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java树代码 java 树型结构
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java编打出5行圣诞树，求教每一步详细思想。下面是代码
按照java树代码你java树代码的要求加详细注释的圣诞树Java程序如下：(编程思想在注释中说明)
public class ShengDanShu2 {
//这个程序的编程思想是利用对for循环变量i的控制达到一层循环代替双层循环的目的
public static void main(String[] args) {
int n=5; //初始化打印圣诞树层数变量n
int a=0; //初始化打印前置空格数变量a
int b=0; //初始化打印星号数变量b
for(int i=1;i =n;i++){ //打印n层圣诞树
if(a!=(n-i)){ //如果前置空格数不等于n-i
System.out.print(" "); //打印一个空格
a++; //前置空格数加一
i=i-1; //i变量减一 目的是固定住i变量不变直到a==n-i
}else if(b!=(2*i-1)){ //如果星号数不等于2*i-1
System.out.print("*"); //打印一个星号
b++; //星号数加一
i=i-1; //i变量减一 目的是固定住i变量不变直到b==2*i-1
}else if(a==(n-i) b==(2*i-1)){//当以上两个条件都满足时java树代码，换行初始化a和b为0
System.out.println(); //打印换行
a=0; //对新的一行重新初始化前置空格数变量a
b=0; //对新的一行重新初始化打印星号数变量b
//这里没有控制for循环的i变量减一,因为这时i变量加一,开始新一行。
}
}
}
}
运行结果：
*
***
*****
*******
*********
相关问答
Q1: java新手种树代码看不懂
import java.util.*;
class Tree { //这是一个类
int height;
Tree() { //这是类的构造方法，可以理解创建类时候的初始化
prt("Planting a seedling");
height = 0;
}
Tree(int i) { //这个也是类的构造方法带有参数而已
prt("Creating new Tree that is "
+ i + " feet tall");
height = i;
}
void info() { //这个就是类定义的方法，在主函数中可以调用
prt("Tree is " + height
+ " feet tall");
}
void info(String s) { //同上，只不过带有参数
prt(s + ": Tree is "
+ height + " feet tall");
}
void prt(String s) { //输出方法
System.out.println(s);
}
}
public class moxing2 {
public static void main(String[] args) {
for(int i = 0; i 5; i++) {
Tree t = new Tree(i); //这里就是调用的类的构造方法（带有参数的那个）
t.info();
t.info("overloaded method");
}
// Overloaded constructor:
new Tree();
}
}
Q2: 求java树形目录代码范例
给你一个。一共三个类。是个资源管理器的代码
// FileList.java
package tl.exercise.swing;
import java.awt.Color;
import java.awt.Component;
import javax.swing.JLabel;
import javax.swing.JList;
import javax.swing.ListCellRenderer;
import javax.swing.ListModel;
import javax.swing.event.ListDataListener;
public class FileList
extends JList {
// PathNode theNode;
FileListModel dataModel;
static final long serialVersionUID = 10;
public FileList() {
dataModel = new FileListModel();
setModel(dataModel);
this.setCellRenderer(new MyCellRenderer());
}
public void fireTreeSelectionChanged(I_fileSystem node) {
// Vector files = node.getFiles();
// theNode = node;
dataModel.setNode(node);
updateUI();
}
}
class FileListModel implements ListModel {
FileList theList;
I_fileSystem node;
char fileType = I_fileSystem.ALL;
public void setNode(I_fileSystem node) {
this.node = node;
}
public Object getElementAt(int index) {
if (node != null) {
return ((I_fileSystem) node).getChild(fileType, index);
} else {
return null;
}
}
public int getSize() {
if (node != null) {
return ((I_fileSystem) node).getChildCount(fileType);
} else {
return 0;
}
}
public void addListDataListener(ListDataListener l) {
}
public void removeListDataListener(ListDataListener l) {
}
}
class MyCellRenderer extends JLabel implements ListCellRenderer {
public MyCellRenderer() {
setOpaque(true);
}
public Component getListCellRendererComponent(
JList list,
Object value,
int index,
boolean isSelected,
boolean cellHasFocus)
{
FolderNode node = (FolderNode) value;
setIcon(node.getIcon());
setText(value.toString());
setBackground(isSelected ? Color.BLUE.darker().darker() : Color.WHITE);
setForeground(isSelected ? Color.WHITE : Color.BLACK);
return this;
}
}
package tl.exercise.swing;
//JExplorer.java
import java.awt.BorderLayout;
import java.awt.Dimension;
import java.awt.Toolkit;
import javax.swing.JFrame;
import javax.swing.JPanel;
import javax.swing.JScrollPane;
import javax.swing.JSplitPane;
import javax.swing.border.BevelBorder;
public class JExplorer {
public static void main(String[] args) {
// JFrame.setDefaultLookAndFeelDecorated(true);
JFrame frame = new JFrame();
frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
frame.getContentPane().add(new UI(frame));
frame.pack();
Dimension screen = Toolkit.getDefaultToolkit().getScreenSize();
int left = (screen.width - frame.getWidth()) / 2;
int top = (screen.height - frame.getHeight()) / 2;
frame.setLocation(left, top);
frame.setVisible(true);
}
}
class UI extends JPanel {
// implements I_menuHandler{
static final long serialVersionUID = 0l;
static int LEFT_WIDTH = 200;
static int RIGHT_WIDTH = 300;
static int WINDOW_HEIGHT = 300;
JFrame frame = null;
public UI(JFrame frame) {
// EmptyBorder eb = new EmptyBorder(1,1,1,1);
this.frame = frame;
setPreferredSize(new Dimension(800, 600));
setBorder(new BevelBorder(BevelBorder.LOWERED));
setLayout(new BorderLayout());
FileList list = new FileList();
FileTree tree = new FileTree(list);
tree.setDoubleBuffered(true);
list.setDoubleBuffered(true);
JScrollPane treeView = new JScrollPane(tree);
treeView.setPreferredSize(
new Dimension(LEFT_WIDTH, WINDOW_HEIGHT));
JScrollPane listView = new JScrollPane(list);
listView.setPreferredSize(
new Dimension(RIGHT_WIDTH, WINDOW_HEIGHT));
JSplitPane pane =
new JSplitPane(JSplitPane.HORIZONTAL_SPLIT, treeView,
listView);
pane.setDividerLocation(300);
pane.setDividerSize(4);
// pane.setDoubleBuffered(true);
add(pane);
}
}
package tl.exercise.swing;
//FileTree.java
/***********************************************************
* Author: Jason
* email: tl21cen@hotmail.com
* CSDN blog:
***********************************************************/
import java.awt.Component;
import java.io.File;
import java.util.Vector;
import javax.swing.Icon;
import javax.swing.JTree;
import javax.swing.event.TreeExpansionEvent;
import javax.swing.event.TreeExpansionListener;
import javax.swing.event.TreeModelListener;
import javax.swing.event.TreeSelectionEvent;
import javax.swing.event.TreeSelectionListener;
import javax.swing.filechooser.FileSystemView;
import javax.swing.tree.DefaultTreeCellRenderer;
import javax.swing.tree.TreeModel;
import javax.swing.tree.TreePath;
public class FileTree extends JTree {
static final long serialVersionUID = 0;
private FileList theList;
public FileTree(FileList list) {
theList = list;
setModel(new FileSystemModel(new FolderNode()));
this.setCellRenderer(new FolderRenderer());
addTreeSelectionListener(new TreeSelectionListener() {
public void valueChanged(TreeSelectionEvent tse) {
}
});
this.setSelectionRow(0);
}
public void fireValueChanged(TreeSelectionEvent tse) {
TreePath tp = tse.getNewLeadSelectionPath();
Object o = tp.getLastPathComponent();
// theList.fireTreeSelectionChanged((PathNode)o);
theList.fireTreeSelectionChanged((FolderNode) o);
}
public void fireTreeCollapsed(TreePath path) {
super.fireTreeCollapsed(path);
TreePath curpath = getSelectionPath();
if (path.isDescendant(curpath)) {
setSelectionPath(path);
}
}
public void fireTreeWillExpand(TreePath path) {
System.out.println("Path will expand is " + path);
}
public void fireTreeWillCollapse(TreePath path) {
System.out.println("Path will collapse is " + path);
}
class ExpansionListener implements TreeExpansionListener {
FileTree tree;
public ExpansionListener(FileTree ft) {
tree = ft;
}
public void treeCollapsed(TreeExpansionEvent tee) {
}
public void treeExpanded(TreeExpansionEvent tee) {
}
}
}
class FileSystemModel implements TreeModel {
I_fileSystem theRoot;
char fileType = I_fileSystem.DIRECTORY;
public FileSystemModel(I_fileSystem fs) {
theRoot = fs;
}
public Object getRoot() {
return theRoot;
}
public Object getChild(Object parent, int index) {
return ((I_fileSystem) parent).getChild(fileType, index);
}
public int getChildCount(Object parent) {
return ((I_fileSystem) parent).getChildCount(fileType);
}
public boolean isLeaf(Object node) {
return ((I_fileSystem) node).isLeaf(fileType);
}
public int getIndexOfChild(Object parent, Object child) {
return ((I_fileSystem) parent).getIndexOfChild(fileType, child);
}
public void valueForPathChanged(TreePath path, Object newValue) {
}
public void addTreeModelListener(TreeModelListener l) {
}
public void removeTreeModelListener(TreeModelListener l) {
}
}
interface I_fileSystem {
final public static char DIRECTORY = 'D';
final public static char FILE = 'F';
final public static char ALL = 'A';
public Icon getIcon();
public I_fileSystem getChild(char fileType, int index);
public int getChildCount(char fileType);
public boolean isLeaf(char fileType);
public int getIndexOfChild(char fileType, Object child);
}
/**
* A data model for a JTree. This model explorer windows file system directly.
*
* p
* Perhaps there is a fatal bug with this design. For speed, each of instances
* of this model contains file objects of subdirectory, up to now, there isn't
* any method to release them until program be end. I'm afraid that the memory
* would be full of if the file system is large enough and JVM memery size
* setted too small.
*
* p
* I won't pay more attention to solve it. it isn't goal of current a exercise.
*
* @author Jason
*/
class FolderNode implements I_fileSystem {
// private static FolderNode theRoot;
private static FileSystemView fsView;
private static boolean showHiden = true;;
private File theFile;
private VectorFile all = new VectorFile();
private VectorFile folder = new VectorFile();
/**
* set that whether apply hiden file.
*
* @param ifshow
*/
public void setShowHiden(boolean ifshow) {
showHiden = ifshow;
}
public Icon getIcon() {
return fsView.getSystemIcon(theFile);
}
public String toString() {
// return fsView.
return fsView.getSystemDisplayName(theFile);
}
/**
* create a root node. by default, it should be the DeskTop in window file
* system.
*
*/
public FolderNode() {
fsView = FileSystemView.getFileSystemView();
theFile = fsView.getHomeDirectory();
prepareChildren();
}
private void prepareChildren() {
File[] files = fsView.getFiles(theFile, showHiden);
for (int i = 0; i files.length; i++) {
all.add(files[i]);
if (files[i].isDirectory()
!files[i].toString().toLowerCase().endsWith(".lnk")) {
folder.add(files[i]);
}
}
}
private FolderNode(File file) {
theFile = file;
prepareChildren();
}
public FolderNode getChild(char fileType, int index) {
if (I_fileSystem.DIRECTORY == fileType) {
return new FolderNode(folder.get(index));
} else if (I_fileSystem.ALL == fileType) {
return new FolderNode(all.get(index));
} else if (I_fileSystem.FILE == fileType) {
return null;
} else {
return null;
}
}
public int getChildCount(char fileType) {
if (I_fileSystem.DIRECTORY == fileType) {
return folder.size();
} else if (I_fileSystem.ALL == fileType) {
return all.size();
} else if (I_fileSystem.FILE == fileType) {
return -1;
} else {
return -1;
}
}
public boolean isLeaf(char fileType) {
if (I_fileSystem.DIRECTORY == fileType) {
return folder.size() == 0;
} else if (I_fileSystem.ALL == fileType) {
return all.size() == 0;
} else if (I_fileSystem.FILE == fileType) {
return true;
} else {
return true;
}
}
public int getIndexOfChild(char fileType, Object child) {
if (child instanceof FolderNode) {
if (I_fileSystem.DIRECTORY == fileType) {
return folder.indexOf(((FolderNode) child).theFile);
} else if (I_fileSystem.ALL == fileType) {
return all.indexOf(((FolderNode) child).theFile);
} else if (I_fileSystem.FILE == fileType) {
return -1;
} else {
return -1;
}
} else {
return -1;
}
}
}
class FolderRenderer extends DefaultTreeCellRenderer {
private static final long serialVersionUID = 1L;
public Component getTreeCellRendererComponent(JTree tree, Object value,
boolean sel, boolean expanded, boolean leaf, int row,
boolean hasFocus) {
I_fileSystem node = (I_fileSystem) value;
Icon icon = node.getIcon();
setLeafIcon(icon);
setOpenIcon(icon);
setClosedIcon(icon);
return super.getTreeCellRendererComponent(tree, value, sel, expanded,
leaf, row, hasFocus);
}
}
Q3: 用JAVA语言编写一个种树的项目
public class Tree {
private int treeId;
private String treeType;// 树种类型
private int count; //种植数量
public int getCount() {
return count;
}
public void setCount(int count) {
this.count = count;
}
public int getTreeId() {
return treeId;
}
public void setTreeId(int treeId) {
this.treeId = treeId;
}
public String getTreeType() {
return treeType;
}
public void setTreeType(String treeType) {
this.treeType = treeType;
}
}
public class Address {
private int addCode;//地区编码
private String area;//地名
public int getAddCode() {
return addCode;
}
public void setAddCode(int addCode) {
this.addCode = addCode;
}
public String getArea() {
return area;
}
public void setArea(String area) {
this.area = area;
}
}
import java.util.HashMap;
import java.util.Map;
public class People {
private int userId;
private String username;
private MapString,MapString,Integer map;
/**
* 传入地区和树种，种树成功。保存到map中。
* @param address
* @param tree
*/
public void plantingTrees(String address,Tree tree){
Map map = new HashMap();
map.put(tree.getTreeType(),tree.getCount());
this.map.put(address,map);
}
public int getUserId() {
return userId;
}
public void setUserId(int userId) {
this.userId = userId;
}
public String getUsername() {
return username;
}
public void setUsername(String username) {
this.username = username;
}
public MapString, MapString, Integer getMap() {
return map;
}
public void setMap(MapString, MapString, Integer map) {
this.map = map;
}
}
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