java編打出5行圣誕樹，求教每一步詳細(xì)思想。下面是代碼

按照你的要求加詳細(xì)注釋的圣誕樹Java程序如下：(編程思想在注釋中說明)

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public?class?ShengDanShu2?{

//這個(gè)程序的編程思想是利用對(duì)for循環(huán)變量i的控制達(dá)到一層循環(huán)代替雙層循環(huán)的目的

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

int???n=5;???//初始化打印圣誕樹層數(shù)變量n

int???a=0;???//初始化打印前置空格數(shù)變量a

int???b=0;???//初始化打印星號(hào)數(shù)變量b

for(int?i=1;i?=n;i++){???//打印n層圣誕樹

if(a!=(n-i)){????//如果前置空格數(shù)不等于n-i

System.out.print("?");?//打印一個(gè)空格

a++;????//前置空格數(shù)加一???

i=i-1;????//i變量減一??目的是固定住i變量不變直到a==n-i

}else?if(b!=(2*i-1)){???//如果星號(hào)數(shù)不等于2*i-1

System.out.print("*");??//打印一個(gè)星號(hào)

b++;????//星號(hào)數(shù)加一

i=i-1;???//i變量減一??目的是固定住i變量不變直到b==2*i-1

}else?if(a==(n-i)??b==(2*i-1)){//當(dāng)以上兩個(gè)條件都滿足時(shí)，換行初始化a和b為0???

System.out.println();??//打印換行?

a=0;???//對(duì)新的一行重新初始化前置空格數(shù)變量a

b=0;??//對(duì)新的一行重新初始化打印星號(hào)數(shù)變量b

//這里沒有控制for循環(huán)的i變量減一,因?yàn)檫@時(shí)i變量加一,開始新一行。

}???

}???

}?????

}

運(yùn)行結(jié)果：

*

***

*****

*******

*********

哪位大俠可以幫我寫一段java代碼！是關(guān)于根據(jù)數(shù)據(jù)庫里的數(shù)據(jù)來形成一個(gè)動(dòng)態(tài)樹形圖

這是代碼，你可以自己調(diào)試一下。

數(shù)據(jù)結(jié)構(gòu)如下：

CREATE TABLE dtree (

id int,

pid int,

name varchar(200),

url varchar(200),

title varchar(200),

target varchar(200),

icon varchar(200),

iconopen varchar(200),

opened bit);

為了實(shí)現(xiàn)獲取數(shù)據(jù)庫變量功能，需要建立一個(gè)DTree類，并編譯生成CLASS文件，放入\WEB-INF\classes文件夾下。

DTree類代碼如下：

package work3;

public class DTree {

private int id;

private int pid;

private String name;

private String url;

private String title;

private String target;

private String icon;

private String iconOpen;

private int opened;

public int getId() {

return id;

}

public void setId(int id) {

this.id = id;

}

public int getPid() {

return pid;

}

public void setPid(int pid) {

this.pid = pid;

}

public String getName() {

return name;

}

public void setName(String name) {

this.name = name;

}

public String getUrl() {

return url;

}

public void setUrl(String url) {

this.url = url;

}

public String getTitle() {

return title;

}

public void setTitle(String title) {

this.title = title;

}

public String getTarget() {

return target;

}

public void setTarget(String target) {

this.target = target;

}

public String getIcon() {

return icon;

}

public void setIcon(String icon) {

this.icon = icon;

}

public String getIconOpen() {

return iconOpen;

}

public void setIconOpen(String iconOpen) {

this.iconOpen = iconOpen;

}

public int getOpened() {

return opened;

}

public void setOpened(int opened) {

this.opened = opened;

}

}

work3.jsp代碼如下：

%@ page language="java" contentType="text/html; charset=GB18030" pageEncoding="GB18030"%

%@ page import="java.sql.*"%

jsp:useBean id='settree' scope="application" class="work3.DTree" /

!DOCTYPE html PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN"

""

html

head

meta http-equiv="Content-Type" content="text/html; charset=GB18030"

link rel="StyleSheet" href="dtree.css" type="text/css" /

script type="text/javascript" src="dtree.js"/script

titledTree in MySQL/title

/head

body

h2

Example

/h2

div class="dtree"

p

a href="javascript: d.openAll();"open all/a |

a href="javascript: d.closeAll();"close all/a

/p

script type="text/javascript"

!--

d = new dTree('d');

%

//驅(qū)動(dòng)程序名

String driverName = "com.microsoft.jdbc.sqlserver.SQLServerDriver";

//數(shù)據(jù)庫用戶名

String userName = "sa";

//密碼

String userPwd = "1";

//數(shù)據(jù)庫名

String dbName = "master";

//表名

String tableName = "dtree";

//連接字符串

String url="jdbc:microsoft:sqlserver://localhost:1433;DatabaseName="+dbName;

//加載驅(qū)動(dòng)

Class.forName(driverName).newInstance();

//連接數(shù)據(jù)庫

java.sql.Connection conn = DriverManager.getConnection(url,userName,userPwd);

//得到Statement實(shí)例

java.sql.Statement statement = conn.createStatement();

//查詢數(shù)據(jù)

String sql = "select * from " + tableName;

//返回結(jié)果

java.sql.ResultSet rs = statement.executeQuery(sql);

//獲取變量

while (rs.next()) {

settree.setId(rs.getInt(1));

settree.setPid(rs.getInt(2));

settree.setName(rs.getString(3));

settree.setUrl(rs.getString(4));

settree.setTitle(rs.getString(5));

settree.setTarget(rs.getString(6));

settree.setIcon(rs.getString(7));

settree.setIconOpen(rs.getString(8));

settree.setOpened(rs.getInt(9));

if(settree.getPid()==0)

settree.setOpened(1);

%

d.add(%=settree.getId()%,%=settree.getPid()%,'%=settree.getName()%','%=settree.getUrl()%','%=settree.getTitle()%','%=settree.getTarget()%','','',%=settree.getOpened()%);

%

}

%

document.write(d);

//--

/script

/div

/body

/html

求助用JAVA打印一個(gè)圣誕樹

朋友 你說的最好一句話我沒明白？

你能具體說下嗎？最好弄個(gè)圖片。

我跟你說一下思路：就是用for循環(huán)就可以.

---給你答案 供你參考，倉促寫的：

public class ChristmasTree {

int x = 2;

int i = 0;

public void tree() {

for(i=0; i3; i++) {

for(int j=x; j=0; j--) {

System.out.print(" ");

}

x--;

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

System.out.print("*"+" ");

}

System.out.println();

}

}

public static void main(String args[]) {

new ChristmasTree().tree();

}

}