没时间更优化了，（终极版）声明复数类，成员变量包括实部和虚部，成员方法包括实现由字符串构造复数、复数加法、减法，字符串描述、比较

实名感谢尚梦川大佬教会我正则表达式！！！！！！！！！！！！！！！！！！！！！！！！！！

输入的必须是正确答案，主要是尝试正则表达式。 看不懂的童邪慎用。优化也不是特别好，但是看懂了比较舒服。

有错误欢迎指正

import java.util.Scanner;

import java.util.regex.Matcher;

import java.util.regex.Pattern;

public class Complextest {

public float real,vir;

public static int count=0;

public static String Input()

{

Scanner in = new Scanner(System.in);

count++;

System.out.println("请输入第"+count+"个复数:");

String res= in.next();

return res;

}

public Complextest (String str)

{

if(str.equals("i")||str.equals("+i"))

{

this.real=0;

this.vir =1;

}

else if(str.equals("-i"))

{

this.real=0;

this.vir =-1;

}

else{

String a = "^([-+]?)(\\d+|\\d+\\.\\d+)$";//只有实部的匹配

String bi =   "^([-+]?)(\\d+|\\d+\\.\\d+)?(i+)$";//只虚部的匹配

String a_bi = "^([-+]?)(\\d+|\\d+\\.\\d+)([-+]+)(\\d+|\\d+\\.\\d+)(i+)$";//都有

String a_i =  "^([-+]?)(\\d+|\\d+\\.\\d+)([-+]+)(i+)$";

Pattern fora = Pattern.compile(a);

Pattern forbi = Pattern.compile(bi);

Pattern fora_bi = Pattern.compile(a_bi);

Pattern fora_i = Pattern.compile(a_i);

Matcher toa= fora.matcher(str);

Matcher tobi= forbi.matcher(str);

Matcher toa_bi= fora_bi.matcher(str);

Matcher toa_i= fora_i.matcher(str);

if(toa_i.find())//([-+]?)(\\\\d+|\\\\d+\\\\.\\\\d+)([-+]+)(i+)

{

this.real = Float.parseFloat(toa_i.group(1)+toa_i.group(2));

this.vir = 1;

if(toa_i.group(3).equals("-"))

{

this.vir*=-1;

}

}

if(toa.find())//只匹配实部

{

this.real = Float.parseFloat(toa.group(0));

this.vir = 0;

}else if(tobi.find())//只匹配虚部"([-+]?)(\\d+|\\d+\\.\\d+)(i+)";

{

this.real=0;

this.vir=Float.parseFloat(tobi.group(1)+tobi.group(2));

}

if(toa_bi.find())//([-+]?)(\\d+|\\d+\\.\\d+)([-+]+)(\\d+|\\d+\\.\\d+)(i+)

{

this.real = Float.parseFloat(toa_bi.group(1)+toa_bi.group(2));

if(toa_bi.group(4).length()==0)

{

this.vir=1;

if(toa_bi.group(3)=="+")

{

this.vir*=-1;

}

}else {

this.vir=Float.parseFloat(toa_bi.group(3)+toa_bi.group(4));

}

}

}

System.out.print("你输入的复数:");

sayResult(this.real,this.vir);

}

public void add(Complextest other)//加法

{

float sum_Real,sum_Vir;

sum_Real=this.real+other.real;

sum_Vir=this.vir+other.vir;

System.out.print("和:");

sayResult(sum_Real,sum_Vir);

}

public void lenth(Complextest other)//长度

{

float x_len,y_len;

x_len=this.real-other.real;

y_len=this.vir-other.vir;

System.out.println("长度是"+String.format("%.2f", Math.sqrt(x_len*x_len+y_len*y_len)));

}

public boolean equls(Complextest other)

{

System.out.print("是否相等:");

return this==other||Math.abs(this.real-other.real)<0.001&&Math.abs(this.vir-other.vir)<0.001;

}

public void diff(Complextest other)//减法

{

float diff_Real,diff_Vir;

diff_Real=this.real-other.real;

diff_Vir=this.vir-other.vir;

System.out.print("差:");

sayResult(diff_Real,diff_Vir);

}

public void sayResult(float Real_,float Vir_)

{

StringBuffer put = new StringBuffer();

String str=String.valueOf(Real_);

if(Real_!=0)//实部存在

{

put.append(str);

if(Vir_!=0)//等于0就不管

{

if(Vir_>0)

{

if(Vir_==1)//虚部为1

{

put.append("+i");

}else {

put.append("+"+Vir_+"i");

}

} else if(Vir_<0)

{

if(Vir_==-1)//虚部为-1

{

put.append("-i");

}else {

put.append(Vir_+"i");

}

}

}

}else//不存在实部

{

if(Vir_!=0)//只有虚部

{

if(Vir_==-1)

{

put.append("-i");

}else if(Vir_==1)

{

put.append("i");

}else

{

put.append(Vir_+"i");

}

}else//虚部都没有

{

put.append("0");

}

}

System.out.println(put);

}

public static void main(String[] args) {

String str;

str = Input(); 

Complextest first = new Complextest(str); 

    str = Input(); 

    Complextest second = new Complextest(str);

first.add(second);

first.diff(second);

first.lenth(second);

System.out.println(first.equls(second));

}

}