利用接口做参数,写个计算器,能完成加减乘除运算。
(1)定义一个接口Compute含有一个方法int computer(int n, int m)。
(2)设计四个类分别实现此接口,完成加减乘除运算。
(3)设计一个类UseCompute,类中含有方法:public void useCom(Compute com, int one, int two),此方法能够用传递过来的对象调用computer方法完成运算,并输出运算的结果。
(4)设计一个主类Test,调用UseCompute中的方法useCom来完成加减乘除运算。
interface IComput{
int computer(int n,int m);
}
class Plus implements IComput{
public int computer(int n,int m){
return m+n;
}
}
class Sub implements IComput{
public int computer(int n,int m){
return n-m;
}
}
class Mul implements IComput{
public int computer(int n,int m){
return n*m;
}
}
class Div implements IComput{
public int computer(int n,int m){
if(m!=0){
return n/m;
}
System.out.println("输入数值错误");
return 0;
}
}
class UseCompute{
public void useCom(IComput com, int m, int n){
System.out.println(com.computer(m,n));
}
}
public class Test6{
public static void main(String[] args) {
UseCompute uc=new UseCompute();
Plus a1=new Plus();
Sub a2=new Sub();
Mul a3=new Mul();
Div a4=new Div();
System.out.println("加法:");uc.useCom(a1,2,3);
System.out.println("减法:");uc.useCom(a2,2,3);
System.out.println("乘法:");uc.useCom(a3,1,2);
System.out.println("除法:");uc.useCom(a4,1,2);
}
}
工厂模式:
interface IComput{
int computer(int n,int m);
}
class Factory{
public static IComput getInstance(String className){
if("plus".equals(className)){
return new Plus();
}
if("sub".equals(className)){
return new Sub();
}
if("mul".equals(className)){
return new Mul();
}
if("div".equals(className)){
return new Div();
}
return null;
}
}
class Plus implements IComput{
public int computer(int n,int m){
return m+n;
}
}
class Sub implements IComput{
public int computer(int n,int m){
return n-m;
}
}
class Mul implements IComput{
public int computer(int n,int m){
return n*m;
}
}
class Div implements IComput{
public int computer(int n,int m){
if(m!=0){
return n/m;
}
System.out.println("输入数值错误");
return 0;
}
}
public class Test5{
public static void main(String[] args) {
if(args.length==0){
System.out.println("没有传递参数,程序结束");
System.exit(1);
}
IComput num=Factory.getInstance(args[0]);
int m = Integer.parseInt(args[1]);
int n = Integer.parseInt(args[2]);
System.out.println(num.computer(m,n));
}
}