java对象转换的问题

[zs312979674]

package test;
import java.io.*;

public class SerializableTest {

	public static void main(String[] args){
		
		/*
		 * 
		 * 序列化
		 */
		FileOutputStream fos  = null;
		ObjectOutputStream oos = null;
		Person person = new Person("小明",32);
		person.setSpouse("春花");
		 
		try {
			
			fos = new FileOutputStream("d://text.person");
			oos = new ObjectOutputStream(fos);
			oos.writeObject(person);
			oos.close();
			fos.close();
		} catch (FileNotFoundException e) {
			// TODO Auto-generated catch block
			e.printStackTrace();
		} catch (IOException e) {
			// TODO Auto-generated catch block
			e.printStackTrace();
		}finally{
			
		}
		
		/*
		 * 
		 * 反序列化
		 */
		 Person p = null;  
		try {
			FileInputStream fis = new FileInputStream("d://test.person");
			ObjectInputStream ois = new ObjectInputStream(fis);
			Object obj = ois.readObject();
			
			if(obj instanceof Person)
				/*
				 *  //这里的变量p为什么要在上面Person p = null定义，
				 *  直接在这里Person p = (Person)obj要报错，是什么原因啊???
				 */
				 p  =  (Person)obj;  
			
		} catch (FileNotFoundException e) {
			// TODO Auto-generated catch block
			e.printStackTrace();
		} catch (IOException e) {
			// TODO Auto-generated catch block
			e.printStackTrace();
		} catch (ClassNotFoundException e) {
			// TODO Auto-generated catch block
			e.printStackTrace();
		}
		
	}

} 


/*
 * 可序列化的类
 */
class Person implements java.io.Serializable{
	
	
	/**
	 * 
	 */
	private static final long serialVersionUID = 1L;
	
	private String name; 
	private int age;
	private String spouse;
	public String getName() {
		return name;
	}
	public void setName(String name) {
		this.name = name;
	}
	public int getAge() {
		return age;
	}
	public void setAge(int age) {
		this.age = age;
	}
	public String getSpouse() {
		return spouse;
	}
	public void setSpouse(String spouse) {
		this.spouse = spouse;
	}
	
	
	public Person(){}
	
	public Person(String name,int age){}
}

[风尘中国]

你序列化的时候d:\\test.person 你拼错了，还有一些问题，给你贴出代码给你看下

import java.io.*;

public class SerializableTest {

    public static void main(String[] args){

        /*
        *
        * 序列化
        */
        FileOutputStream fos  = null;
        ObjectOutputStream oos = null;
        Person person = new Person("小明",32);
        person.setSpouse("春花");

        try {

            fos = new FileOutputStream("d://test.person");
            oos = new ObjectOutputStream(fos);
            oos.writeObject(person);
            oos.close();
            fos.close();
        } catch (FileNotFoundException e) {
            // TODO Auto-generated catch block
            e.printStackTrace();
        } catch (IOException e) {
            // TODO Auto-generated catch block
            e.printStackTrace();
        }finally{

        }

        /*
        *
        * 反序列化
        */
        Person p = null;
        try {
            FileInputStream fis = new FileInputStream("d://test.person");
            ObjectInputStream ois = new ObjectInputStream(fis);
            Object obj = ois.readObject();

            if(obj instanceof Person)
                /*
                 *  //这里的变量p为什么要在上面Person p = null定义，
                 *   Person p = null根本无所谓
                 *  直接在这里Person p = (Person)obj要报错，是什么原因啊???
                 *   直接这样转换也不会报错
                 */
                p  =  (Person)obj;
                System.out.println(p);

        } catch (FileNotFoundException e) {
            // TODO Auto-generated catch block
            e.printStackTrace();
        } catch (IOException e) {
            // TODO Auto-generated catch block
            e.printStackTrace();
        } catch (ClassNotFoundException e) {
            // TODO Auto-generated catch block
            e.printStackTrace();
        }

    }

}


/*
* 可序列化的类
*/
class Person implements java.io.Serializable{


    /**
     *
     */
    private static final long serialVersionUID = 1L;

    private String name;
    private int age;
    private String spouse;

    @Override
    public String toString() {
        return "Person{" +
                "name='" + name + '\'' +
                ", age=" + age +
                ", spouse='" + spouse + '\'' +
                '}';
    }

    public String getName() {
        return name;
    }
    public void setName(String name) {
        this.name = name;
    }
    public int getAge() {
        return age;
    }
    public void setAge(int age) {
        this.age = age;
    }
    public String getSpouse() {
        return spouse;
    }
    public void setSpouse(String spouse) {
        this.spouse = spouse;
    }


    public Person(){}

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

[原来缘来]

package test;
import java.io.*;

public class SerializableTest {

    public static void main(String[] args){
        
        /*
         * 
         * 序列化
         */
        FileOutputStream fos  = null;
        ObjectOutputStream oos = null;
        Person person = new Person("小明",32);
        person.setSpouse("春花");
         
        try {
            
            fos = new FileOutputStream("d:\\text.person");
            oos = new ObjectOutputStream(fos);
            oos.writeObject(person);
            oos.close();
            fos.close();
        } catch (FileNotFoundException e) {
            // TODO Auto-generated catch block
            e.printStackTrace();
        } catch (IOException e) {
            // TODO Auto-generated catch block
            e.printStackTrace();
        }finally{
            
        }
        
        /*
         * 
         * 反序列化
         */
           
        try {
            FileInputStream fis = new FileInputStream("d:\\text.person");
            ObjectInputStream ois = new ObjectInputStream(fis);
            Object obj = ois.readObject();
            
            Person p =(Person) obj;
                /*
                 *  //这里的变量p为什么要在上面Person p = null定义，
                 *  直接在这里Person p = (Person)obj要报错，是什么原因啊???
                 */
            System.out.println(p.getSpouse());
            
        } catch (FileNotFoundException e) {
            // TODO Auto-generated catch block
            e.printStackTrace();
        } catch (IOException e) {
            // TODO Auto-generated catch block
            e.printStackTrace();
        } catch (ClassNotFoundException e) {
            // TODO Auto-generated catch block
            e.printStackTrace();
        }
        
    }

} 


/*
 * 可序列化的类
 */
class Person implements java.io.Serializable{
    
    
    /**
     * 
     */
    private static final long serialVersionUID = 1L;
    
    private String name; 
    private int age;
    private String spouse;
    public String getName() {
        return name;
    }
    public void setName(String name) {
        this.name = name;
    }
    public int getAge() {
        return age;
    }
    public void setAge(int age) {
        this.age = age;
    }
    public String getSpouse() {
        return spouse;
    }
    public void setSpouse(String spouse) {
        this.spouse = spouse;
    }
    
    
    public Person(){}
    
    public Person(String name,int age){}
}

除了路径拼写错误,没有什么错误呀,楼主说得我也试了,没问题呀

[zhu6100441]

看错误信息就能看出来了，

FileInputStream fis = new FileInputStream("d:\\text.person");
            ObjectInputStream ois = new ObjectInputStream(fis);
            Object obj = ois.readObject();

由于路径写错，所以你的obj根本就读不出个东西来，所以你在转换的时候，也会报错。