import java.util.*;

class TestCollectionsSort

{

public static void main(String[] args)

{

List<Person> school = new ArrayList<>();

school.add( new Person("Li",23));

school.add( new Person("Wang",28));

school.add( new Person("Zhang",21));

school.add( new Person("Tang",19));

school.add( new Person("Chen",22));

school.add( new Person("Zhao",22));

System.out.println( school );

Collections.sort( school, new PersonComparator() );

System.out.println( school );

int index = Collections.binarySearch(

school, new Person("Li",23), new PersonComparator() );

if( index >=0 )

System.out.println( "Found:" + school.get( index ));

else

System.out.println( "Not Found!" );

}

}

class Person

{

String name;

int age;

public Person( String name, int age){

this.name=name;

this.age=age;

}

@Override

public String toString(){

return name+":"+age;

}

}

class PersonComparator implements Comparator

{

public int compare( Object obj1, Object obj2 ){

Person p1 = (Person)obj1;

Person p2 = (Person)obj2;

if( p1.age > p2.age ) return 1;

else if(p1.age<p2.age) return -1;

return p1.name.compareTo( p2.name );

}

}