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新手学java用什么软件好?java中map集合怎么遍历

admin admin 发表于2022-05-13 07:39:23 浏览110 评论0

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新手学java用什么软件好

推荐使用eclipse,eclipse是专精于JAVA开发(还支持其他语言的开发,不过JAVA开发的功能最完善)的IDE(集成开发环境),因为刚开始其设计就是为了用于JAVA的开发。并且eclipse是开源的软件,可扩展性也很好。

eclipse在其官网上可以免费下载,因为国外的不能直接下载,需要选择国内的镜像下载。怕你找不到镜像在哪,我直接把官方的镜像路径发上来(这是在中科大的镜像)网页链接

如果能帮到你,请采纳,谢谢

java中map集合怎么遍历

遍历方法代码如下:

import java.util.HashMap;import java.util.Map;public class App01 {	public static void main(String args) {				Map《String, String》 map1 = new HashMap《String, String》();		map1.put(“A“, “ABC“);		map1.put(“B“, “BCD“);		map1.put(“C“, “CDE“);		// 遍历		for(Map.Entry《String, String》 entry : map1.entrySet()) {			System.out.println(entry.getKey() + “-》“ + entry.getValue());		}	}}

java 俄罗斯方块

import java.awt.*;import java.awt.event.*;//俄罗斯方块类public class Mytest extends Frame{ public static boolean isPlay=false; public static int level=1,score=0; public static TextField scoreField,levelField; public static MyTimer timer; GameCanvas gameScr; public static void main(String argus){ Mytest ers = new Mytest(“俄罗斯方块游戏“); WindowListener win_listener = new WinListener(); ers.addWindowListener(win_listener); }// 俄罗斯方块类的构造方法 Mytest(String title){ super(title); setSize(600,480); setLayout(new GridLayout(1,2)); gameScr = new GameCanvas(); gameScr.addKeyListener(gameScr); timer = new MyTimer(gameScr); timer.setDaemon(true); timer.start(); timer.suspend(); add(gameScr); Panel rightScr = new Panel(); rightScr.setLayout(new GridLayout(2,1,0,30)); rightScr.setSize(120,500); add(rightScr);// 右边信息窗体的布局 MyPanel infoScr = new MyPanel(); infoScr.setLayout(new GridLayout(4,1,0,5)); infoScr.setSize(120,300); rightScr.add(infoScr);// 定义标签和初始值 Label scorep = new Label(“分数:“,Label.LEFT); Label levelp = new Label(“级数:“,Label.LEFT); scoreField = new TextField(8); levelField = new TextField(8); scoreField.setEditable(false); levelField.setEditable(false); infoScr.add(scorep); infoScr.add(scoreField); infoScr.add(levelp); infoScr.add(levelField); scorep.setSize(new Dimension(20,60)); scoreField.setSize(new Dimension(20,60)); levelp.setSize(new Dimension(20,60)); levelField.setSize(new Dimension(20,60)); scoreField.setText(“0“); levelField.setText(“1“);// 右边控制按钮窗体的布局 MyPanel controlScr = new MyPanel(); controlScr.setLayout(new GridLayout(5,1,0,5)); rightScr.add(controlScr);// 定义按钮play Button play_b = new Button(“开始游戏“); play_b.setSize(new Dimension(50,200)); play_b.addActionListener(new Command(Command.button_play,gameScr));// 定义按钮Level UP Button level_up_b = new Button(“提高级数“); level_up_b.setSize(new Dimension(50,200)); level_up_b.addActionListener(new Command(Command.button_levelup,gameScr));// 定义按钮Level Down Button level_down_b =new Button(“降低级数“); level_down_b.setSize(new Dimension(50,200)); level_down_b.addActionListener(new Command(Command.button_leveldown,gameScr));// 定义按钮Level Pause Button pause_b =new Button(“游戏暂停“); pause_b.setSize(new Dimension(50,200)); pause_b.addActionListener(new Command(Command.button_pause,gameScr));// 定义按钮Quit Button quit_b = new Button(“退出游戏“); quit_b.setSize(new Dimension(50,200)); quit_b.addActionListener(new Command(Command.button_quit,gameScr)); controlScr.add(play_b); controlScr.add(level_up_b); controlScr.add(level_down_b); controlScr.add(pause_b); controlScr.add(quit_b); setVisible(true); gameScr.requestFocus(); }}//重写MyPanel类,使Panel的四周留空间class MyPanel extends Panel{ public Insets getInsets(){ return new Insets(30,50,30,50); }}//游戏画布类class GameCanvas extends Canvas implements KeyListener{ final int unitSize = 30; //小方块边长 int rowNum; //正方格的行数 int columnNum; //正方格的列数 int maxAllowRowNum; //允许有多少行未削 int blockInitRow; //新出现块的起始行坐标 int blockInitCol; //新出现块的起始列坐标 int scrArr; //屏幕数组 Block b; //对方快的引用// 画布类的构造方法 GameCanvas(){ rowNum = 15; columnNum = 10; maxAllowRowNum = rowNum - 2; b = new Block(this); blockInitRow = rowNum - 1; blockInitCol = columnNum/2 - 2; scrArr = new int ; }// 初始化屏幕,并将屏幕数组清零的方法 void initScr(){ for(int i=0;i《rowNum;i++) for (int j=0; j《columnNum;j++) scrArr[i][j]=0; b.reset(); repaint(); }// 重新刷新画布方法 public void paint(Graphics g){ for(int i = 0; i 《 rowNum; i++) for(int j = 0; j 《 columnNum; j++) drawUnit(i,j,scrArr[i][j]); }// 画方块的方法 public void drawUnit(int row,int col,int type){ scrArr[row][col] = type; Graphics g = getGraphics(); switch(type){ //表示画方快的方法 case 0: g.setColor(Color.black);break; //以背景为颜色画 case 1: g.setColor(Color.blue);break; //画正在下落的方块 case 2: g.setColor(Color.magenta);break; //画已经落下的方法 } g.fill3DRect(col*unitSize,getSize().height-(row+1)*unitSize,unitSize,unitSize,true); g.dispose(); } public Block getBlock(){ return b; //返回block实例的引用 }// 返回屏幕数组中(row,col)位置的属性值 public int getScrArrXY(int row,int col){ if (row 《 0 || row 》= rowNum || col 《 0 || col 》= columnNum) return(-1); else return(scrArr[row][col]); }// 返回新块的初始行坐标方法 public int getInitRow(){ return(blockInitRow); //返回新块的初始行坐标 }// 返回新块的初始列坐标方法 public int getInitCol(){ return(blockInitCol); //返回新块的初始列坐标 }// 满行删除方法 void deleteFullLine(){ int full_line_num = 0; int k = 0; for (int i=0;i《rowNum;i++){ boolean isfull = true; L1:for(int j=0;j《columnNum;j++) if(scrArr[i][j] == 0){ k++; isfull = false; break L1; } if(isfull) full_line_num++; if(k!=0 && k-1!=i && !isfull) for(int j = 0; j 《 columnNum; j++){ if (scrArr[i][j] == 0) drawUnit(k-1,j,0); else drawUnit(k-1,j,2); scrArr[k-1][j] = scrArr[i][j]; } } for(int i = k-1 ;i 《 rowNum; i++){ for(int j = 0; j 《 columnNum; j++){ drawUnit(i,j,0); scrArr[i][j]=0; } } Mytest.score += full_line_num; Mytest.scoreField.setText(““+Mytest.score); }// 判断游戏是否结束方法 boolean isGameEnd(){ for (int col = 0 ; col 《columnNum; col ++){ if(scrArr[maxAllowRowNum][col] !=0) return true; } return false; } public void keyTyped(KeyEvent e){ } public void keyReleased(KeyEvent e){ }// 处理键盘输入的方法 public void keyPressed(KeyEvent e){ if(!Mytest.isPlay) return; switch(e.getKeyCode()){ case KeyEvent.VK_DOWN:b.fallDown();break; case KeyEvent.VK_LEFT:b.leftMove();break; case KeyEvent.VK_RIGHT:b.rightMove();break; case KeyEvent.VK_SPACE:b.leftTurn();break; } }}//处理控制类class Command implements ActionListener{ static final int button_play = 1; //给按钮分配编号 static final int button_levelup = 2; static final int button_leveldown = 3; static final int button_quit = 4; static final int button_pause = 5; static boolean pause_resume = true; int curButton; //当前按钮 GameCanvas scr;// 控制按钮类的构造方法 Command(int button,GameCanvas scr){ curButton = button; this.scr=scr; }// 按钮执行方法 public void actionPerformed (ActionEvent e){ switch(curButton){ case button_play:if(!Mytest.isPlay){ scr.initScr(); Mytest.isPlay = true; Mytest.score = 0; Mytest.scoreField.setText(“0“); Mytest.timer.resume(); } scr.requestFocus(); break; case button_levelup:if(Mytest.level 《 10){ Mytest.level++; Mytest.levelField.setText(““+Mytest.level); Mytest.score = 0; Mytest.scoreField.setText(““+Mytest.score); } scr.requestFocus(); break; case button_leveldown:if(Mytest.level 》 1){ Mytest.level--; Mytest.levelField.setText(““+Mytest.level); Mytest.score = 0; Mytest.scoreField.setText(““+Mytest.score); } scr.requestFocus(); break; case button_pause:if(pause_resume){ Mytest.timer.suspend(); pause_resume = false; }else{ Mytest.timer.resume(); pause_resume = true; } scr.requestFocus(); break; case button_quit:System.exit(0); } }}//方块类class Block { static int pattern = { {0x0f00,0x4444,0x0f00,0x4444},//用十六进至表示,本行表示长条四种状态 {0x04e0,0x0464,0x00e4,0x04c4}, {0x4620,0x6c00,0x4620,0x6c00}, {0x2640,0xc600,0x2640,0xc600}, {0x6220,0x1700,0x2230,0x0740}, {0x6440,0x0e20,0x44c0,0x8e00}, {0x0660,0x0660,0x0660,0x0660} }; int blockType; //块的模式号(0-6) int turnState; //块的翻转状态(0-3) int blockState; //快的下落状态 int row,col; //块在画布上的坐标 GameCanvas scr;// 块类的构造方法 Block(GameCanvas scr){ this.scr = scr; blockType = (int)(Math.random() * 1000)%7; turnState = (int)(Math.random() * 1000)%4; blockState = 1; row = scr.getInitRow(); col = scr.getInitCol(); }// 重新初始化块,并显示新块 public void reset(){ blockType = (int)(Math.random() * 1000)%7; turnState = (int)(Math.random() * 1000)%4; blockState = 1; row = scr.getInitRow(); col = scr.getInitCol(); dispBlock(1); }// 实现“块”翻转的方法 public void leftTurn(){ if(assertValid(blockType,(turnState + 1)%4,row,col)){ dispBlock(0); turnState = (turnState + 1)%4; dispBlock(1); } }// 实现“块”的左移的方法 public void leftMove(){ if(assertValid(blockType,turnState,row,col-1)){ dispBlock(0); col--; dispBlock(1); } }// 实现块的右移 public void rightMove(){ if(assertValid(blockType,turnState,row,col+1)){ dispBlock(0); col++; dispBlock(1); } }// 实现块落下的操作的方法 public boolean fallDown(){ if(blockState == 2) return(false); if(assertValid(blockType,turnState,row-1,col)){ dispBlock(0); row--; dispBlock(1); return(true); }else{ blockState = 2; dispBlock(2); return(false); } }// 判断是否正确的方法 boolean assertValid(int t,int s,int row,int col){ int k = 0x8000; for(int i = 0; i 《 4; i++){ for(int j = 0; j 《 4; j++){ if((int)(pattern[t][s]&k) != 0){ int temp = scr.getScrArrXY(row-i,col+j); if (temp《0||temp==2) return false; } k = k 》》 1; } } return true; }// 同步显示的方法 public synchronized void dispBlock(int s){ int k = 0x8000; for (int i = 0; i 《 4; i++){ for(int j = 0; j 《 4; j++){ if(((int)pattern[blockType][turnState]&k) != 0){ scr.drawUnit(row-i,col+j,s); } k=k》》1; } } }}//定时线程class MyTimer extends Thread{ GameCanvas scr; public MyTimer(GameCanvas scr){ this.scr = scr; } public void run(){ while(true){ try{ sleep((10-Mytest.level + 1)*100); } catch(InterruptedException e){} if(!scr.getBlock().fallDown()){ scr.deleteFullLine(); if(scr.isGameEnd()){ Mytest.isPlay = false; suspend(); }else scr.getBlock().reset(); } } }}class WinListener extends WindowAdapter{ public void windowClosing (WindowEvent l){ System.exit(0); }}