Java Collection Framework (TreeSet operation, automatic sorting of data, overriding CompareTo method)

/*treeset
* TreeSet automatically calls the element's CompareTo (Object obj) method after the data is stored and automatically sorts the data
* So the output data is sorted data
* Note: The return value of the CompareTo method is: Negative, 0, positive. Represent less than, equal to, greater than
* CompareTo (Object obj) method to override element for storing custom object elements
* When defining an element, you need to implement the comparable interface
* */

1 ImportJava.util.Iterator;2 ImportJava.util.TreeSet;3  Public classStudentcode {4     5      Public Static voidMain (String []args) {6         //defines a TreeSet object and assigns a value to the object that exists in Java7TreeSet ts1=NewTreeSet ();8Ts1.add ("java10");9Ts1.add ("Java01");TenTs1.add ("Java08"); OneTs1.add ("Java04"); A         //the value of the output object, which is the sorted data - System.out.println (TS1); -         //define a TreeSet object and assign a custom object theTreeSet ts2=NewTreeSet (); -Ts2.add (NewPerson ("LS", 11)); -Ts2.add (NewPerson ("ZS", 22)); -Ts2.add (NewPerson ("LS", 13)); +Ts2.add (NewPerson ("LS", 11)); -         //output object, also sorted data +          for(Iterator it=ts2.iterator (); It.hasnext ();) { APerson p=(person) it.next (); atSystem.out.println ("Name:" +p.getname () + ", Age:" +p.getage ()); -         } -     } - } - //custom data, need to implement comparable interface - classPersonImplementscomparable{ in     PrivateString name; -     Private intAge ; toPerson (String name,intAge ) { +          This. name=name; -          This. age=Age ; the     } *      PublicString GetName () { $         return  This. Name;Panax Notoginseng     } -      Public intGetage () { the         return  This. Age; +     } A     //override the CompareTo () method, the      Public intcompareTo (Object obj) { +         if(! (objinstanceofPerson )) -             Throw NewRuntimeException ("Not Person object"); $Person p =(person) obj; $         if( This.age>P.getage ()) { -             return1; -         } the         Else if( This.age<P.getage ()) { -             return-1;Wuyi}Else{ the             return  This. Name.compareto (P.getname ()); -         } Wu     } -}

1 /* TreeSet 2 *     TreeSet when the element is not comparable, or if the comparison is not required,  3  *         can make the TreeSet set a comparative feature.  4  *         define the comparator and pass the comparator as a parameter to the TreeSet collection 5  * The         comparator needs to implement the comparator interface 6 *     When the element is comparable and the comparator appears at the same time, the comparator will prevail.  7* /

8 ImportJava.util.Comparator;9 ImportJava.util.Iterator;Ten ImportJava.util.TreeSet; One  Public classStudentcode { A      -      Public Static voidMain (String []args) { -         //define the TreeSet object and pass in the comparer theTreeSet ts2=NewTreeSet (Newmycompareble ()); -Ts2.add (NewPerson ("LS", 11)); -Ts2.add (NewPerson ("ZS", 22)); -Ts2.add (NewPerson ("LS", 13)); +Ts2.add (NewPerson ("LS", 11)); -         //Output Object +          for(Iterator it=ts2.iterator (); It.hasnext ();) { APerson p=(person) it.next (); atSystem.out.println ("Name:" +p.getname () + ", Age:" +p.getage ()); -         } -     } - } - //define comparators--First order in name, age in second order - classMycomparebleImplementscomparator{ in     //implement the Compare method inside the comparator -      Public intCompare (Object o1,object O2) { toPerson p1=(person) O1; +Person p2=(person) O2; -         intnum=p1.getname (). CompareTo (P2.getname ()); the         if(num==0){ *             return NewInteger (P1.getage ()). CompareTo (NewInteger (P2.getage ())); $         }Panax Notoginseng         returnnum; -     } the } +  A //custom data, need to implement comparable interface--in the first order of age, the name is the second order the classPersonImplementscomparable{ +     PrivateString name; -     Private intAge ; $Person (String name,intAge ) { $          This. name=name; -          This. age=Age ; -     } the      PublicString GetName () { -         return  This. Name;Wuyi     } the      Public intGetage () { -         return  This. Age; Wu     } -     //override the CompareTo () method, About      Public intcompareTo (Object obj) { $         if(! (objinstanceofPerson )) -             Throw NewRuntimeException ("Not Person object"); -Person p =(person) obj; -         if( This.age>P.getage ()) { A             return1; +         } the         Else if( This.age<P.getage ()) { -             return-1; $}Else{ the             return  This. Name.compareto (P.getname ()); the         } the     } the}

Java Collection Framework (TreeSet operation, automatic sorting of data, overriding CompareTo method)