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java代码及实现功能 java代码示例
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java编程，实现以下功能
代码如下java代码及实现功能：
public class App {
public static void main(String[] args) {
String name = "My name is Networkcrazy";
System.out.println("字符串java代码及实现功能的长度java代码及实现功能：" + name.length());
System.out.println("字符串中的第一个字符java代码及实现功能：" + name.charAt(0));
System.out.println("字符串中的最后一个字符java代码及实现功能：" + name.charAt(name.length() - 1));
System.out.println("字符串中的第一个单词：" + name.split(" ")[0]);
System.out.println("字符串中crazy的位置：" + name.indexOf("crazy"));
}
}
运行结果：
相关问答
Q1: 请用java代码实现如下方法
//供参考，代码应该没问题，难点主要是在如何匹配连续字符串，这点有小技巧
public class TestBaiduKnow {
public static void main(String args[]) throws Exception {
String s = "Sdabcdk3abcdabcdgg3abcdabcdabcd55fg";
char[] in = s.toCharArray();
char[] out = "abcd".toCharArray();
int cnt = 0;
cnt = maxfleg(in, out);
System.out.println("出现次数： " + cnt);
}
private static int maxfleg(char[] inputstr, char[] outputstr) {
String s = "";
String s2 = "";
for (int i = 0; i outputstr.length; i++)
s2 += outputstr[i];
int cnt = 0;
int maxcnt = 0;
for (int i = 0; i inputstr.length - 4; i++) {
for (int j = i; j i + 4; j++)
s += inputstr[j];
if (s.equals(s2)) {
cnt += 1;
i += 3;
if (cnt maxcnt)
maxcnt = cnt;
} else
cnt = 0;
s = "";
}
return maxcnt;
}
}
Q2: java是实现什么功能
Java是Sun公司推出的一种编程语言。它是一种通过解释方式来执行的语言，语法规则和C++类似。同时，Java也是一种跨平台的程序设计语言。用Java语言编写的程序叫做“Applet”(小应用程序)，用编译器将它编译成类文件后，将它存在WWW页面中，并在HTML档上作好相应标记，用户端只要装上Java的客户软件就可以在网上直接运行“Applet”。 Java非常适合于企业网络和Internet环境，现在已成为Internet中最受欢迎、最有影响的编程语言之一。 Java有许多值得称道的优点，如简单、面向对象、分布式、解释性、可靠、安全、结构中立性、可移植性、高性能、多线程、动态性等。Java摈弃了C++中各种弊大于利的功能和许多很少用到的功能。 Jave可以运行与任何微处理器，用Java开发的程序可以在网络上传输，并运行于任何客户机上。
Q3: 利用java编写代码实现如下功能，需要全部代码
很简单的应用java代码及实现功能，为了节省字数java代码及实现功能，代码注释我就不加了
首先是显示层，LoinWindow：
import java.awt.FlowLayout;
import java.awt.GridBagConstraints;
import java.awt.GridBagLayout;
import java.awt.GridLayout;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;
import java.awt.event.FocusEvent;
import java.awt.event.FocusListener;
import javax.swing.JButton;
import javax.swing.JFrame;
import javax.swing.JLabel;
import javax.swing.JOptionPane;
import javax.swing.JPanel;
import javax.swing.JTextField;
import javax.swing.border.EmptyBorder;
public class LoinWindow extends JFrame implements ActionListener, FocusListener {
private JPanel mainPanel, namePanel, btnPanel;
private JTextField tfName, tfPsd;
private JButton btnLogin, btnCancel;
private static final int WIDTH = 300;
private static final int HEIGHT = 200;
private LoginService service = new LoginService();
public LoinWindow() {
super("登录窗体");
}
public void launch() {
setSize(WIDTH, HEIGHT);
setVisible(true);
setDefaultCloseOperation(EXIT_ON_CLOSE);
GridLayout mainLayout = new GridLayout(2, 1);
mainLayout.setVgap(10);
mainPanel = new JPanel(mainLayout);
GridBagLayout nameLayout = new GridBagLayout();
namePanel = new JPanel(nameLayout);
namePanel.setBorder(new EmptyBorder(10, 10, 10, 10));
JLabel nameLabel = new JLabel("姓名：");
tfName = new JTextField();
JLabel psdLabel = new JLabel("密码：");
tfPsd = new JTextField();
JLabel blank = new JLabel(" ");
namePanel.add(nameLabel);
namePanel.add(tfName);
namePanel.add(blank);
namePanel.add(psdLabel);
namePanel.add(tfPsd);
GridBagConstraints s = new GridBagConstraints();
s.fill = GridBagConstraints.BOTH;
s.gridwidth = 1;
s.weightx = 0;
s.weighty = 0;
nameLayout.setConstraints(nameLabel, s);
s.gridwidth = 0;
s.weightx = 1;
s.weighty = 0;
nameLayout.setConstraints(tfName, s);
s.gridwidth = 0;
s.weightx = 4;
s.weighty = 0;
nameLayout.setConstraints(blank, s);
s.gridwidth = 1;
s.weightx = 0;
s.weighty = 0;
nameLayout.setConstraints(psdLabel, s);
s.gridwidth = 3;
s.weightx = 1;
s.weighty = 0;
nameLayout.setConstraints(tfPsd, s);
FlowLayout btnLayout = new FlowLayout();
btnLayout.setAlignment(FlowLayout.CENTER);
btnPanel = new JPanel(btnLayout);
btnLogin = new JButton("确定");
btnCancel = new JButton("取消");
btnPanel.add(btnLogin);
btnPanel.add(btnCancel);
btnCancel.addActionListener(this);
btnLogin.addActionListener(this);
mainPanel.add(namePanel);
mainPanel.add(btnPanel);
setContentPane(mainPanel);
tfName.addFocusListener(this);
tfPsd.addFocusListener(this);
pack();
setSize(WIDTH, HEIGHT);
setLocationRelativeTo(null);
}
@Override
public void actionPerformed(ActionEvent e) {
Object source = e.getSource();
if(source == btnCancel) {
System.exit(0);
} else if(source == btnLogin) {
String username = tfName.getText();
String password = tfPsd.getText();
boolean success = service.login(username, password);
if(success) {
warn("成功", "登录成功！");
} else {
warn("失败", "您输入的用户名或密码错误 ！");
}
}
}
@Override
public void focusGained(FocusEvent arg0) {
}
@Override
public void focusLost(FocusEvent e) {
Object source = e.getSource();
if(source == tfName) {
String username = tfName.getText();
try {
service.matchUsername(username);
} catch (LoginException e1) {
warn("验证错误", e1.getMessage());
}
} else if(source == tfPsd) {
String password = tfPsd.getText();
try {
service.matchPassword(password);
} catch (LoginException e1) {
warn("验证错误", e1.getMessage());
}
}
}
private void warn(String title, String msg) {
JOptionPane.showMessageDialog(null, msg, title, JOptionPane.INFORMATION_MESSAGE);
}
public static void main(String[] args) {
new LoinWindow().launch();
}
}
然后是模型层：LoginDao
public class LoginDao {
public boolean login(String username, String password) {
if(username.equals("admin") password.equals("12345")) {
return true;
}
return false;
}
}
LoginService
import java.util.regex.Pattern;
public class LoginService {
private static final Pattern LOGIN_PATTERN = Pattern.compile("[a-zA-Z]+");
private static final Pattern PASSWORD_PATTERN = Pattern.compile("[1-9]+");
private LoginDao dao = new LoginDao();
public boolean matchUsername(String username) throws LoginException {
if(null == username || username.isEmpty()) {
return false;
}
if(!LOGIN_PATTERN.matcher(username).matches()) {
throw new LoginException("您输入的用户名不合法，请输入英文！");
}
return true;
}
public boolean matchPassword(String password) throws LoginException {
if(null == password || password.isEmpty()) {
return false;
}
if(!PASSWORD_PATTERN.matcher(password).matches()) {
throw new LoginException("您输入的密码不合法，请输入数字！");
}
return true;
}
public boolean login(String username, String password) {
if(null == username || username.isEmpty()) {
return false;
}
if(null == password || password.isEmpty()) {
return false;
}
if(!dao.login(username, password)) {
return false;
}
return true;
}
}
LoginException
public class LoginException extends Exception {
public LoginException(String arg0) {
super(arg0);
}
}
不知道分层设计思想是不是我想的这样
Q4: 利用java编程编写代码，实现如下功能：
package example;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;
import javax.swing.JFrame;
import javax.swing.JMenu;
import javax.swing.JMenuBar;
import javax.swing.JMenuItem;
import javax.swing.JOptionPane;
import javax.swing.JPanel;
import javax.swing.border.EmptyBorder;
public class demo extends JFrame{
private JMenuBar menu = new JMenuBar();
private JPanel contentPane = new JPanel();
public demo()
{
setTitle("compiler");
setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
setJMenuBar(menu);
//JMenu correct = new JMenu("正确用例");
//JMenu wrong = new JMenu("错误用例");
////JMenuItem WP = wrong.add("语法错误");
//JMenuItem WL = wrong.add("词法错误");
JMenu edit = new JMenu("编辑");
JMenu help = new JMenu("帮助");
JMenu document = new JMenu("文件");
JMenuItem copy = edit.add("复制");
JMenu color = new JMenu("颜色");
JMenuItem p = color.add("前景色");
p.addActionListener(new ActionListener()
{
@Override
public void actionPerformed(ActionEvent e) {
JOptionPane.showMessageDialog(null,
"该项目正在建设中", "信息",
JOptionPane.INFORMATION_MESSAGE);
}
});
JMenuItem b = color.add("背景色");
b.addActionListener(new ActionListener()
{
@Override
public void actionPerformed(ActionEvent e) {
JOptionPane.showMessageDialog(null,
"该项目正在建设中", "信息",
JOptionPane.INFORMATION_MESSAGE);
}
});
edit.add(color);
JMenuItem select = edit.add("全选");
menu.add(document);
menu.add(edit);
menu.add(help);
setLocation(400,200);
setSize(300, 300);
contentPane.setBorder(new EmptyBorder(5, 5, 5, 5));
setContentPane(contentPane);
}
public static void main(String[]args)
{
demo browser = new demo();
browser.setVisible(true);
}
}
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