1.使窗体位于屏幕中心

Dimension welcomeScreen=Toolkit.getDefaultToolkit().getScreenSize();
        int x=(welcomeScreen.width-this.getSize().width)/2;
        int y=(welcomeScreen.height-this.getSize().height)/2;
        this.setBounds(x, y, 500, 400);

2.设置文件过滤器

private void jButton1ActionPerformed(java.awt.event.ActionEvent evt) {                                         
        // TODO add your handling code here:
        jFileChooser1.setFileFilter(new FileFilter() {

            @Override
            public boolean accept(File f) {
                return f.getName().toLowerCase().endsWith(".txt")||f.isDirectory(); //To change body of generated methods, choose Tools | Templates.
            }

            @Override
            public String getDescription() {
                return ".txt 文件"; //To change body of generated methods, choose Tools | Templates.
            }
        });
        jFileChooser1.showOpenDialog(this);
    }                              

Java Swing学习小结