Java考试参考

1、1.编写一个类，该类创建的对象可以计算等差数列的和。代码：class leisum static int qsz,bcz,xs,sum;leisum(int a,int b,int c)qsz=a; bcz=b; xs=c;int sum() return sum=xs*qsz+xs*(xs-1)/2*bcz; class examplepublic static void main(string args) int sum=0; leisum leisum=new leisum(1,1,100);sum= leisum.sum();system.out.println("等差数列的

2、和为："+sum);2.编写一个类，该类封装了一元二次方程共有的属性和功能，既该类有刻画方程系数的3个成员变量以及计算实根的方法。要求：该类的所有对象共享常数项。代码：class laderdouble a,b; static double c; double x1,x2; boolean boo; public lader(double a,double b,double c) this.a=a; this.b=b; lader.c=c;public void getroots() if(a!=0) system.out.println("一元2次方程:");

3、double d=b*b-4*a*c; if(d>=0)x1=(-b+math.sqrt(d)/(2*a);x2=(-b-math.sqrt(d)/(2*a); system.out.printf("方程的根:x1=%f,x2=%fn",x1,x2);else system.out.printf("方程没有实根n"); else system.out.println("不是一元2次方程"); public class liti2_5public static void main(string args )lader reluct

4、ance1=new lader(2,5,1); lader reluctance2=new lader(3,2,2);reluctance1.getroots(); reluctance2.getroots(); 3.编写一个应用程序，用户从键盘输入一行字符串，程序输出该字符串中与模式”24680a135792”匹配的子字符串。代码：import java.util.scanner;import java.util.regex.*;public class one public static void main(string args)system.out.println("请输入一

5、行字符串："); scanner reader=new scanner(system.in);string str=reader.nextline();pattern p=ppile("24680a135792");matcher m=p.matcher(str);while(m.find() string s=m.group();system.out.print("从"+m.start()+"到"+m.end()+"匹配模式子序列：");system.out.println(s); 4. 编写一个应用程

6、序，将用户从键盘输入的10行文字存入文件。代码：import java.io.*;import java.util.*;public class one public static void main(string args)scanner reader=new scanner(system.in);try fileoutputstream writefile=new fileoutputstream("hello.txt");int line=1,n=10;system.out.println("输入"+n+"行文本，并存入磁盘："

7、);while(line<=n)string s=reader.nextline();byte buffer=s.getbytes();writefile.write(buffer,0,buffer.length); line+;writefile.close();catch(ioexception e)system.out.println("error "+e);file f=new file("hello.txt");try int i=-1; randomaccessfile random=new randomaccessfile(f,&qu

8、ot;rw");random.seek(0);long m=random.length();while(i!=m) i+; random.seek(i); int c=random.readbyte();if(c<=255&&c>=0) system.out.print(char)c); else m-;random.seek(m); byte cc=new byte2;random.readfully(cc); system.out.print(new string(cc); random.close();catch(ioexception ee)5.用

9、randomaccessfile流将一个文本文件倒置读出。代码：import java.io.*;public class animator public static void main(string args) file f=new file("hello.txt");tryrandomaccessfile random=new randomaccessfile(f,"rw");random.seek(0);long m=random.length();while(m>=0)m=m-1;random.seek(m);int c=random.r

10、eadbyte(); if(c<=255&&c>=0) system.out.print(char)c);elsem=m-1; random.seek(m); byte cc=new byte2;random.readfully(cc);system.out.print(new string(cc);random.close();catch(ioexception ee)6.图形用户设计用jframe创建一个带有菜单的窗口。代码：import javax.swing.*;public class animentpublic static void main(stri

11、ng args)firstwindow win= new firstwindow("菜单练习");class firstwindow extends jframejmenubar menubar=new jmenubar();menu menu1=new menu("文件");menu menu2=new menu("编辑");jmenuitem itema=new jmenuitem("打开");jmenuitem item=new jmenuitem("退出");jmenuitem item

12、c=new jmenuitem("剪切");jmenuitem item=new jmenuitem("复制");firstwindow(string s)set title(s); set size(160,170);set location(120,120); set visible(true); menu1.add(itema);menu1.add(item); menu2.add(itemc); menu2.add(item); menubar.add(menu1);menubar.add(menu2); setjmenubar(menubar)

13、;validate(); setdefaultcloseoperation(jframe.dispose_on_close);7.选项卡窗格添加6个按钮，在单击按钮时在窗体中分别显示6幅图片。代码：import javax.swing.*;import java.awt.*;public class animentpublic static void main(string args)new mycard();class mycard extends jframe jtabbedpane p; icon icon;string imagename="a.jpg","

14、;b.jpg","c.jpg","d.jpg","e.jpg","f.jpg"public mycard() setbounds(100,100,500,300); set visible(true);icon =new iconimagename.length;for(int i=0;i<icon.length;i+)iconi=new imageicon(imagenamei);p=new jtabbedpane(jtabbedpane.left);for(int i=0;i<icon.l

15、ength;i+) int m=i+1; p.add("第"+m+"张图片",new jbutton(iconi);p.validate(); add(p,borderlayout.center); validate();setdefaultcloseoperation(jframe.dispose_on_close);8.设置一个窗口，里面有两个文本框，如果在第一个文本框输入的全部是数字字符，计算它的平方并显示在第二个文本框中，如果包括非数字字符，就将整个字符串显示在第二个文本框中，并且在命令行输出其字符串的长度。代码：import java.awt.

16、*;import java.awt.event.*;import javax.swing.*;import java.math.*;public class onepublic static void main(string args)mathwindow win=new mathwindow();class mathwindow extends jframejtextfield inputtext,showtext;mathwindow()inputtext=new jtextfield(10); showtext=new jtextfield(10);inputtext.addaction

17、listener(new actionlistener()public void actionperformed(actionevent e)string s=inputtext.gettext();trybiginteger n=new biginteger(s);n=n.pow(2);showtext.settext(n.tostring();catch(numberformatexception ee)jtextfield t1=(jtextfield) (e.getsource();string str=t1.gettext();showtext.settext(str);system

18、.out.println(str.length(););setlayout(new flowlayout(); add(inputtext);add(showtext);setbounds(100,100,200,120); set visible(true); validate(); setdefaultcloseoperation(jframe.dispose_on_close);9. 编写一个应用程序，设计4个按钮，分别命为：“加”、“差”、“乘”、“除”；还有3个文本框，单击相应的按钮，将两个文本框的数字做运算，在第三个文本框中显示结果。import java.awt.*;import

19、 java.awt.event.*;import javax.swing.*;public class one public static void main(string args) computerframe one=new computerframe();one.settitle("计算"); class computerframe extends jframe implements actionlistener jtextfield texta,textb,textshow;jbutton button1,button2,button3,button4;jlabel

20、 label;public computerframe()setlayout(new flowlayout(); texta=new jtextfield(10);textb=new jtextfield(10); textshow=new jtextfield(10); label=new jlabel(" ",jlabel.center);label.setbackground(color.green); add(texta); add(label); add(textb);add(textshow); button1=new jbutton("加"

21、); button2=new jbutton("减"); button3=new jbutton("乘"); button4=new jbutton("除"); add(button1); add(button2);add(button3); add(button4); button1.addactionlistener(this); button2.addactionlistener(this); button3.addactionlistener(this); button4.addactionlistener(this); se

22、t size(420,120); set visible(true); addwindowlistener(new windowadapter()public void windowclosing(windowevent e)system.exit(0););validate();public void actionperformed(actionevent e) double n; if(e.getsource()=button1)double n1,n2;try n1=double.parsedouble(texta.gettext(); n2=double.parsedouble(tex

23、tb.gettext(); n=n1+n2;textshow.settext(string.valueof(n); label.settext("+");catch(numberformatexception ee) textshow.settext("请输入数字字符");else if(e.getsource()=button2) double n1,n2; try n1=double.parsedouble(texta.gettext();n2=double.parsedouble(textb.gettext(); n=n1-n2;textshow.

24、settext(string.valueof(n); label.settext("-");catch(numberformatexception ee) textshow.settext("请输入数字字符");else if(e.getsource()=button3)double n1,n2;try n1=double.parsedouble(texta.gettext(); n2=double.parsedouble(textb.gettext(); n=n1*n2; textshow.settext(string.valueof(n);label

25、.settext("*"); catch(numberformatexception ee)textshow.settext("请输入数字字符");else if(e.getsource()=button4)double n1,n2; try n1=double.parsedouble(texta.gettext(); n2=double.parsedouble(textb.gettext(); n=n1/n2; textshow.settext(string.valueof(n); label.settext("/");catch(

26、numberformatexception ee) textshow.settext("请输入数字字符");validate();10.分别用三个单选按钮，控制三张不同的图片import javax.swing.*;import java.awt.*;import java.awt.event.*;public class anepublic static void main(string args)new rbuttonwindow(); class rbuttonwindow extends jframe implements itemlistenerjradiobut

27、ton rbuttona,rbuttonb,rbuttonc;buttongroup g; panel p; jlabel imagelabel; icon pic1,pic2,pic3;rbuttonwindow()g=new buttongroup();rbuttona=new jradiobutton("图片1");rbuttonb=new jradiobutton("图片2");rbuttonc=new jradiobutton("图片3");g.add(rbuttona);g.add(rbuttonb);g.add(rbut

28、tonc);p=new jpanel();p.add(rbuttona);p.add(rbuttonb);p.add(rbuttonc);imagelabel=new jlabel();pic1=new imageicon("a.jpg"); pic2=new imageicon("b.jpg");pic3=new imageicon("c.jpg");add(p,borderlayout.south);add(imagelabel,borderlayout.center);validate();rbuttona.additemlis

29、tener(this);rbuttonb.additemlistener(this);rbuttonc.additemlistener(this);setbounds(280,80,500,600);set visible(true);setdefaultcloseoperation(jframe.dispose_on_close);public void itemstatechanged(itemevent e)try if(rbuttona.isselected()imagelabel.seticon(pic1); catch(numberformatexception ee) try i

30、f(rbuttonb.isselected()imagelabel.seticon(pic2); catch(numberformatexception ee) try if(rbuttonc.isselected()imagelabel.seticon(pic3); catch(numberformatexception ee) 11.编写一个应用程序，使用弹出式菜单在两个文本框中实现“剪切”，“复制”，“粘贴”的操作。代码：import javax.swing.*;import java.awt.event.*;import java.awt.*;public class com publ

31、ic static void main(string args)editwindow win=new editwindow("窗口");class editwindow extends jframe implements actionlistenerjpopupmenu menu; jsplitpane splitpane;jmenuitem itemcopy, itemcut, itempaste;jtextarea inputtext, showtext;editwindow(string s)set title("弹出式菜单");set size(

32、260,270);set location(120,120); set visible(true);menu=new jpopupmenu();itemcut=new jmenuitem("剪切");itemcopy=new jmenuitem("复制");itempaste=new jmenuitem("粘贴");menu.add(itemcut);menu.add(itemcopy);menu.add(itempaste);inputtext=new jtextarea(); showtext=new jtextarea();jp

33、anel panel=new jpanel();panel.setlayout(new gridlayout(1,2);panel.add(new jscrollpane(inputtext);panel.add(new jscrollpane(showtext);inputtext.addmouselistener(new mouseadapter()public void mousepressed(mouseevent e)if(e.getmodifiers()=inputevent.button3_mask)menu.show(inputtext,e.getx(),e.gety(););

34、showtext.addmouselistener(new mouseadapter()public void mousepressed(mouseevent e)if(e.getmodifiers()=inputevent.button3_mask)menu.show(showtext,e.getx(),e.gety(););splitpane=new jsplitpane(jsplitpane.horizontal_split,inputtext,showtext);splitpane.setdividerlocation(120);add(splitpane,borderlayout.c

35、enter);itemcopy.addactionlistener(this);itemcut.addactionlistener(this);itempaste.addactionlistener(this); validate();setdefaultcloseoperation(jframe.dispose_on_close);public void actionperformed(actionevent e)if(e.getsource()=itemcopy)inputtext.copy();else if(e.getsource()=itemcut)inputtext.cut();e

36、lse if(e.getsource()=itempaste)showtext.paste();12. 编写一个应用程序，有2个按钮，用户通过按动键盘上的方向键移动这些按钮。代码：import javax.swing.*;import java.awt.*;import java.awt.event.*;public class compublic static void main(string args)new win();class win extends jframe implements keylistener,focuslistenerjbutton button1,button2; int x1=0,x2=