用java构造实部与虚部_声明Complex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、比较相等等操作...

下面是一个简单的Java代码示例，用于构造实部和虚部，声明Complex类和实现一些常见的操作：

public class Complex {
    private double real; // 实部
    private double imaginary; // 虚部

    // 构造函数
    public Complex(double real, double imaginary) {
        this.real = real;
        this.imaginary = imaginary;
    }

    // 由字符串构造复数
    public static Complex fromString(String str) {
        String[] parts = str.split("\\+");
        double real = Double.parseDouble(parts[0]);
        double imaginary = Double.parseDouble(parts[1].replace("i", ""));
        return new Complex(real, imaginary);
    }

    // 复数加法
    public Complex add(Complex other) {
        return new Complex(real + other.real, imaginary + other.imaginary);
    }

    // 复数减法
    public Complex subtract(Complex other) {
        return new Complex(real - other.real, imaginary - other.imaginary);
    }

    // 字符串描述
    public String toString() {
        return real + "+" + imaginary + "i";
    }

    // 比较相等
    public boolean equals(Complex other) {
        return real == other.real && imaginary == other.imaginary;
    }
}

使用示例：

Complex c1 = new Complex(3, 4);
Complex c2 = Complex.fromString("2+5i");
Complex c3 = c1.add(c2);
Complex c4 = c1.subtract(c2);

System.out.println(c1.toString()); // 输出 "3.0+4.0i"
System.out.println(c2.toString()); // 输出 "2.0+5.0i"
System.out.println(c3.toString()); // 输出 "5.0+9.0i"
System.out.println(c4.toString()); // 输出 "1.0-1.0i"
System.out.println(c1.equals(c2)); // 输出 "false"