java JList 添加數(shù)據(jù)后,如何更新啊

更新的話，可以使用自身的validate方法；

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也可以使用SwingUtiltis.updateComponentUI等方法解決。

示例代碼如下：

import?java.awt.*;

import?java.awt.event.*;

import?javax.swing.*;

public?class?LookAndFeelDemo2?extends?JFrame?{

private?JRadioButton?radio1?=?new?JRadioButton("Metal");

private?JRadioButton?radio2?=?new?JRadioButton("Windows");

private?JRadioButton?radio3?=?new?JRadioButton("Motif");

private?JPanel?panelNorth?=?new?JPanel();

private?JPanel?panelSouth?=?new?JPanel();

private?JTextArea?area?=?new?JTextArea(6,?20);

private?JButton?btn?=?new?JButton("button");

private?JCheckBox?chk?=?new?JCheckBox("checkBox");

private?JComboBox?cmbLookAndFeel?=?new?JComboBox(new?String[]?{?"Metal",

"Widows",?"Motif",?"GTK"?});

public?LookAndFeelDemo2(String?title)?{

super(title);

Container?contentPane?=?this.getContentPane();

ButtonGroup?group?=?new?ButtonGroup();

group.add(radio1);

group.add(radio2);

group.add(radio3);

panelNorth.add(radio1);

panelNorth.add(radio2);

panelNorth.add(radio3);

panelSouth.add(btn);

panelSouth.add(chk);

panelSouth.add(cmbLookAndFeel);

contentPane.add(panelNorth,?BorderLayout.NORTH);

contentPane.add(area,?BorderLayout.CENTER);

contentPane.add(panelSouth,?BorderLayout.SOUTH);

pack();

setVisible(true);

setSize(300,?400);

this.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);

//?監(jiān)聽Item事件

radio1.addItemListener(new?MyItemListener());

radio2.addItemListener(new?MyItemListener());

radio3.addItemListener(new?MyItemListener());

}

private?class?MyItemListener?implements?ItemListener?{

public?void?itemStateChanged(ItemEvent?e)?{

//?取得點(diǎn)擊按鈕的名字

String?itemName?=?((JRadioButton)?e.getSource()).getText();

changeLookAndFeel(itemName);

}

}

//?設(shè)置外觀的private類型方法

private?void?changeLookAndFeel(String?name)?{

String?lookAndFeel?=?"";

if?(name.equals("Metal"))?{

lookAndFeel?=?"javax.swing.plaf.metal.MetalLookAndFeel";

}?else?if?(name.equals("Windows"))?{

lookAndFeel?=?"com.sun.java.swing.plaf.windows.WindowsLookAndFeel";

}?else?if?(name.equals("Motif"))?{

lookAndFeel?=?"com.sun.java.swing.plaf.motif.MotifLookAndFeel";

}else{

//取得默認(rèn)的metal外觀

lookAndFeel?=?"javax.swing.plaf.metal.MetalLookAndFeel";

}

try?{

UIManager.setLookAndFeel(lookAndFeel);

//?運(yùn)行時(shí)指定LookAndFeel，需要SwingUtilities.updateComponentTreeUI（Component

//?c)實(shí)現(xiàn)動(dòng)態(tài)的更新

SwingUtilities.updateComponentTreeUI(this);

area.setText("當(dāng)前外觀類名：\n"?+?lookAndFeel);

}?catch?(Exception?ex)?{

ex.printStackTrace();

}

}

public?static?void?main(String[]?args)?{

new?LookAndFeelDemo2("LookAndFeel");

}

}

java數(shù)據(jù)庫中跟新數(shù)據(jù)庫代碼，麻煩幫我解釋下？

public void update(String sql,String[] args)

{

try

{

con=getCon();//這里應(yīng)該在本類有一個(gè)getCon()的方法吧，用來拿到數(shù)據(jù)庫鏈接的

pstat=con.prepareStatement(sql);//創(chuàng)建一個(gè)prepareStatement，用來執(zhí)行sql語句的,pstat在成員變量里有定義吧

for(int i=0;iargs.length;i++)//這里遍歷傳進(jìn)來的args數(shù)組

{

pstat.setString(i+1, args[i]);//這里是執(zhí)行了sql語句的，把sql語句里的"?" 填充，比如那條sql的第一個(gè)問號(hào)用args[0]代替；

}

pstat.executeUpdate();//執(zhí)行更新

}catch(Exception e){e.printStackTrace();}

}

這段代碼的總體意思是傳入一條sql語句，和需要更新的內(nèi)容（在args數(shù)組里面）..

java更新數(shù)據(jù)庫表信息代碼

public static void Update(Connection con, String sql, Object... objects) {

PreparedStatement pre = null;

try {

pre = con.prepareStatement(sql);

for (int i = 0; i objects.length; i++) {

pre.setObject(i + 1, objects[i]);

}

pre.executeUpdate();

} catch (SQLException e) {

e.printStackTrace();

}

}