java基础异常及常见包

1、partll异常及常见包 了解常见的异常异常说明exception异常层次结构的根类run timeexception许多java.lang异常的基类arithmeticexception算术错误情形，如以零作除数illegalargumentexception方法接收到非法参数arraylndexoutofboundexception数组犬小小于或大于实际的数组犬小n u 11 po i n t ere xcept i o n尝试访问null对象成员classnotfou ndexception不能加载所需的类numberformatexception数字轻化格式异常，比如字符串钊float

2、 型数字的转择无轴ioexceptioni/o异常的根类filenotfoundexcepti on找不到文件eofexception文件结束i nterru pted e xcepti o n线程中断型匚從解决异常的方式：()用try catch和finally语句 语句结构：如下：try 需要排除异常的代码catch(exception e)/ exception e异常处理代码 finally程序结束前的执行的代码案例应用：源代码如下:package com.workitparti;publie class demol / * * param args/public static voi

3、d main(string args) / todo auto-generated method stubdemol div = new demol();tryint temp = div.div(10, 0 );system, out. print in (11 temp = ”+t emp);catch(arithmeticexception e)system.out.printin (n除数不能为零!输入错误！ ! ”)；system, out .printin (e . tostring () ) ; /输出错误处finallysystem, out. printin ( ”n=程序结

4、束=“); public int div (int first, int second)int result = 0;result = first/second;return result;多重try catch的应用(根类在前时就捕获不到在后了类的错误)案例应用： 源代码如下: package com.workit.parti;public class demo2 / * * param args*/public static void m=in(string args)/ todo auto-generated method stubdemo2 data = new demo2();str

5、ing str = (u10uz utn；datatest(str);public void test (string str) try try system.outprintin(=h+integer.parseint(str1 ); catch (arrayindexoutofboundsexception e) system, out .print in (u数组溢出，请重新输入！ ！ ”)； e.printstacktrace ();catch (numberformatexception e) / todo auto-generated catch blocksystem, out

6、.printin (”输入错误！非字符型字符串无法转 化成整型！ ! ! h + f,nf,+e.tostring();double datal = double.parsedouble(str0); double data3 = math.po(datal, 2 );system.out.printin(hdatal = n+datal);system, out. pri nt in (” datal 的平方为：n+data3); catch (numbeiformmtexception e) / todo auto-generated catch blocksystem. out. pri

7、nt in ("输入错误！输入的字符需为数字！ ！ ！ n + ,fn,f+e . tostring ();finallysystem.out.printin colection 接口arraylist对彖相当丁是动态数组 案例应用：源代码如下:指定类型的package com.workit.parti;import java.util.arraylist;import java.util.list;public class demo3 / * param args*/public static void main(string args) / todo auto-genested

8、method stublist<string> list = new arraylist<string> (); list. add ( nlemon'1);list.add("tom”);list.add ( "rose");list add(n jack");for (int i = 0; idist size () ; i + +) system.outprintin (list.get(i) -tostring ();案例二：package comworkit.parti;public class student

9、private string name;private string stdid;private string origin;private int age;public student(string namez string stdid, string origin, int age) super();this .name = name;this.stdid = stdid;this < origin = origin;this.age = age;public string getname()return name;public string getstdid()return std

10、id;public string getorigin()return origin;public int getage()return age;package com.workit.parti;import java.util.arraylist;import javautillist;public class demo4 / * * param args/public static void main(string args) / todo auto-generated method stublist<student> student = new arraylist<stu

11、dent>();/装箱for (int i = 1;i<=100;i+)student add (new student ( nworkit,f+ iz ”num11 + i, nchiann z i); /拆箱system, out .printin (“姓名tt学号籍贯t年龄");for (int j = 0 ;j< student.size();j+)system. out. print in ( (n + s tuden t get ( j ) . getname () + n t ” + student.get(j) .getstdid()+ ht n +

12、 student get ( j) . getorigin () ) +,f tn + studentget ( j) .getage ();案例三：未指定类型的package com.workitparti;import javautil.arraylist;import javautil.list;public class demo5 / * * param args*/public static void main(string args) / todo auto-genetmted method stublist list = new arraylist ();list add(&qu

13、ot;lemon”)；listadd(new integer (4);list.mdd(67);student std = new student ( htom,t, ,tworkit01,t, ,tusa,t z 21); listadd(std);for(int i = 0;i<list.size();i+)system.out.printin("list" + i + "=" +listget (i) .tostring ();student stdudent = (student)list.get(list.size()-1);system

14、, out. print in ("其中学生信息为：;system, out. printin (” 姓名 t 学号t 籍贯 t 年龄”);sys tern, out: print in (stdudent getname ()+ ,f=,f +stdudent getstdid () + ,r=n +stdudent getorigin () + ,r=n +stdudent getage (); hashmap 实现了 map 接口案例应用；源代码如:package com.workitpart 1;import java.util.hashmap;import javautil

15、-map;public class demo6 / * * param args*/public static void main(string args) / todo auto-generated method stubmap<string , student> studmap = new hashmap<string, student>(); for(int i = 0;i<10;i+)student stud = new student (nworkit fl + i, nnumfl + i, "usa j i); studmap.put (flstudentu + i, stud);s