package healthbuddy;
/**
*
* @author tpzap_000
*/
import java.io.*;
import com.thoughtworks.xstream.XStream;
import com.thoughtworks.xstream.io.xml.StaxDriver;
import com.thoughtworks.xstream.persistence.FilePersistenceStrategy;
import com.thoughtworks.xstream.persistence.PersistenceStrategy;
import com.thoughtworks.xstream.persistence.XmlArrayList;
import java.util.List;
import java.util.Scanner;
public class PersistentDataModelCntl implements Serializable{
private File theFile = new File("PDM.txt");
private XStream xstream = new XStream(new StaxDriver());
public static PersistentDataModelCntl thePDMCntl;
private PersistentDataModel thePDM;
public PersistentDataModelCntl(){
this.readPDMFile();
}
public static PersistentDataModelCntl getPDMCntl(){
if(thePDMCntl == null){
thePDMCntl = new PersistentDataModelCntl();
}
return thePDMCntl;
}
public void readPDMFile(){
try
{
System.out.println("in read file");
StringBuilder fileContents = new StringBuilder();
Scanner in = new Scanner(theFile);
String tempXML;
boolean test = in.hasNextLine();
System.out.println(test);
while(in.hasNextLine()){
fileContents.append(in.nextLine());
System.out.println("reading file contents");
}
tempXML = fileContents.toString();
thePDM = (PersistentDataModel)xstream.fromXML(tempXML);
}
//If the file does not exist, thePDM is instantiated to be a new, empty, PDM file. The file is then written to disk, and then read from disk
// using some recursive stuff. Also creates a test UserList so that I don't get a NullPointerException in the LoginCntl.
catch(FileNotFoundException ex){
System.out.println("FileNotFound");
thePDM = new PersistentDataModel();
thePDM.thePDMFoodList = new FoodList();
thePDM.thePDMMealList = new MealList();
thePDM.thePDMDietList = new DietList();
thePDM.thePDMDiet = new Diet();
//Creates new attributes if things are null.
this.writePDMFile();
this.readPDMFile();
System.out.println("FileNotFound Exception");
}
catch(IOException ex){
System.out.println("IO Exception");
ex.printStackTrace();
}
}
//Problem Code is here:
public void writePDMFile(){
try{
String xml = xstream.toXML(thePDM);
PrintWriter writer = new PrintWriter(theFile);
System.out.println(xml);
writer.println(xml);
}
catch(Exception ex){
System.out.println("There was a problem writing the file.");
}
}
public PersistentDataModel getPDM(){
return thePDM;
}
}
以上是我的代码。我目前有一个使用对象序列化的应用程序,它的数据持久性,但我在将其转换为XML的过程中。我正在使用Xstream库来创建XML,但是我在将其写入光盘时遇到了一些麻烦。 Xstream将XML作为String提供给我,然后我尝试使用PrintWriter将其写入文本文件。但是文本文件为空,但是我尝试写入的字符串不是。我对PrintWriter的理解是,你提供它应该写入的文件名,它试图写入该文件(如果它不存在则创建它),然后它应该将String的内容写入文件。
非常感谢任何帮助。不知道我哪里出错了。
答案 0 :(得分:0)
您需要致电PrintWriter::flush()
或PrintWriter::close()
。
答案 1 :(得分:0)
您需要添加
writer.close()
到代码的末尾。编写器仅在文件关闭时写入文件。
答案 2 :(得分:0)
在将xml写入文件
后尝试关闭PrintWriter答案 3 :(得分:-1)