Java要点和《疯狂Java讲义》例程整理(六)

throw 用法

import java.io.FileInputStream;
import java.io.IOException;

public class Test {
	public static void test() throws IOException
	{
		throw new IOException("haha");
	}
	public static void main(String[] args)
	{
		try{
			test();
		}
		catch(IOException e)
		{
			System.out.println(e.getMessage());
		}
	}
}

haha

自定义异常类

public class AuctionException extends Exception
{
	public AuctionException(){}
	
	public AuctionException(String msg)
	{
		super(msg);
	}
}

Throw All

try
{
...
}
catch (Throwable t)
{
...
}

练习

import java.io.IOException;

import javax.swing.JFrame;

public class Test {
	public static void main(String[] args)
	{
		int i;
		for(i=0; i<3; i++)
		{
			try{
				System.out.println("i="+i);
				throw new MyException();
			}
			catch(MyException e)
			{
				System.out.println(e.Say());
			}
		}
	}
}

class MyException extends Exception
{
	static int intNumber = 0;
	MyException()
	{
		intNumber++;
	}
	String Say()
	{
		return "No"+intNumber+":MyException!";
	}
}

i=0
No1:MyException!
i=1
No2:MyException!
i=2
No3:MyException!

IO

FIle类

IO流

对象序列化

import java.io.FileInputStream;
import java.io.FileOutputStream;
import java.io.IOException;
import java.io.ObjectInputStream;
import java.io.ObjectOutputStream;
import java.io.Serializable;

public class Test {
	public static void main(String[] args) throws Exception
	{
		try{
			ObjectOutputStream oos = new ObjectOutputStream(new FileOutputStream("object.txt"));
			Person per = new Person("Tom", 13);
			oos.writeObject(per);
			oos.close();
		}
		catch(IOException e)
		{
			e.printStackTrace();
		}
		
		try{
			ObjectInputStream ois = new ObjectInputStream(new FileInputStream("Object.txt"));
			Person p = (Person)ois.readObject();
			System.out.println("name:"+p.name+",age:"+p.age);
			ois.close();
		}
		catch(Exception e)
		{
			e.printStackTrace();
		}
	}
}

class Person implements Serializable
{
	public String name;
	public int age;
	
	public Person(String name, int age)
	{
		this.name = name;
		this.age = age;
	}
}

name:Tom,age:13

GUI

组件、容器、布局管理器的关系

Panel

Frame

import java.awt.*;

public class Test extends java.applet.Applet{
	Choice testChoice;
	List testList;
	public void init()
	{
		testChoice = new Choice();
		testList = new List();
		for(int i=1; i<=3; i++){
			testChoice.addItem(String.valueOf(i));
			testList.addItem("Item "+i);
		}
		setLayout(new FlowLayout());
		add(testChoice);
		add(testList);
	}
	
	public static void main(String[] args)
	{
		new Test();
	}
}

布局管理器

c.setLayout(new XXXLayout());