Thiết kế lớp PhanSo (Phân số) gồm có:

        + 2 thuộc tính tử số và mẫu số thuộc kiểu nguyên

        + Các phương thức:

               - Phương thức khởi tạo.

               - Phương thức in phân số.

               - Phương thức nghịch đảo phân số.

               - Phương thức trả về giá trị thực của phân số

               - Hàm cộng, trừ, nhân, chia 2 phân số.

        + Phương thức main() sử dụng lớp PhanSo.

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import java.io.*;

public class PhanSo{

        protected int ts,ms;

        PhanSo(){

        }

        PhanSo(int t, int m){

               ts=t;

               ms=m;

        }

        static int nhapgt() throws IOException{            

               InputStreamReader isr = new InputStreamReader(System.in);

               BufferedReader br = new BufferedReader(isr);

               String str = br.readLine();

               return Integer.valueOf(str).intValue();

        }     

        PhanSo nhapps(int x) throws IOException{

               int tu,mau;

               System.out.println("Nhap phan so thu: " +x);

               System.out.print("Tu so: ");

               tu=nhapgt();

               System.out.print("Mau so: ");

               do{

                       mau=nhapgt();

                       if(mau==0) System.out.print("Nhap lai mau so");

               }while(mau==0);

               PhanSo ps = new PhanSo(tu,mau);

               return ps;

        }

        static int UCLN(int a, int b){

               while(a!=b){

                       if(a>b) a=a-b;

                       else b=b-a;

               }

               return a;

        }

        static PhanSo toigian(PhanSo ps){

               PhanSo phanso = new PhanSo();

               phanso.ts = ps.ts/UCLN(Math.abs(ps.ts),Math.abs(ps.ms));

               phanso.ms = ps.ms/UCLN(Math.abs(ps.ts),Math.abs(ps.ms));

               return phanso;

        }

        static PhanSo tong(PhanSo ps1, PhanSo ps2){

               PhanSo phanso = new PhanSo();

               phanso.ts= ps1.ts*ps2.ms + ps2.ts*ps1.ms;

               phanso.ms= ps1.ms*ps2.ms;

               if(phanso.ts!=0)

                       phanso=toigian(phanso);

               return phanso;

        }

        static PhanSo hieu(PhanSo ps1, PhanSo ps2){

               PhanSo phanso = new PhanSo();

               phanso.ts = ps1.ts*ps2.ms - ps2.ts*ps1.ms;

               phanso.ms = ps1.ms*ps2.ms;

               if(phanso.ts!=0)

                       phanso = toigian(phanso);

               return phanso;

        }

        static PhanSo tich(PhanSo ps1, PhanSo ps2){

               PhanSo phanso = new PhanSo();

               phanso.ts = ps1.ts*ps2.ts;

               phanso.ms = ps1.ms*ps2.ms;

               if(phanso.ts!=0)

                       phanso = toigian(phanso);

               return phanso;

        }

        static PhanSo thuong(PhanSo ps1,PhanSo ps2){

               PhanSo phanso=new PhanSo();

               phanso.ts = ps1.ts*ps2.ms;

               phanso.ms = ps1.ms*ps2.ts;

               if(phanso.ts!=0)

                       phanso=toigian(phanso);

               return phanso;

        }

        static void Hienthi(PhanSo ps){

               if(ps.ts==0 || ps.ms==1) System.out.print(ps.ts);

               else System.out.println(ps.ts+"/"+ps.ms);

        }

        public static void main(String args[]) throws IOException{

               PhanSo ps1 = new PhanSo();

               PhanSo ps2 = new PhanSo();

               ps1=ps1.nhapps(1);

               ps2=ps2.nhapps(2);

               if(ps1.ts!=0)

                       ps1=toigian(ps1);

               if(ps2.ts!=0)

                       ps2=toigian(ps2);

               System.out.println("Phan so 1 o dang toi gian: "); Hienthi(ps1);

               System.out.println();

               System.out.println("Phan so 2 o dang toi gian: "); Hienthi(ps2);

               System.out.println();

               System.out.print("Phan so tong: "); Hienthi(tong(ps1,ps2));

               System.out.print("Phan so hieu: "); Hienthi(hieu(ps1,ps2));

               System.out.print("Phan so tich: "); Hienthi(tich(ps1,ps2));

               if (ps2.ts!=0){

                       System.out.print("Phan so thuong(phan so 1/phan so 2): ");

                       Hienthi(thuong(ps1,ps2));

               }

               else System.out.print("Khong the thuc hien phep chia phan so 1/phan so 2 ");

                       System.out.println();

               if (ps1.ts!=0){

                       System.out.print("Phan so thuong(phan so 2/phan so 1): ");

                       Hienthi(thuong(ps2,ps1));

                }

               else System.out.print("Khong the thuc hien phep chia phan so 2/phan so 1 ");

                       System.out.println();

            }