相关疑难解决方法(0)

我试着写入txt文件.
但是丢失已经存储在文件中的数据.

但我的问题是,当我把字符串放在txt文件中时,新字符串会覆盖我之前放置的旧字符串.

我的代码是:

public void addWorker(Worker worker){
        workers.put(worker.getId(), worker);

    }

    public void printWorker (String id){
    Worker work = (Worker) workers.get( id );

    if (work == null) {
        System.out.println("Worker NOT found");
    } 

    else {
         work.printText();
     }
    }
       public void printWorkers() {
           if (workers.size() == 0) {
               System.out.println("No workres");
                return;
           }

           Collection<Worker> c = workers.values();
           Iterator<Worker> itr = c.iterator();
           System.out.println("Workers in division "+dName+ ":");
           while (itr.hasNext()) {
                  Worker wo = itr.next(); 
                  wo.printText();
           }
       }

       public void writeToFile(){
           PrintWriter pw = null; …

我用谷歌搜索了一段时间,但似乎无法找到它,它应该很容易.我想将CR附加到我用Transformer创建的XML文件的末尾.有没有办法做到这一点>

我尝试了以下但这导致了一个空白文件？

Transformer xformer = TransformerFactory.newInstance().newTransformer();
xformer.setOutputProperty(OutputKeys.DOCTYPE_SYSTEM, "file:///ReportWiz.dtd");
xformer.transform(source, result);
OutputStream writer = new FileOutputStream(file);
Byte b = '\n';
writer.write(b);
writer.close();