我想知道如何从我的随机访问文件中删除一条记录。
这是我添加到我的 RAF 的方法，但不确定如何删除它：X
public void addNewStudent(String name, String formClass, String emailAddress, String country1, String country2, String universityChoice)
{
try
{
RandomAccessFile theFile = new RandomAccessFile("studentData.dat","rw");
long records = (theFile.length()+299)/300; //Number of records
if(theFile.length()>0) //Check if the file is empty or not
{
for(long x=0;x<records;x++)
{
theFile.seek(x*300);
String currentName = theFile.readUTF();
if(name.equalsIgnoreCase(currentName)) //Check if student exists in database
{
output("This student exist already"); //Output this if exists
}
else // or else write a new record
{
theFile.seek(records*300);
theFile.writeUTF(name); //Write student name
theFile.seek((records*300)+50);
theFile.writeUTF(formClass); //Writes students' form class
theFile.seek((records*300)+60);
theFile.writeUTF(emailAddress); //Writes students' email
theFile.seek((records*300)+100);
theFile.writeUTF(country1); //Writes students' country choice #1
theFile.seek((records*300)+140);
theFile.writeUTF(country2); //Writes students' country choice #2
theFile.seek((records*300)+180);
theFile.writeUTF(universityChoice); //Writes students' university choices
students.add(name,formClass,emailAddress,country1,country2,universityChoice);
}
}
}
else //If the file isn't empty, then just write
{
theFile.seek(records*300);
theFile.writeUTF(name); //Write student name
theFile.seek((records*300)+50);
theFile.writeUTF(formClass); //Writes students' form class
theFile.seek((records*300)+60);
theFile.writeUTF(emailAddress); //Writes students' email
theFile.seek((records*300)+100);
theFile.writeUTF(country1); //Writes students' country choice #1
theFile.seek((records*300)+140);
theFile.writeUTF(country2); //Writes students' country choice #2
theFile.seek((records*300)+180);
theFile.writeUTF(universityChoice); //Writes students' university choices
students.add(name,formClass,emailAddress,country1,country2,universityChoice);
}
}
catch(IOException e)
{
output("Error while adding new student");
}
}