How to sort on multiple fields in data class

i have class datajoindatasummary.  i want able sort lotnumber, datetime, absorbance and/or materialid fields.  it works lotnumber can't figure out how alter code allow sort other fields.  the datetime field nullable.  any responses appreciated.

thanks.

rob

using system;  using system.collections.generic;  using system.linq;  using system.text;  using system.threading.tasks;    namespace phoenix_fastscreen.dataaccess.entities  {      class datajoindatasummary : icomparable<datajoindatasummary>      {          public string materialid          {              get;              set;          }          public string lotnumber          {              get;              set;          }          public string panelformat          {              get;              set;          }          public int repeat          {              get;              set;          }          public decimal? absorbance          {              get;              set;          }          public datetime? datetime          {              get;              set;          }          public string welllocation          {              get;              set;          }          public string paneltype          {              get;              set;          }            public datajoindatasummary(string materialid, string lotnumber, string panelformat, int repeat, decimal? absorbance, datetime? datetime, string welllocation, string paneltype)          {              this.materialid = materialid;              this.lotnumber = lotnumber;              this.panelformat = panelformat;              this.repeat = repeat;              this.absorbance = absorbance;              this.datetime = datetime;              this.welllocation = welllocation;              this.paneltype = paneltype;          }            public int compareto(datajoindatasummary other)          {               return this.lotnumber.compareto(other.lotnumber);                      //    //return this.datetime.tostring().compareto(other.datetime.tostring());          }    		  	//i have code works sorting lotnumber, can't sort work datajoindatasummariescollectall.datetime field            datajoindatasummariescollectall.sort(delegate(datajoindatasummary datajoindatasummary1, datajoindatasummary datajoindatasummary2)          {              return datajoindatasummary1.lotnumber.compareto(datajoindatasummary2.lotnumber);          });    		

if objects in list<t>, can use linq sort objects property values.

http://www.tutorialsteacher.com/linq/linq-sorting-operators-orderby-orderbydescending

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