7.[Java开发之路]（5）异常

public FileInputStream(String name) throws FileNotFoundException

void Read(int index) throws ArrayIndexOutOfBoundsException // bad style
{
   ...
}

// 第一种方法
throw new EOFException();
// 第二种方法
EOFException e = new EOFException();
throw e;

String gripe = "未到指定长度，文件读取结束";
throw new EOFException(gripe);

public class FileFormatException extends Exception{
	/**
	 * 
	 */
	private static final long serialVersionUID = 1L;
	// 默认构造器
	public FileFormatException(){
		
	}
	// 带有详细描述信息的构造器
	public FileFormatException(String gripe){
		super(gripe);
	}
}

throw new FileFormatException;

package com.qunar.test;
public class ExceptionTest {
	public static void main(String[] args) {
		int a = 10;
		int b = 0;
		System.out.printf("%d / %d = %d",a,b,a/b);
		System.out.println("测试结束...");
	}
}

		try{
			code
			more code
			more code
		}
		catch (Exception e) {
			handle for this type
		}

package com.qunar.test;
public class ExceptionTest {
	public static void main(String[] args) {
		int a = 10;
		int b = 0;
		try{
			System.out.printf("%d / %d = %d",a,b,a/b);
		}
		catch (ArithmeticException e) {
			System.out.println("a / b  b 不能等于0");
		}
		System.out.println("测试结束...");
	}
}

	public void read(String name){
		try{
			InputStream inputStream = new FileInputStream(name);
			int b;
			while((b = inputStream.read()) != -1){
				// ...
			}//while
		}
		catch (IOException e) {
			e.printStackTrace();
		}
	}

	public void read(String name) throws IOException{
		InputStream inputStream = new FileInputStream(name);
		int b;
		while((b = inputStream.read()) != -1){
			// ...
		}//while
	}

        try{
			
		}
		catch (FileNotFoundException e) {
			// emergency action for missing files
		}
		catch (UnknownException e) {
			// emergency action for unknown hosts
		}
		catch (IOException e) {
			// emergency action for all other I/O problems
		}

try{
   access the database
}
catch(SQLException e){// 发生错误的细节原因
    throw new ServletException("database error:"+e.getMessage());// 只希望知道servlet是否有问题
}

try{
    access the databse
}
catch(SQLException e){
    Throwable se = new ServletException("database error");
    // 设置初始异常
    se.initCause(e);
    throw se;
}

Throwable e = se.getCause();

		try{
			
		}
		catch (Exception e) {
			
		}
		finally{
		}

package com.qunar.test;
import java.io.FileInputStream;
import java.io.IOException;
import java.io.InputStream;
public class ExceptionTest {
	public static void main(String[] args) {
		String name = "";
		InputStream in = null;
		// 确保报告出现的错误
		try{
			in = new FileInputStream(name);
			// 确保关闭输入流
			try{
				// code that might throw exceptions
			}
			finally{
				in.close();
			}
		}
		catch (IOException e) {
			// show error message 
		}	
	}
}

package com.qunar.test;
public class ExceptionTest {
	public static int function(int n){
		try{
			int r = n * n;
			return r;
		}
		finally{
			if(n == 2){
				return 0;
			}//if
		}//finally
	}
	public static void main(String[] args) {
		System.out.println(function(2));
	}
}

InputStream in = ...;
try{
    // code that might throw exceptions
}
finally{
    in.close();			
}