不能序列化我的Java类

cant serialize my class Java

似乎我无法序列化名为"ban"的类：

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class Ban implements Serializable{
/**
*
*/
transient Date start;
transient Date end;
String explination;
String from;
public Ban(Date s, Date e, String ex, String f){
start = s;
end = e;
explination = ex;
from = f;
}
}

当我尝试用ObjectOutputStream打印这个时，它会给我一个错误…你能帮我把这门课连载一下吗？顺便问一下：瞬变是什么意思？

好吧，这是布基特，但这应该做到：

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[SEVERE] java.io.NotSerializableException: me.bubblegumsoldier.Ban.Main
2013-04-03 19:30:30 [SEVERE] at java.io.ObjectOutputStream.writeObject0(Unknown Source)
2013-04-03 19:30:30 [SEVERE] at java.io.ObjectOutputStream.defaultWriteFields(Unknown Source)
2013-04-03 19:30:30 [SEVERE] at java.io.ObjectOutputStream.writeSerialData(Unknown Source)
2013-04-03 19:30:30 [SEVERE] at java.io.ObjectOutputStream.writeOrdinaryObject(Unknown Source)
2013-04-03 19:30:30 [SEVERE] at java.io.ObjectOutputStream.writeObject0(Unknown Source)
2013-04-03 19:30:30 [SEVERE] at java.io.ObjectOutputStream.writeObject(Unknown Source)
2013-04-03 19:30:30 [SEVERE] at java.util.HashMap.writeObject(Unknown Source)
2013-04-03 19:30:30 [SEVERE] at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
2013-04-03 19:30:30 [SEVERE] at sun.reflect.NativeMethodAccessorImpl.invoke(Unknown Source)
2013-04-03 19:30:30 [SEVERE] at sun.reflect.DelegatingMethodAccessorImpl.invoke(Unknown Source)
2013-04-03 19:30:30 [SEVERE] at java.lang.reflect.Method.invoke(Unknown Source)
2013-04-03 19:30:30 [SEVERE] at java.io.ObjectStreamClass.invokeWriteObject(Unknown Source)
2013-04-03 19:30:30 [SEVERE] at java.io.ObjectOutputStream.writeSerialData(Unknown Source)
2013-04-03 19:30:30 [SEVERE] at java.io.ObjectOutputStream.writeOrdinaryObject(Unknown Source)
2013-04-03 19:30:30 [SEVERE] at java.io.ObjectOutputStream.writeObject0(Unknown Source)
2013-04-03 19:30:30 [SEVERE] at java.io.ObjectOutputStream.writeObject(Unknown Source)
2013-04-03 19:30:30 [SEVERE] at me.bubblegumsoldier.Ban.Main.save(Main.java:113)
2013-04-03 19:30:30 [SEVERE] at me.bubblegumsoldier.Ban.Main.onDisable(Main.java:247)
2013-04-03 19:30:30 [SEVERE] at org.bukkit.plugin.java.JavaPlugin.setEnabled(JavaPlugin.java:219)
2013-04-03 19:30:30 [SEVERE] at org.bukkit.plugin.java.JavaPluginLoader.disablePlugin(JavaPluginLoader.java:481)
2013-04-03 19:30:30 [SEVERE] at org.bukkit.plugin.SimplePluginManager.disablePlugin(SimplePluginManager.java:400)
2013-04-03 19:30:30 [SEVERE] at org.bukkit.plugin.SimplePluginManager.disablePlugins(SimplePluginManager.java:393)
2013-04-03 19:30:30 [SEVERE] at org.bukkit.craftbukkit.v1_5_R2.CraftServer.disablePlugins(CraftServer.java:277)
2013-04-03 19:30:30 [SEVERE] at net.minecraft.server.v1_5_R2.MinecraftServer.stop(MinecraftServer.java:331)
2013-04-03 19:30:30 [SEVERE] at net.minecraft.server.v1_5_R2.MinecraftServer.run(MinecraftServer.java:438)
2013-04-03 19:30:30 [SEVERE] at net.minecraft.server.v1_5_R2.ThreadServerApplication.run(SourceFile:573)

号

我的保存代码如下：

变量：

1	public static HashMap<String, Ban> banned = new HashMap<String, Ban>();

保存部分：

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ObjectOutputStream oos = new ObjectOutputStream(new FileOutputStream(file));
oos.writeObject(banned);
oos.flush();
oos.close();

。

相关讨论

似乎您已经将ban定义为另一个名为main的类的非静态内部类：

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public class Main {

class Ban {
...
}
}

这意味着每个BAN实例都有一个对其外部主实例的隐式引用。以上代码与以下代码类似：

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public class Main {
static class Ban {
private Main main;
}
}

。

或公共类主{}

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class Ban {
private Main main;
}

所以当您序列化一个BAN时，您也在序列化这个隐式实例，它是不可序列化的，因此是异常的。

使ban成为顶级类或静态内部类。

发布的禁令类没有任何问题。可能错误是由类产生的，其中包含一个不可序列化的主字段变量。但问题中发布的代码可以序列化；我们可以运行以下代码：

公共类禁止实现可序列化{

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transient Date start;
transient Date end;
String explination;
String from;

public Ban(Date s, Date e, String ex, String f) {
start = s;
end = e;
explination = ex;
from = f;
}

public String toString() {
return"Ban{" +"start=" + start +", end=" + end +", explination=" + explination +", from=" + from + '}';
}

public static void main(String[] args) throws IOException, ClassNotFoundException {
Ban x = new Ban(new Date(), new Date(),"Transient means do not serialize.","Thorn");
File f = new File("test.out");
ObjectOutputStream out = new ObjectOutputStream(new FileOutputStream(f));
out.writeObject(x);
out.close();

ObjectInputStream in = new ObjectInputStream(new FileInputStream(f));
Ban fromFile = (Ban) in.readObject();
System.out.println(fromFile);
in.close();
}

}

产生的输出为：

1	Ban{start=null, end=null, explination=Transient means do not serialize., from=Thorn}

号

注意，输出的两个日期都为空，即使我给了它们值。未序列化临时值。