Java实用教程第二版常用语句

1、import java.applet.*;import java.awt.*;public class Boy extends Applet public void paint (Graphics g) g.setColor(Color.red); g.drawString(我一边喝着咖啡，一边学Java呢,5,30); g.setColor(Color.blue); g.drawString(我学得很认真,10,50); public class Ex3 public static void main (String args) long sum=1,temp=1; for (int i=2

2、;i=10;i+) temp=temp*i; sum=sum+temp; System.out.println(1!+2!+.+10!=+sum); public class Ex4 public static void main(String args) int i=1;int j; while(i=1000) i+; for (j=2;ji;j+) if (i%j=0) break; if(i=j) System.out.println(i+是素数); public class Ex6 public static void main(String args) int sum; for(in

3、t i=2;i=1000;i+) sum=0; for( int j=1;jc?a:c;d=d2b?d:b;System.out.println(b);public class Hello public static void main (String args) System.out.println(你好，很高兴学习Java); import java.lang.*;class Trangle double a,b,c,p; boolean s; Trangle(double a,double b,double c) this.a=a;this.b=b;this.c=c; public do

4、uble 周长() return a+b+c;public double 求面积() p=(a+c+b)/2; return Math.sqrt(p*(p-a)*(p-b)*(p-c);void judgeTrangle() if (a+b)c & (a+c)b & (b+c)a) s=true; else s=false; class Leder double ub,db,h; Leder(double ub,double db,double h) this.ub=ub;this.db=db;this.h=h; double 面积() return (ub+db)*h)/2; class C

5、ircle double r; double pi=3.; Circle(double r) this.r=r; double 求周长() return 2*r*pi; double area() return r*r*pi; public class Example public static void main (String args) Trangle sanjiao; Leder tixing;Circle yuan;sanjiao=new Trangle(3.0,4.0,5.0);System.out.println(三角形的周长：+sanjiao.周长();System.out.p

6、rintln(三角形的面积：+sanjiao.求面积();tixing=new Leder(2.0,4.0,1.0);System.out.println(梯形的面积：+tixing.面积();yuan=new Circle(3.0);System.out.println(圆的周长：+yuan.求周长();System.out.println(圆的面积：+yuan.area();class Company Employee employee; double salaries=0; Company(Employee employee) this.employee=employee; public

7、 double salariesPay() salaries=0; for (int i = 0; i employee.length; i+) if (YearWorker.class.isInstance(employeei) salaries += employeei.earnings(); if (MonthWorker.class.isInstance(employeei) salaries += employeei.earnings() * 12; if (WeekWorker.class.isInstance(employeei) salaries += employeei.ea

8、rnings() * 52; /计算salaries。 return salaries; abstract class Employee public abstract double earnings(); /声明一个公有的抽象方法earnings,方法返回类型为doublepublic class HardWork public static void main(String args) Employee employee=new Employee20; for(int i=0;i=0) root1=(-b+Math.sqrt(disk)/(2*a); root2=(-b-Math.sqrt

9、(disk)/(2*a); System.out.printf(方程的根:%f,%fn,root1,root2); else System.out.printf(方程没有实根n); else System.out.println(不是一元2次方程); public void setCoefficient(double a,double b,double c) this.a=a; this.b=b; this.c=c; if(a!=0) boo=true; else boo=false; import tom.jiafei.*;class SunRise public static void m

10、ain(String args ) SquareEquation equation=new SquareEquation(4,5,1); equation.getRoots(); equation.setCoefficient(-3,4,5); equation.getRoots(); public class EditString public static StringBuffer edit(String s) StringBuffer result=new StringBuffer(); for(int i=0;i=a & s.charAt(i)=A & s.charAt(i)=Z) r

11、esult.append(s.charAt(i); return result; public class Example public static void main(String args) String s=student Z 12 name 56, java.; System.out.println(EditString.edit(s); import java.util.Date;import java.text.SimpleDateFormat;class Example1 public static void main(String args) Date nowTime=new

12、 Date(); SimpleDateFormat matter1=new SimpleDateFormat(北京时间:E HH:mm:ss); System.out.println(matter1.format(nowTime); import java.io.*;import java.util.*;public class Example2 public static void main(String args) throws IOException int year,month; String str; BufferedReader br=new BufferedReader(new

13、InputStreamReader(System.in); str=br.readLine(); year=Integer.parseInt(str); str=br.readLine(); month=Integer.parseInt(str); System.out.println(year+年+month+月); int allDay; if(year%4=0&year%100!=0)|(year%400=0)if (month=2) allDay=29; if(month=1|month=3|month=5|month=7|month=8|month=10|month=12) allD

14、ay=31; else allDay=30;elseif(month=2) allDay=28; else if(month=1|month=3|month=5|month=7|month=8|month=10|month=12) allDay=31; else allDay=30; System.out.println( 日 一 二 三 四 五 六); Calendar 日历=Calendar.getInstance();日历.set(year,month-1,1);int 星期几=日历.get(Calendar.DAY_OF_WEEK)-1;String a=new String星期几+a

15、llDay;for(int i=0;i星期几;i+) ai=*;for(int i=星期几,n=1;i星期几+allDay;i+)if(n=9)ai=String.valueOf(n)+ ;elseai=String.valueOf(n) ;n+;for(int i=0;ia.length;i+)if(i%7=0)System.out.println();System.out.print( +ai); import java.awt.*; import java.awt.event.*; import java.util.*; class WindowTextArea extends Fram

16、e implements TextListener TextArea text1,text2; WindowTextArea(String s) super(s); setLayout(new FlowLayout();text1=new TextArea(5,23); text2=new TextArea(5,23); add(text1); add(text2); text2.setEditable(false); text1.addTextListener(this); addWindowListener(new WindowAdapter() public void windowClo

17、sing(WindowEvent e) System.exit(0); ); setBounds(100,100,400,160); setVisible(true); validate(); public void textValueChanged(TextEvent e) String s=text1.getText(); StringTokenizer geshu=new StringTokenizer(s); int n=geshu.countTokens(); double a=new doublen; for(int i=0;in;i+) String temp=geshu.nex

18、tToken(); double date=Double.parseDouble(temp); ai=date; double sum=0,average; for(int i=0;in;i+) sum=sum+ai; average=sum/n; text2.setText(null); text2.append(和:+sum+n+平均数:+average); public class Example public static void main(String args) WindowTextArea win=new WindowTextArea(计算的窗口); import java.a

19、wt.*; import java.awt.event.*; class WindowTextArea extends Frame implements ActionListener TextField text1,text2,text3; Button button1,button2,button3,button4; WindowTextArea(String s) super(s); setLayout(new FlowLayout(); text1=new TextField(10); text2=new TextField(10); text3=new TextField(17); b

20、utton1=new Button(加); button2=new Button(差); button3=new Button(积); button4=new Button(除); add(text1); add(text2); add(text3); text3.setEditable(false); add(button1); add(button2); add(button3); add(button4); button1.addActionListener(this); button2.addActionListener(this); button3.addActionListener

21、(this); button4.addActionListener(this); addWindowListener(new WindowAdapter() public void windowClosing(WindowEvent e) System.exit(0); ); setBounds(100,100,160,180); setVisible(true); validate(); public void actionPerformed(ActionEvent e) double num1=0,num2=0,totle=0; try num1= Double.parseDouble(t

22、ext1.getText(); num2= Double.parseDouble(text2.getText(); if(e.getSource()=button1) totle=num1+num2; text3.setText(和:+totle); else if(e.getSource()=button2) totle=num1-num2; text3.setText(差:+totle); else if(e.getSource()=button3) totle=num1*num2; text3.setText(积:+totle); else if(e.getSource()=button

23、4) totle=num1/num2; text3.setText(商:+totle); catch(NumberFormatException event) System.out.println(event);text3.setText(请输入数字!); public class Example public static void main(String args) WindowTextArea win=new WindowTextArea(计算); import java.awt.*; import java.awt.event.*; class Mycanvas extends Can

24、vas int x,y,w,h; Mycanvas() setBackground(Color.pink); setForeground(Color.YELLOW); public void setX(int x) this.x=x; public void setY(int y) this.y=y; public void setW(int w) this.w=w; public void setH(int h) this.h=h; public void paint(Graphics g) g.fillRect(x,y,w,h); class WindowCanvas extends Fr

25、ame implements ActionListener Mycanvas canvas; TextField text1,text2,text3,text4; Button button; WindowCanvas() canvas=new Mycanvas(); text1=new TextField(4); text2=new TextField(4); text3=new TextField(5); text4=new TextField(5);text1.setBackground(Color.red);text1.setForeground(Color.black);text2.

26、setBackground(Color.red);text2.setForeground(Color.cyan);text3.setBackground(Color.red);text3.setForeground(Color.blue);text4.setBackground(Color.red);text4.setForeground(Color.gray);Panel pNorth=new Panel(),pSouth=new Panel();pNorth.setBackground(Color.green);pNorth.setForeground(Color.orange);pSou

27、th.setBackground(Color.green);pSouth.setForeground(Color.orange);button=new Button(确定); button.addActionListener(this);button.setBackground(Color.yellow);button.setForeground(Color.blue);pNorth.add(new Label(矩形的宽: ); pNorth.add(text3); pNorth.add(new Label(矩形的高: ); pNorth.add(text4); pSouth.add(new

28、Label(左上角位置坐标:); pSouth.add(text1); pSouth.add(text2); pSouth.add(button); addWindowListener(new WindowAdapter() public void windowClosing(WindowEvent e) System.exit(0); ); add(canvas,BorderLayout.CENTER); add(pNorth,BorderLayout.NORTH); add(pSouth,BorderLayout.SOUTH); setBounds(100,100,500,500); se

29、tVisible(true); validate(); public void actionPerformed(ActionEvent e) int x,y,w,h; try x=Integer.parseInt(text1.getText(); y=Integer.parseInt(text2.getText(); w=Integer.parseInt(text3.getText(); h=Integer.parseInt(text4.getText(); canvas.setX(x); canvas.setY(y); canvas.setW(w); canvas.setH(h); canv

30、as.repaint(); catch(NumberFormatException ee) x=0;y=0;w=0;h=0; public class Example7_18 public static void main(String args) new WindowCanvas(); import java.awt.*;import java.awt.event.*;class MyWin extends Frame implements ActionListener Button button; Label label; MyWin() setLayout(null); Cursor c

31、=Cursor.getPredefinedCursor(Cursor.HAND_CURSOR); setCursor(c); button=new Button(横向走动); button.setBackground(Color.pink); button.addActionListener(this); label=new Label(我可以被碰掉,Label.CENTER); label.setBackground(Color.yellow); button.setCursor(Cursor.getPredefinedCursor(Cursor.MOVE_CURSOR); add(butt

32、on); add(label); button.setBounds(20,80,80,20); label.setBounds(150,80,80,20); setVisible(true); setBounds(100,120,300,300); validate(); public void actionPerformed(ActionEvent e) Rectangle rect=button.getBounds(); int x=(int)rect.getX(); int y=(int)rect.getY(); if(ersects(label.getBounds()

33、label.setVisible(false); if(label.isVisible() x=x+2; button.setLocation(x,y); else y=y+3; button.setLocation(x,y); button.setLabel(纵向走动); public class Example7_23 public static void main(String args) MyWin win=new MyWin(); import java.awt.*; import java.awt.event.*; class WindowCursor extends Frame implements ActionListener Button button1,button2; TextField text; int n=-1; WindowCursor() button1=new Button(单击我); text=new TextField(将鼠标放在上面的按钮上看形状); button2=new Button(看看鼠标的形状); add(button1,BorderLayout.NORTH); add(button2,BorderLayout.CENTER);