Question

编译器告诉我这个类Position不可序列化。我不确定为什么我已经实现了serializble接口

private class Position 
    extends CommandParent implements CommandInterface, Serializable {

    public Position(){
        xVal = 10000;
        yVal = 10000;
        zVal = 10000;
        iVal = null;
        jVal = null;
    }

    @Override
    public CommandType getCommandType(){return CommandType.POSITION;}
    @Override
    public String getKey(){return KEY_POSITION;}

}

这是界面

public interface CommandInterface {

    CommandType getCommandType();
    String getKey();
}

和超级

public class CommandParent implements Serializable {

// Data
protected Number xVal;
protected Number yVal;
protected Number zVal;
protected Number iVal;
protected Number jVal;

// Getters
protected Number getXcomponent(){ return xVal;}
protected Number getYcomponent(){ return yVal;}
protected Number getZcomponent(){ return zVal;}
protected Number getIcomponent(){ return iVal;}
protected Number getJcomponent(){ return jVal;}

// Setters
public void setXcomponent(Number x) { xVal = x; }
public void setYcomponent(Number y) { yVal = y; }
public void setZcomponent(Number z) { zVal = z; }
public void setIcomponent(Number i) { iVal = i; }
public void setJcomponent(Number j) { jVal = j; }

boolean xEnable = true;
boolean yEnable = true;
boolean zEnable = true;

}

这是我的序列化算法;我将类Position作为接口类型传递给save方法。

private void save(CommandInterface command) {

    Log.v(TAG,"save");
    Log.v(TAG,"saving : "+command.getKey());

    try {

        // Create a new file with an ObjectOutputStream.
        File file = new File(mCtx.getFilesDir(), command.getKey());

        ObjectOutputStream outputStream = new ObjectOutputStream(new FileOutputStream(file));

        // Write something in the file.
        outputStream.writeObject(command); // <=== Throws the error

        // Close and flush the stream.
        outputStream.flush();
        outputStream.close();

    } catch (FileNotFoundException e) {
        Log.d("Exception: ", Log.getStackTraceString(e));
    } catch (IOException e) {
        Log.d("Exception: ", Log.getStackTraceString(e));
    }
}

此行的错误结果

// Write something in the file.
outputStream.writeObject(command); // <=== Throws the error

这是堆栈跟踪

Java.io.NotSerializableException: com.example.michael.gloevo1.ActivityGloEvoPage.GloEvoPageActivity
     at java.io.ObjectOutputStream.writeNewObject(ObjectOutputStream.java:1344)
     at java.io.ObjectOutputStream.writeObjectInternal(ObjectOutputStream.java:1651)
     at java.io.ObjectOutputStream.writeObject(ObjectOutputStream.java:1497)
     at java.io.ObjectOutputStream.writeObject(ObjectOutputStream.java:1461)
     at java.io.ObjectOutputStream.writeFieldValues(ObjectOutputStream.java:959)
     at java.io.ObjectOutputStream.defaultWriteObject(ObjectOutputStream.java:360)
     at java.io.ObjectOutputStream.writeHierarchy(ObjectOutputStream.java:1054)
     at java.io.ObjectOutputStream.writeNewObject(ObjectOutputStream.java:1384)
     at java.io.ObjectOutputStream.writeObjectInternal(ObjectOutputStream.java:1651)
     at java.io.ObjectOutputStream.writeObject(ObjectOutputStream.java:1497)
     at java.io.ObjectOutputStream.writeObject(ObjectOutputStream.java:1461)
     at java.io.ObjectOutputStream.writeFieldValues(ObjectOutputStream.java:959)
     at java.io.ObjectOutputStream.defaultWriteObject(ObjectOutputStream.java:360)
     at java.io.ObjectOutputStream.writeHierarchy(ObjectOutputStream.java:1054)
     at java.io.ObjectOutputStream.writeNewObject(ObjectOutputStream.java:1384)
     at java.io.ObjectOutputStream.writeObjectInternal(ObjectOutputStream.java:1651)
     at java.io.ObjectOutputStream.writeObject(ObjectOutputStream.java:1497)
     at java.io.ObjectOutputStream.writeObject(ObjectOutputStream.java:1461)
     at com.example.michael.gloevo1.ActivityGloEvoPage.CommandManager.save(CommandManager.java:252)
     at com.example.michael.gloevo1.ActivityGloEvoPage.CommandManager.saveCurrentCommand(CommandManager.java:66)
     at com.example.michael.gloevo1.ActivityGloEvoPage.GloEvoPageActivity.onPause(GloEvoPageActivity.java:123)
     at android.app.Activity.performPause(Activity.java:6386)
     at android.app.Instrumentation.callActivityOnPause(Instrumentation.java:1311)
     at android.app.ActivityThread.performPauseActivity(ActivityThread.java:3385)
     at android.app.ActivityThread.performPauseActivity(ActivityThread.java:3358)
     at android.app.ActivityThread.handlePauseActivity(ActivityThread.java:3333)
     at android.app.ActivityThread.-wrap13(ActivityThread.java)
     at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1358)
     at android.os.Handler.dispatchMessage(Handler.java:102)
     at android.os.Looper.loop(Looper.java:148)
     at android.app.ActivityThread.main(ActivityThread.java:5451)
     at java.lang.reflect.Method.invoke(Native Method)
     at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:726)
     at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:616)

Answer 1

编译器告诉我这个类Position不可序列化。

不，不是。 JVM 在运行时通过异常告诉您：

Java.io.NotSerializableException: com.example.michael.gloevo1.ActivityGloEvoPage.GloEvoPageActivity

这是因为Position是一个内部类，例如GloEvoPageActivity，这意味着Position实例拥有对封闭GloEvoPageActivity实例的引用，不可序列化。

使Position成为静态或顶级类，并解决出现的任何编译错误。

Answer 2

我的解决方案是在写入对象

之前使GloEvoPageActivity传入的全局上下文变量无效

private void save(CommandInterface command) {

    Log.v(TAG,"save");
    Log.v(TAG,"saving : "+command.getKey());
    Log.v(TAG,"command is an instance of position : "+String.valueOf(command instanceof Position));
    Log.v(TAG,"command is an instance of position : "+String.valueOf(command instanceof GloEvoPageActivity));

    try {

        // Create a new file with an ObjectOutputStream.
        File file = new File(mCtx.getFilesDir(), command.getKey());

        ObjectOutputStream outputStream = new ObjectOutputStream(new FileOutputStream(file));

        Context temp = mCtx;
        mCtx = null;

        // Write something in the file.
        outputStream.writeObject(command);

        mCtx = temp;

        // Close and flush the stream.
        outputStream.flush();
        outputStream.close();

    } catch (FileNotFoundException e) {
        Log.d("Exception: ", Log.getStackTraceString(e));
    } catch (IOException e) {
        Log.d("Exception: ", Log.getStackTraceString(e));
    }
}

实现Serializable接口但类对象仍然不可序列化

2 个答案: