Thread: How to change a string at indexOf

Hello,

I would like to change a string at the position of indexof. But I cant figure out how to do it. Should I use substring? in order to do it? And if yes how? Because I'm getting errors

 try {
            BufferedReader in = null;
            try {
                in = new BufferedReader(new FileReader(file));
            } catch (FileNotFoundException e) {
                e.printStackTrace();  //To change body of catch statement use File | Settings | File Templates.
            }
 
            System.out.println("Searching for :" + Changefield + " in file: " + file.getName());
            String line;
 
 
            while((line = in.readLine()) != null) {
                int index = line.indexOf(Changefield);
 
                 System.out.println(" Position of " + Changefield + "is at the position: " + index);
 
 
                System.out.println("Print"  + Changefield.substring(index));
    //            System.out.println("Old value " + Changefield + " new value : " + newValue);
 
            }

The Changefield and newValue are user input variables. Changefiled is a variable which exists in a file and newValue should replace the Changefield.

here are the errors:

In order to modify an event you can change one field at the time
write the name of the field and then write the new Value
14:00
16:00
Your choice was: 5Searching for :14:00 in file: 5.events.txt
Position of 14:00is at the position: 11
Exception in thread "main" java.lang.StringIndexOutOfBoundsException: String index out of range: -6
at java.lang.String.substring(String.java:1875)
at com.DistributedS.EventManager.modify(EventManager. java:292)
at com.DistributedS.EventManager.Start(EventManager.j ava:168)
at com.DistributedS.Main.main(Main.java:10)
at sun.reflect.NativeMethodAccessorImpl.invoke0(Nativ e Method)
at sun.reflect.NativeMethodAccessorImpl.invoke(Native MethodAccessorImpl.java:57)
at sun.reflect.DelegatingMethodAccessorImpl.invoke(De legatingMethodAccessorImpl.java:43)
at java.lang.reflect.Method.invoke(Method.java:606)
at com.intellij.rt.execution.application.AppMain.main (AppMain.java:120)

Process finished with exit code 1

Thank you very for your help