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我正在Java to save objects state using Serializable通过以下代码尝试简单的程序，一旦我编写了这些对象，然后将它们设置为 null 但是when i try to get them back it gives me null values ，它不应该给我存储的值吗？ when i run this program answer is null null null，请查看并指导我，

游戏.java

public class Game implements Serializable{

    public Game() {
    }
    public int getSize() {
        return size;
    }

    public void setSize(int size) {
        this.size = size;
    }

    public String getType() {
        return Type;
    }

    public void setType(String type) {
        Type = type;
    }

    public String[] getName() {
        return name;
    }

    public void setName(String[] name) {
        this.name = name;
    }

    int  size; 
    String Type ; 
    String [] name; 

    public   Game (int thesize , String theType, String[] names )
    {

        this.size = thesize; 
        this.Type= theType;
        this.name = names; 
    }

}

游戏角色.java

public class GameCharacter extends Game {

    public GameCharacter(int i, String Type, String[] strings) {
        // TODO Auto-generated constructor stub
    }

    /**
     * @param args
     * @throws IOException 
     * @throws FileNotFoundException 
     */
    public static void main(String[] args) throws FileNotFoundException, IOException {
        Game g= new Game();

        GameCharacter GC1= new GameCharacter(1, "One " , new  String [] {"bow", "SWord", "Dust"});
        GameCharacter GC2 = new GameCharacter(2, "TWo", new String[] {"One ", "TWo ", "Three"});
        GameCharacter GC3= new GameCharacter(3, "Three", new String[] {"four ", "five ", "six"}); 

        ObjectOutputStream oos= new ObjectOutputStream (new FileOutputStream("Game.ser"));
        oos.writeObject(GC1);
        oos.writeObject(GC2);
        oos.writeObject(GC3);
        oos.close();          
        GC1= null;
        GC2= null; 
        GC3= null; 

        ObjectInputStream ois = new ObjectInputStream(new FileInputStream("Game.ser"));

        try
        {
            GameCharacter onerestore= (GameCharacter) ois.readObject();
            GameCharacter tworestore  = (GameCharacter) ois.readObject();
            GameCharacter threerestore= (GameCharacter) ois.readObject();
            System.out.print(onerestore.getName());
            System.out.println(tworestore.getType());
            System.out.println(threerestore.getName());
            //System.out.println("HEllo");

        } 
        catch (ClassNotFoundException e) 
        { 
            e.printStackTrace();
        }

}

4

3 回答 3

4

您的 GameCharacter 构造函数不会调用 Game 的构造函数，因此您传入的参数只是被忽略。尝试在原始对象上运行 println() 语句；你会得到相同的空值输出。修复它，序列化将正常工作。

于 2013-07-24T01:23:57.377 回答
1

是的，GameCharacter 类扩展了 Game。GameCharacter 中有一个构造函数。所以 GameCharacter onerestore= (GameCharacter) ois.readObject() 会调用定义在子类 GameCharacter 中的构造函数。但是看看这里

public GameCharacter(int i, String Type, String[] strings) {
        // TODO Auto-generated constructor stub
    }

是的，这个构造函数什么都不做。所以这些字段仍然为空；尝试如下改变构造函数，你可能会成功。

public GameCharacter(int i, String Type, String[] strings) {
        // TODO Auto-generated constructor stub
        super( i ,Type,strings);
    }
于 2013-07-24T01:41:06.310 回答
1

它正在序列化对象，但字段均为空。在 GameCharacter 的构造函数中，您需要调用正确的超级构造函数，否则默认调用的构造函数是没有参数的默认构造函数。

 public GameCharacter(int i, String Type, String[] strings) {
        // TODO Auto-generated constructor stub
       super(i, Type, strings); //you do not have this, hence your variables are null.
    }

附带说明，Type 是一个 java 类，请不要将其用作变量名。

于 2013-07-24T01:34:27.757 回答