JAVA范例 四）异常处理---编译时异常、运行时异常

实例35  除0发生的算术异常（ArithmeticException）

public class Runtime_01 {
	public static void main(String[] args) {
		for (int i = 10; i > 0; i--) {
			System.out.print(" " + (i / (i - 1)));
			if (i % 5 == 0)
				System.out.println();
		}
	}
}

 

实例36  数组下标越界异常

public class Runtime_02 {
	public static void main(String[] args) {
		int a[] = new int[5];
		for (int i = 0; i < 10; i++) {
			a[i] = i + 1;
			System.out.print(" " + a[i]);
		}
	}
}

 

实例37  数组元素类型不匹配异常

public class Runtime_03 {
	public static void main(String[] args) {
		Object obj[] = new String[5];
		for (int i = 0; i < obj.length; i++) {
			obj[i] = new Integer(i);
			System.out.print(" " + obj[i]);
		}
	}
}

 

实例38  强制类型转换异常

public class Runtime_04 {
	public static void main(String[] args) {
		Object x = new Integer(0);
		System.out.println((String) x);
	}
}

 

实例39  索引越界异常

public class Runtime_05 {
	public static void main(String[] args) {
		int[] array = new int[5];
		for (int i = 0; i < array.length; i++) {
			array[i] = i;
		}
		for (int i = 1; i <= array.length; i++) {
			System.out.print(array[i - 1] + " " + array[i]);
		}
	}
}

 

实例40  空指针异常

public class Runtime_06 {
	static Test test;
	public static void main(String[] args) {
		System.out.println(test.talk());
	}
}
class Test {
	public String talk() {
		return "this is a boy";
	}
}

 

实例41  数字格式转换异常

public class Runtime_07 {
	private String name;
	private String password;
	public String getName() {
		return name;
	}
	public void setName(String name) {
		this.name = name;
	}
	public String getPassword() {
		return password;
	}
	public void setPassword(String password) {
		this.password = password;
	}
	public static void main(String[] args) {
		Runtime_07 r7 = new Runtime_07();
		String name = r7.getName();
		int password = new Integer(r7.getPassword()).intValue();
		System.out.println("用户名为" + name + ";密码为" + password);
	}
}

 

实例42  字符串索引越界异常

public class Runtime_08 {
	public static void main(String[] args) {
		String str = "This is a StringIndexOutBounds";
		char ch = str.charAt(30);
		System.out.println(ch);
	}
}

 

实例43  操作错误（UnsupportedOperationException）

import java.util.ArrayList;
import java.util.Arrays;
import java.util.List;

public class Runtime_09 {
	public static void main(String[] args) {
		String[] listArray = new String[2];
		List list = Arrays.asList(listArray);
		List list1 = new ArrayList(list);
		list1.add("hello");
		listArray[0] = "china";
		list.add("world");		// 抛出操作错误异常
		System.out.println(list.get(0) + "," + list.get(1));
	}
}

 

实例44  找不到指定类时发生的异常（ClassNotFoundException）

    这里没有提供MySQL的JDBC驱动文件，所以异常

package Chapter04.check;

import java.sql.Connection;
import java.sql.DriverManager;
import java.sql.ResultSet;
import java.sql.Statement;

public class CheckException_01 {
	public static void main(String[] args) throws Exception {
		Connection conn = null;
		Statement stmt = null;
		ResultSet rst = null;
		String s = "";
		Class.forName("com.mysql.jdbc.Driver");
		// 注册驱动程序
		conn = DriverManager.getConnection(
				"jdbc:mysql://localhost:3306/myuser", "root", "root");
		// 获得数据库的连接
		stmt = conn.createStatement();
		// 创建会话声明
		rst = stmt.executeQuery("select * from user");
		while (rst.next()) {
			System.out.print(s = new String(rst.getString(1).getBytes(
					"ISO-8859-1"), "GBK")
					+ "--");
			System.out.print(s = new String(rst.getString(2).getBytes(
					"ISO-8859-1"), "GBK")
					+ "--");
			System.out.print(s = new String(rst.getString(3).getBytes(
					"ISO-8859-1"), "GBK")
					+ "--");
			System.out.print(s = new String(rst.getString(4).getBytes(
					"ISO-8859-1"), "GBK"));
			System.out.println();
		}
	}
}

 

实例45 请求的方法不存在

 UserAction.java

package chp10;
import java.util.Date;

import com.opensymphony.xwork2.ActionSupport;

public class UserAction extends ActionSupport {//定义一个UserAction类并使之继承ActionSupport
	private String name;
	private String password;
	private String date = new Date().toLocaleString();
	public String getDate() {
		return date;
	}
	public void setDate(String date) {
		this.date = date;
	}
	public String getName() {
		return name;
	}
	public void setName(String name) {
		this.name = name;
	}
	public String addName() {
		System.out.println(this.getName() + "   " + this.getPassword()
				+ " hjhjhj");
		if (!this.getPassword().equals("") && !this.getName().equals("")) {
			return "success";
		} else {
			return "fail";
		}
	}
	public String getPassword() {
		return password;
	}
	public void setPassword(String password) {
		this.password = password;
	}
}

 

 struts.xml                       这里事实上不存在add方法，当使用check.action时出现异常

<?xml version="1.0" encoding="UTF-8"?>

<!DOCTYPE struts PUBLIC
    "-//Apache Software Foundation//DTD Struts Configuration 2.0//EN"
    "http://struts.apache.org/dtds/struts-2.0.dtd">
	
	
<struts>
	<package name="package" extends="struts-default">
		<action name="check" class="chp10.UserAction" method="add">	
			<result name="success">/success.jsp</result>
			<result name="fail">/fail.jsp</result>
	</action>		
	</package>
</struts>

 web.xml

<?xml version="1.0" encoding="UTF-8"?>
<web-app version="2.5" 
	xmlns="http://java.sun.com/xml/ns/javaee" 
	xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" 
	xsi:schemaLocation="http://java.sun.com/xml/ns/javaee 
	http://java.sun.com/xml/ns/javaee/web-app_2_5.xsd">
	
	
	<filter>
	<filter-name>struts2</filter-name>
	<filter-class>org.apache.struts2.dispatcher.FilterDispatcher</filter-class>
	</filter>	
	<filter-mapping>
	<filter-name>struts2</filter-name>
	<url-pattern>/*</url-pattern>
	</filter-mapping>
	
  <welcome-file-list>
    <welcome-file>index.jsp</welcome-file>
  </welcome-file-list>
</web-app>

这里struts2用到的jar包：

commons-logging-1.1.jar

freemarker-2.3.8.jar

ognl-2.6.11.jar

struts2-core-2.0.6.jar

xwork-2.0.1.jar