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Java实验课的学习笔记（二）类的简单使用

news 2025/9/13 7:02:11

本文章就讲的是很基础的类的使用
重点大概就是类的构造函数以及一些很基础的东西。

实验内容是些老生常谈的东西，Complex类，在当初学C++面向对象的时候也是这个样子展开的。
内容如以下：

public class Complex {float real;float imag;public Complex(){real = 0;imag = 0;}public Complex(float real, float imag){this.real = real;this.imag = imag;}public Complex add(float real){this.real += real;return this;}public Complex add(Complex complex){this.real += complex.real;this.imag += complex.imag;return this;}public Complex sub(float real){this.real -= real;return this;}public Complex sub(Complex complex){this.real -= complex.real;this.imag -= complex.imag;return this;}public Complex mul(float real){this.real *= real;this.imag *= real;return this;}public Complex mul(Complex complex){float TheReal = this.real;float TheImag = this.imag;this.real = TheReal * complex.real - TheImag*complex.imag;this.imag = TheReal * complex.imag + TheImag*complex.real;return this;}public String toString(){String str="";if(this.imag == 0){str += this.real;}else if(this.imag > 0 ){if(this.real==0){str += this.imag + "i";}else str += this.real + "+" + this.imag + "i";}else{if(this.real==0){str += this.imag + "i";}else str += this.real + "" + this.imag + "i";}return str;}}

这里也不得不说一丁点相关知识–重载 overload
如这里的：

	public Complex(){real = 0;imag = 0;}public Complex(float real, float imag){this.real = real;this.imag = imag;}public Complex add(float real){this.real += real;return this;}public Complex add(Complex complex){this.real += complex.real;this.imag += complex.imag;return this;}

这里的Complex()，Complex(float real, float imag)构造函数也就用了一些重载的知识。
所谓重载，就是函数名不变但是函数内部的参数变化，我们调用函数时通过函数里面的参数决定我们要调用哪个函数。
同理的，Complex add(float real),Complex add(Complex complex)也是如此，当add()的括号里面是一个float值的时候调用Complex add(float real)，括号里面是一个Complex对象的时候调用Complex add(Complex complex)。
我当时认为这不是理所当然的吗？其实不是的，这里是用到了重载（overload）的知识。
总代码：
在这里插入图片描述

包com.Class.Work3里的Complex类：

package com.Class.Work3;public class Complex {float real;float imag;public Complex(){real = 0;imag = 0;}public Complex(float real, float imag){this.real = real;this.imag = imag;}public Complex add(float real){this.real += real;return this;}public Complex add(Complex complex){this.real += complex.real;this.imag += complex.imag;return this;}public Complex sub(float real){this.real -= real;return this;}public Complex sub(Complex complex){this.real -= complex.real;this.imag -= complex.imag;return this;}public Complex mul(float real){this.real *= real;this.imag *= real;return this;}public Complex mul(Complex complex){float TheReal = this.real;float TheImag = this.imag;this.real = TheReal * complex.real - TheImag*complex.imag;this.imag = TheReal * complex.imag + TheImag*complex.real;return this;}public String toString(){String str="";if(this.imag == 0){str += this.real;}else if(this.imag > 0 ){if(this.real==0){str += this.imag + "i";}else str += this.real + "+" + this.imag + "i";}else{if(this.real==0){str += this.imag + "i";}else str += this.real + "" + this.imag + "i";}return str;}}

调用Complex类的TestWork3类：

import com.Class.Work3.Complex;public class TestWork3 {public static void main(String[] args) {Complex c = new Complex(1, 2);
//        c.add(5);
//        Complex w = new Complex(4,1);
//        c.sub(w);
//        Complex w2 = new Complex(1,2);
//        c.mul(w2);
//        c.mul(5);System.out.println(c);}
}