validation - Java Check if a new date range falls/crossovers between other date ranges -

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• determine whether 2 date ranges overlap 32 answers

i need determine if date range within/cross on other date ranges. eg:

new start date 1: 12/01/2015 (mm/dd/yyyy) new start date 2: 03/01/2016 --> throw error message 

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new start date 1: 12/01/2016 new start date 2: 12/01/2017 --> throw error message 

existing date ranges:

existing 1: 01/01/2016 - 05/31/2016 existing 2: 06/05/2017 - 10/31/2017 

i should generate error message if new dates fall/crossover existing dates. here existing code (not working expected):

for (period p : periodlist) {     if (!(newperiodstartdate.after(p.getexistingperiodstartdate()))          && !(newperiodstartdate.before(p.getexistingperiodenddate()))) {             message = "the period falls between existing period: "+p.periodname();             break;     }     if (newperiodenddate.after(p.getexistingperiodstartdate())          && newperiodenddate.before(p.getexistingperiodenddate())) {          if (message == null) {             message = " period falls between existing period: "+p.getperiodname();          }             break;     } } 

edit

updated code (still not working). missing:

if (!(newperiodstartdate.gettime() <= p.getexistingperiodenddate().gettime())                                         && (newperiodenddate.gettime() <= p.getexistingperiodstartdate().gettime())) {    ... } 

edit 2:

this duplicate question, answer question did not fix issue. blog post (http://baodad.blogspot.com/2014/06/date-range-overlap.html) helped me fix.

finally, worked:

 boolean isoverlapped(date newstartdate, date newenddate, date existingstartdate, date existingenddate) throws nullpointerexception{             if (!((newenddate.gettime() <= existingstartdate.gettime())                 || (newstartdate.gettime() >= existingenddate.gettime()))) {                 return true;             } else {                 return false;             }         }