经典的异常

/**运行时异常*/public class I {public static void main(String []args){ int a=10/0; System.out.println(a);}}结果：[color=red]Exception in thread "main" java.lang.ArithmeticException: / by zeroat User.I.main(I.java:8)[/color]2.public class I {public static void main(String []args){int a[]={1,2,3};System.out.print(a[4]);}}结果：[color=red]Exception in thread "main" java.lang.ArrayIndexOutOfBoundsException: 4at User.I.main(I.java:14)[/color]把异常处理了public class I {public static void main(String []args){/* int a=10/0; System.out.println(a); */int a[]={1,2,3};try {System.out.print(a[4]);} catch (Exception e) {// TODO: handle exception}}}结果：       空白无论是否存在异常,到了finally一定执行:public class I {public static void main(String []args){/* int a=10/0; System.out.println(a); */int a[]={1,2,3};try {System.out.print(a[4]);} catch (Exception e) {// TODO: handle exception}finally{System.out.print(a[4]);}}}结果：[color=red]Exception in thread "main" java.lang.ArrayIndexOutOfBoundsException: 4at User.I.main(I.java:19)

注意：

一般情况finally代码块，一般是用来关闭资源的，例如 数据库流 close.conn();