怎么用java編寫如下程序在屏幕上輸出如下圖形 * *** ***** ******* ***** *** * 循環(huán)語句做（if語句）

這個圖形對吧？

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你確定不是 for/while/do-while loop？if 不是循環(huán)語句吧

用for loop做的：

public class NestedLoop{

public static void main (String[] args){

for (int i=0; i7; i++){

if (i %2 == 0){

for (int s=0; s(7-i-1)/2; s++){

System.out.print(" ");

}

for (int d=0; di +1; d++){

System.out.print("*");

}

System.out.println();

}

}

for (int i=5; i-1; i--){

if (i %2 == 0){

for (int s=0; s(7-i-1)/2; s++){

System.out.print(" ");

}

for (int d=0; di+1; d++){

System.out.print("*");

}

System.out.println();

}

}

}

}

給點分唄？我時差黨，大半夜12點多跟這給你做題~ ^ ^

java如何實現(xiàn)屏幕錄制功能?

這種功能一本不用JAVA寫，因為他要和系統(tǒng)的本地資源打交道。

你可以使用VC、VB、delphi這類原生開發(fā)工具做。

也可以使用C#來寫。

能用java代碼打開一個應(yīng)用程序嗎？

可以，java功能可是相當(dāng)強大的。

這個是調(diào)用應(yīng)用程序的代碼：

Runtime ec;

ec=Runtime.getRuntime();

ec.exec("這里是應(yīng)用程序的路徑或者命令");

比如：ec.exec("c:\\123.exe");

利用java編寫代碼實現(xiàn)如下功能，需要全部代碼

很簡單的應(yīng)用，為了節(jié)省字?jǐn)?shù)，代碼注釋我就不加了

首先是顯示層，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("登錄窗體");

}

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("密碼：");

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("確定");

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",?"登錄成功！");

}?else?{

warn("失敗",?"您輸入的用戶名或密碼錯誤?！");

}

}

}

@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("驗證錯誤",?e1.getMessage());

}

}?else?if(source?==?tfPsd)?{

String?password?=?tfPsd.getText();

try?{

service.matchPassword(password);

}?catch?(LoginException?e1)?{

warn("驗證錯誤",?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();

}

}

然后是模型層：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("您輸入的用戶名不合法，請輸入英文！");

}

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("您輸入的密碼不合法，請輸入數(shù)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);

}

}

不知道分層設(shè)計思想是不是我想的這樣

用java實現(xiàn)錄像機功能

底層的我不會,不知調(diào)用那個工具包,看樓下的啦. 樓下的,好象可以通過虛擬機調(diào)用win32 API的啦,樓下去翻翻資料.