Задача на линейный и бинарный поиск фамилии студента по первым буквам и целиком и по части телефонного номера

package student;
 
public class Student {
private String surname;
private String name;
private int year;
private long phonenumber;
public String getsurname() {
return surname;}
public void setsurname(String surname ){this.surname=surname;}
public String getsname() {
return name;}
public void setname(String name ){this.name=name;}
public int getyear() {
return year;}
public void setyear(int year ){this.year=year;}
public long getphonenumber() {
return phonenumber;}
public void setphonenumber(long phonenumber ){this.phonenumber=phonenumber;}
 
{Student mas[] = new Student[6];
for (int j = 0; j < 6; j++ )
mas[j] = new Student();}
}

import java.util.Arrays;
 
/**
 * Created by Sanan on 12.03.2015.
 */
public class Student {
 
    private String name;
    private String surname;
    private String birthday;
    private String phoneNumber;
 
 
    public String getName() {
        return name;
    }
 
    public void setName(String name) {
        this.name = name;
    }
 
    public String getSurname() {
        return surname;
    }
 
    public void setSurname(String surname) {
        this.surname = surname;
    }
 
    public String getBirthday() {
        return birthday;
    }
 
    public void setBirthday(String birthday) {
        this.birthday = birthday;
    }
 
    public String getPhoneNumber() {
        return phoneNumber;
    }
 
    public void setPhoneNumber(String phoneNumber) {
        this.phoneNumber = phoneNumber;
    }
 
 
    public Student(String name, String surname, String birthday, String phoneNumber) {
        this.name = name;
        this.surname = surname;
        this.birthday = birthday;
        this.phoneNumber = phoneNumber;
    }
 
    @Override
    public boolean equals(Object o) {
        if (this == o) return true;
        if (o == null || getClass() != o.getClass()) return false;
 
        Student student = (Student) o;
 
        if (birthday != null ? !birthday.equals(student.birthday) : student.birthday != null) return false;
        if (name != null ? !name.equals(student.name) : student.name != null) return false;
        if (phoneNumber != null ? !phoneNumber.equals(student.phoneNumber) : student.phoneNumber != null) return false;
        if (surname != null ? !surname.equals(student.surname) : student.surname != null) return false;
 
        return true;
    }
 
    @Override
    public int hashCode() {
        int result = name != null ? name.hashCode() : 0;
        result = 31 * result + (surname != null ? surname.hashCode() : 0);
        result = 31 * result + (birthday != null ? birthday.hashCode() : 0);
        result = 31 * result + (phoneNumber != null ? phoneNumber.hashCode() : 0);
        return result;
    }
 
    @Override
    public String toString() {
        return "Student{" +
                "name='" + name + '\'' +
                ", surname='" + surname + '\'' +
                ", birthday='" + birthday + '\'' +
                ", phoneNumber='" + phoneNumber + '\'' +
                '}';
    }
 
 
    public static int fullSurnameBinarySearch(Student[] st, String surname) {
 
        int low = 0;
        int hight = st.length - 1;
 
        while (low <= hight) {
            int med = (low + hight) / 2;
            if (surname.compareTo(st[med].getSurname()) > 0) {
                low = med + 1;
            }
            if (surname.compareTo(st[med].getSurname()) < 0) {
                hight = med - 1;
            } else return med;
        }
        return -1;
    }
 
    static int halfSurnameBinarySearch(Student[] st, String halfSurname) {
        int low = 0;
        int hight = st.length - 1;
 
        while (low <= hight) {
            int med = (low + hight) / 2;
            String S = st[med].getSurname();
            if (!S.startsWith(halfSurname)) {
                if (halfSurname.compareTo(S) > 0) {
                    low = med + 1;
                }
                if (halfSurname.compareTo(S) < 0) {
                    hight = med - 1;
                }
            }
            if (S.startsWith(halfSurname)) {
                return med;
            }
 
        }
        return -1;
    }
 
    static int fullSurnameLinearSearch(Student[] st, String surname) {
 
        for (int i = 0; i < st.length; i++) {
            if (st[i].getSurname().equals(surname)) {
                return i;
            }
        }
 
        return -1;
    }
 
    static int halfSurnameLinearSearch(Student[] st, String halfSurname) {
 
        for (int i = 0; i < st.length; i++) {
            if (st[i].getSurname().startsWith(halfSurname)) {
                return i;
            }
        }
 
        return -1;
    }
 
 
    static int halfPhoneNumberBinarySearch(Student[] st, String halfPhoneNumber) {
        int low = 0;
        int hight = st.length - 1;
 
        while (low <= hight) {
            int med = (low + hight) / 2;
            String S = st[med].getPhoneNumber();
            if (!S.startsWith(halfPhoneNumber)) {
                if (halfPhoneNumber.compareTo(S) > 0) {
                    low = med + 1;
                }
                if (halfPhoneNumber.compareTo(S) < 0) {
                    hight = med - 1;
                }
            }
            if (S.startsWith(halfPhoneNumber)) {
                return med;
            }
 
        }
        return -1;
    }
 
    static int halfPhoneNumberLinearSearch(Student[] st, String phoneNumber) {
 
        for (int i = 0; i < st.length; i++) {
            if (st[i].getPhoneNumber().startsWith(phoneNumber)) {
                return i;
            }
        }
 
        return -1;
    }
 
}

import java.util.Comparator;
 
/**
 * Created by Sanan on 12.03.2015.
 */
public class PhoneNumberComparator implements Comparator<Student> {
    @Override
    public int compare(Student o1, Student o2) {
        return o1.getPhoneNumber().compareTo(o2.getPhoneNumber());
    }
}

import java.util.Comparator;
 
/**
 * Created by Sanan on 12.03.2015.
 */
public class SurnameComparator implements Comparator<Student> {
 
    @Override
    public int compare(Student o1, Student o2) {
        return o1.getSurname().compareTo(o2.getSurname());
    }
}

public class Test {
    
 
    public static void main(String[] args) {
 
        Scanner s= new Scanner(System.in);
 
 
        Student alice = new Student("Alice","Cooper","12:05:1985","56329872");
        Student alan = new Student("Alan","Keth","23:07:1996","76543126");
 
        Student [] students = new Student[2];
        students[0]=alice;
        students[1]=alan;
 
        int n = Student.fullSurnameBinarySearch(students,"Cooper");
        System.out.println(n);
 
 
 
 
    }
}