[英]TreeMap Map.Entry NotSerializableException in Java
我正在尝试将TreeMap序列化为文本文件,但无法使其正常工作。 我尝试打印/调试和阅读Javadocs。
我的Record和Table类都实现了可序列化,并且我还构建了一个自定义比较器,该比较器还为我的新TreeMap <>()实现了可序列化。
我相信我已将问题缩小为:
我的主要目标是通过在我writeObject()时正确序列化Map.Entry或TreeMap来消除NotSerializableException。
第二个问题是“ readObject0(未知来源)”是什么。 在其他与我的问题类似的情况下,有一个ObjectOutputStream:1356,我的来源不明。
我目前正在使用Java 8。
class Record实现了Serializable {
private String[] row;
类Table实现Serializable {
private TreeMap<String, Record> tm = new TreeMap<>(
new ReverseNaturalOrderComparator());
private String[] columns;
private int totalRecords;
[...]
[...]
[...]
void insertRecord( String key, Record r ) {
if( r.rowArrayLength() == numRowFields ) {
tm.put(key, r);
totalRecords++;
}
else {
System.out.println("Number of fields do not match. " +
"Please enter a record with " + numRowFields + " fields");
}
}
类文件{
File file = new File("KeyValues.txt");
void writeFile(Table t) throws IOException {
TreeMap<String, Record> ftm = t.getTreeMap();
FileOutputStream os = new FileOutputStream(file);
ObjectOutputStream oos = new ObjectOutputStream(os);
Set set = ftm.entrySet();
Iterator i = set.iterator();
while(i.hasNext()) {
Map.Entry<String, Record> keyValue = (Map.Entry<String, Record>)i.next();
if( !file.exists() ) { System.out.println("No such file exists"); }
else { oos.writeObject(keyValue); } // <---causing error
}
oos.close();
os.close();
}
类Files中的以下代码块导致错误:Iterator i = set.iterator(); while(i.hasNext()){
Map.Entry<String, Record> keyValue = (Map.Entry<String, Record>)i.next();
if( !file.exists() ) { System.out.println("No such file exists"); }
else { oos.writeObject(keyValue); } // <---causing error
}
oos.close();
os.close();
} main():
public static void main(String[] args) throws FileNotFoundException, IOException, ClassNotFoundException {
Table t = new Table();
Record test0 = new Record("We are the champions, my friend.");
Record test1 = new Record("hope this works, but might not");
Record test2 = new Record("sweet, yellow bananas");
Record test3 = new Record("and bad mistakes Ihave made afew");
Record test4 = new Record("Now using and printing a TreeMap<>");
Record test5 = new Record("Exploring Antarctica alongside the polar bears");
t.insertRecord("3",test3);
t.insertRecord("0",test0);
t.insertRecord("2",test2);
t.insertRecord("4",test4);
t.insertRecord("1",test1);
t.insertRecord("5",test5);
try { writeFile(t); } //this is giving me the error.
错误记录
java.io.NotSerializableException: java.util.TreeMap$Entry
Final filepath : ...KeyValues.txt
at java.io.ObjectOutputStream.writeObject0(Unknown Source)
at java.io.ObjectOutputStream.writeObject(Unknown Source)
at Files.writeFile(Files.java:52)
at Files.test(Files.java:87)
at Files.run(Files.java:64)
at Files.main(Files.java:62)
java.io.WriteAbortedException: writing aborted;
java.io.NotSerializableException: java.util.TreeMap$Entry
at java.io.ObjectInputStream.readObject0(Unknown Source)
at java.io.ObjectInputStream.readObject(Unknown Source)
at Table.readFile(Table.java:92)
at Files.test(Files.java:100)
at Files.run(Files.java:64)
at Files.main(Files.java:62)
Caused by: java.io.NotSerializableException: java.util.TreeMap$Entry
at java.io.ObjectOutputStream.writeObject0(Unknown Source)
at java.io.ObjectOutputStream.writeObject(Unknown Source)
at Files.writeFile(Files.java:33)
at Files.test(Files.java:66)
at Files.run(Files.java:48)
at Files.main(Files.java:46)
如果要序列化的类包含对象的引用,则描述这些对象的类也应实现Serializable(在这种情况下为Record类)。
编辑:您也可以尝试更改File file = new File("KeyValues.txt");
到String file = "KeyValues.txt";
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