java - Why isn't Collections.binarySearch outputting consistently -

so trying write program school. point of make list of cds user has in collection. program needs show list of cds both in original order (cds) , in alphabetically sorted order (cdss). information has stored in array list. have make used able add , remove programs.

when when enter song "beatles - abbey road", assumed output 1 collections.binarysearch, instead outputs -1 2 times outputs 1's. seems work other songs though.

i cannot remove song creates error

thanks help

private void buttoninitializeactionperformed(java.awt.event.actionevent evt) {                                                      //this original songs added(when initialize button pressed)     collections.addall(cds, "metric - fantasies", "beatles - abbey road", "pearl jam - ten", "doors - alive", "the rolling stones - gimme shelter");     collections.addall(cdss, "metric - fantasies", "beatles - abbey road", "pearl jam - ten", "doors - alive", "the rolling stones - gimme shelter");     //once initialize button pressed other buttong able enabled     buttondisplay.setenabled(true);     buttonremove.setenabled(true);     buttonadd.setenabled(true);     buttoninitialize.setenabled(false); }                                                  private void buttondisplayactionperformed(java.awt.event.actionevent evt) {                                                   outputsonglist.settext("original order");      int condition = 0;     //condition value thatis increased 1 every time each of these while loops ran.      //from 1 many objects there in either cds or cdss array list     //the s in cdss stands sorted     while(condition < cds.size()){         outputsonglist.settext(outputsonglist.gettext() + "\n" + cds.get(condition));//writing contents of array list text area         condition++;     }     outputsonglist.settext(outputsonglist.gettext() + "\n\n\nsorted order");      collections.sort(cdss, string.case_insensitive_order);//this sorts cdss array in alphabetical order      condition = 0;      while(condition < cdss.size()){         outputsonglist.settext(outputsonglist.gettext() + "\n" + cdss.get(condition));//the same previous while loop         condition++;     }     buttondisplay.setenabled(false);//disables display button user knows information displayed }                                               private void buttonaddactionperformed(java.awt.event.actionevent evt) {                                               string inputsong = entersong.gettext();//getting string user typed entersong text field      if(collections.binarysearch(cds, inputsong) < 0){//this checks if inputted song in arraylist         cds.add(inputsong);                             //if is, outputted number 1...i thought         cdss.add(inputsong);                            //if isn't numer less 0         collections.sort(cdss);              //this if statement run if inputted song isn't in arrays         buttondisplay.setenabled(true);                      } }                                           private void buttonremoveactionperformed(java.awt.event.actionevent evt) {                                                  string inputsong = entersong.gettext();      if(collections.binarysearch(cds, inputsong) > -1){//if inputted song in array line run         cds.remove(collections.binarysearch(cds, inputsong));         cdss.remove(collections.binarysearch(cds, inputsong));         buttonremove.setenabled(false);         buttondisplay.setenabled(true);     } }  

from you've said, cds not sorted in particular order. collections.binarysearch states in javadoc works if list receives sorted.

instead of using collections.binarysearch, have use cds.indexof(inputsong) , accept linear search.