如何调试错误（没有有效的构造函数）？

Posted 2023-03-30

【中文标题】如何调试错误（没有有效的构造函数）？

【英文标题】：How to debug Error(no valid constructor)?

【发布时间】：2017-03-28 20:57:08

【问题描述】：

在我使用 writeobject 之前没有错误，但它一直给我没有有效的构造函数错误，即使我创建了无参数构造函数和 UID，我的编码有什么问题？

这是控制台中的错误代码

java.io.InvalidClassException: AirSwift.Game_player$Player; no valid constructor
at java.io.ObjectStreamClass$ExceptionInfo.newInvalidClassException(Unknown Source)
at java.io.ObjectStreamClass.checkDeserialize(Unknown Source)
at java.io.ObjectInputStream.readOrdinaryObject(Unknown Source)
at java.io.ObjectInputStream.readObject0(Unknown Source)
at java.io.ObjectInputStream.readObject(Unknown Source)
at AirSwift.Game_stage.GameLoad(Game_stage.java:168)
at AirSwift.Game_main$7.actionPerformed(Game_main.java:168)
at javax.swing.AbstractButton.fireActionPerformed(Unknown Source)
at javax.swing.AbstractButton$Handler.actionPerformed(Unknown Source)
at javax.swing.DefaultButtonModel.fireActionPerformed(Unknown Source)
at javax.swing.DefaultButtonModel.setPressed(Unknown Source)
at javax.swing.plaf.basic.BasicButtonListener.mouseReleased(Unknown Source)
at java.awt.AWTEventMulticaster.mouseReleased(Unknown Source)
at java.awt.Component.processMouseEvent(Unknown Source)
at javax.swing.JComponent.processMouseEvent(Unknown Source)
at java.awt.Component.processEvent(Unknown Source)
at java.awt.Container.processEvent(Unknown Source)
at java.awt.Component.dispatchEventImpl(Unknown Source)
at java.awt.Container.dispatchEventImpl(Unknown Source)
at java.awt.Component.dispatchEvent(Unknown Source)
at java.awt.LightweightDispatcher.retargetMouseEvent(Unknown Source)
at java.awt.LightweightDispatcher.processMouseEvent(Unknown Source)
at java.awt.LightweightDispatcher.dispatchEvent(Unknown Source)
at java.awt.Container.dispatchEventImpl(Unknown Source)
at java.awt.Window.dispatchEventImpl(Unknown Source)
at java.awt.Component.dispatchEvent(Unknown Source)
at java.awt.EventQueue.dispatchEventImpl(Unknown Source)
at java.awt.EventQueue.access$500(Unknown Source)
at java.awt.EventQueue$3.run(Unknown Source)
at java.awt.EventQueue$3.run(Unknown Source)
at java.security.AccessController.doPrivileged(Native Method)
at java.security.ProtectionDomain$JavaSecurityAccessImpl.doIntersectionPrivilege(Unknown Source)
at java.security.ProtectionDomain$JavaSecurityAccessImpl.doIntersectionPrivilege(Unknown Source)
at java.awt.EventQueue$4.run(Unknown Source)
at java.awt.EventQueue$4.run(Unknown Source)
at java.security.AccessController.doPrivileged(Native Method)
at java.security.ProtectionDomain$JavaSecurityAccessImpl.doIntersectionPrivilege(Unknown Source)
at java.awt.EventQueue.dispatchEvent(Unknown Source)
at java.awt.EventDispatchThread.pumpOneEventForFilters(Unknown Source)
at java.awt.EventDispatchThread.pumpEventsForFilter(Unknown Source)
at java.awt.EventDispatchThread.pumpEventsForHierarchy(Unknown Source)
at java.awt.EventDispatchThread.pumpEvents(Unknown Source)
at java.awt.EventDispatchThread.pumpEvents(Unknown Source)
at java.awt.EventDispatchThread.run(Unknown Source)

这是一个实现 Externalizable 的类

public class Player implements Externalizable  
    /**
         * 
         */
        private static final long serialVersionUID = 1L;

        public int x, y, mode, attackspeed, speed, speedinattack, firecount, hp, mp, time;
        public boolean modechanging = false;                       
        public int modechangecount = 0;                            
        Image Player_img = new ImageIcon("Images/Player/Player_0.png").getImage();
        Image []Player_Mode_img;
        String sound_fire, sound_change;

        public Player()

        

        public Player(int hp)
            this.ChangeMode(1);
            this.hp = hp;
            this.mp = 100;
            this.x = 100;
            this.y = 600;
            this.time = 0;
        
        Image AnimeMode()                                                                                
            switch(mode)
            case 1: 
                if(modechangecount < 10) return Player_Mode_img[0];
                else if((9<modechangecount)&&(modechangecount<20)) return Player_Mode_img[1];
                else return Player_Mode_img[2];
            case 2:
                return Player_Mode_img[0];
            case 3:
                if(modechangecount < 10) return Player_Mode_img[0];
                else if((9<modechangecount)&&(modechangecount<20)) return Player_Mode_img[1];
                else return Player_Mode_img[2];
            default: return default_img;
            
        

        public void readExternal(ObjectInput in) throws IOException, ClassNotFoundException 
            // TODO Auto-generated method stub
            this.x = in.readInt(); this.y = in.readInt(); this.hp = in.readInt(); this.time = in.readInt();
        

        public void writeExternal(ObjectOutput out) throws IOException 
            // TODO Auto-generated method stub
            out.writeInt(this.x); out.writeInt(this.y); out.writeInt(this.hp); out.writeInt(this.time); 
        
    

【参考方案1】：

将默认构造函数也添加到AirSwift.Game_player 或将Player 声明为public static