border.EmptyBorder;
import javax.swing.filechooser.FileNameExtensionFilter;
import javax.swing.JMenuBar;
import javax.swing.JMenuItem;
import javax.swing.JMenu;
import java.awt.event.ActionListener;
import java.awt.event.ActionEvent;
import java.awt.event.MouseAdapter;
import java.awt.event.MouseEvent;
import java.io.BufferedReader;
import java.io.File;
import java.io.FileNotFoundException;
import java.io.FileReader;
import java.io.IOException;

import javax.swing.JScrollPane;
import javax.swing.JTextArea;

public class MyMenu extends JFrame {

protected static final String LINE_SEPARATOR = System.getProperty("line.separator");
private JPanel contentPane;
private JFileChooser chooser;
private JDialog dialog;
private JMenuItem menuItem;
private JTextArea textArea;

/**
* Launch the application.
*/
public static void main(String[] args) {
EventQueue.invokeLater(new Runnable() {
public void run() {
try {
MyMenu frame = new MyMenu();
frame.setVisible(true);
} catch (Exception e) {
e.printStackTrace();
}
}
});
}

/**
* Create the frame.
*/
public MyMenu() {
setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
setBounds(100, 100, 636, 518);
contentPane = new JPanel();
contentPane.setBorder(new EmptyBorder(5, 5, 5, 5));
setContentPane(contentPane);
contentPane.setLayout(null);

JMenuBar menuBar = new JMenuBar();
menuBar.setBounds(0, 0, 622, 33);
contentPane.add(menuBar);

JMenu menu = new JMenu("\u6587\u4EF6");
menuBar.add(menu);

JMenuItem menuItem_1 = new JMenuItem("\u6253\u5F00");
menuItem_1.addActionListener(new ActionListener() {
public void actionPerformed(ActionEvent e) {

chooser = new JFileChooser();// 文件选取

// FileNameExtensionFilter filter = new FileNameExtensionFilter("JPG & GIF Images", "jpg", "gif");
// chooser.setFileFilter(filter);

int returnVal = chooser.showOpenDialog(MyMenu.this);
if(returnVal == JFileChooser.CANCEL_OPTION) {
System.out.println("没有选取文件，取消了");
return;
}

File file = chooser.getSelectedFile();
BufferedReader bufr = null ;
String line = null ;
try {
bufr = new BufferedReader(new FileReader(file));
line = null;
while((line=bufr.readLine())!=null) {
textArea.append(line+LINE_SEPARATOR);//这里空指针异常
}
bufr.close();
} catch (IOException e1) {

e1.printStackTrace();
}

}
});
menu.add(menuItem_1);

JScrollPane scrollPane = new JScrollPane();
scrollPane.setBounds(0, 31, 622, 450);
contentPane.add(scrollPane);

JTextArea textArea_1 = new JTextArea();
scrollPane.setViewportView(textArea_1);
}
}

[qybao]

textArea没有new，所以是空指针 是不是要用textArea_1？这个倒是new了

[usecf]

File file = chooser.getSelectedFile(); BufferedReader bufr = null ; String line = null ; try { bufr = new BufferedReader(new FileReader(file)); 打印下你的file和bufr看看有值没

[笑的太自信]

引用 2 楼 usecf的回复:

File file = chooser.getSelectedFile(); BufferedReader bufr = null ; String line = null ; try { bufr = new BufferedReader(new FileReader(file)); 打印下你的file和bufr看看有值没

line和bufr都有值，我把textArea.append()改成输出语句，就没有空指针异常了

[笑的太自信]

引用 1 楼 qybao的回复:

textArea没有new，所以是空指针 是不是要用textArea_1？这个倒是new了

textArea我刚new了一下，异常没有了，但是啥也没打印出来

[笑的太自信]

找到原因了，把下边的new的textArea_1放在动作监听器的上边就可以了