编译器错误，我不明白

Question

我想让它在我运行 ComplexTest.class 的地方工作，然后在那个 class 它运行s Complex.class。我是 java 的新手，我不知道出了什么问题。不确定为什么编译器希望看到 .class 和它认为应该出现的分号。

主要class

public class ComplexTest 
{
    //private final double re;   // the real part
    //private final double im;   // the imaginary part
        public static void main(String[] paramArrayOfString)
    {
        CreateObjs();
        PrintHeader1();
        PrintHeader2();
        // invoke and Initialize a Complex object
             Complex Comp = new Complex(); // Invokes Complex constructor (pg 315)
             Comp.JunctionBox(CompA, CompB);
            // multiply.printQuestionResult();
        }  

    public static void CreateObjs()
    {
        Complex CompA = new Complex(9.5D, 7.7D);
            Complex CompB = new Complex(1.2D, 3.1D);
    }
    public static void PrintHeader1()
    {
        System.out.printf(" A complex number in the \n form (x, y) is equal to \n x + yi, where i is \n square root of -1.\n");
    }
    public static void PrintHeader2()
    {
        System.out.printf("\n *-Complex numbers calculations-*");
    }
}

第 2 class

/******************************************************************************
 *  Data type for complex numbers.
 *
 *  The data type is "imagmutable" so once you create and initialize
 *  a Complex object, you cannot change it. The "final" keyword
 *  when declaring re and imag enforces this rule, making it a
 *  compile-timage error to change the .re or .imag fields after
 *  they've been initialized.
 *
 *  % java Complex
 *  a            = 5.0 + 6.0i
 *  b            = -3.0 + 4.0i
 *  b + a        = 2.0 + 10.0i
 *  a - b        = 8.0 + 2.0i
 *  a * b        = -39.0 + 2.0i
 *  a / b        = 0.36 - 1.52i
******************************************************************************/
public class Complex {
    // Constants (final)
    private final double re;   // the real part
    private final double imag;   // the imaginaryinary part
    // Variables
    public double product;

    // create a new object with the given real and imaginaryinary parts
    public Complex(double real, double imaginary) {
        re = real;
        imag = imaginary;
    }

    // return a string representation of the invoking Complex object
    public String toString() {
        if (imag == 0) return "<" + re + ">";
        if (re == 0) return "<" + imag + ">";
        if (imag <  0) return "<" + re + " - " + (-imag) + ">";
        return "<" + re + ", " + imag + ">";// + "i";
    }

    // return a new Complex object whose value is (this + b)
    public Complex plus(Complex b) {
        Complex a = this;             // invoking object
        double real = a.re + b.re;
        double imaginary = a.imag + b.imag;
        return new Complex(real, imaginary);
    }

    // return a new Complex object whose value is (this - b)
    public Complex minus(Complex b) {
        Complex a = this;
        double real = a.re - b.re;
        double imaginary = a.imag - b.imag;
        return new Complex(real, imaginary);
    }

    // return a new Complex object whose value is (this * b)
    public Complex timages(Complex b) {
        Complex a = this;
        double real = a.re * b.re - a.imag * b.imag;
        double imaginary = a.re * b.imag + a.imag * b.re;
        return new Complex(real, imaginary);
    }

    // return a new Complex object whose value is the reciprocal of this
    public Complex reciprocal() {
        double scale = re*re + imag*imag;
        return new Complex(re / scale, -imag / scale);
    }

    // return the real or imaginaryinary part
    public double re() { return re; }
    public double imag() { return imag; }

    // return a / b
    public Complex divides(Complex b) {
        Complex a = this;
        return a.timages(b.reciprocal());
    }

    // sample client for testing
    public static void main(String[] args) {
        Complex a = new Complex(9.5, 7.7);
        Complex b = new Complex(1.2, 3.1);

        System.out.printf("a            = %s\n", a);
        System.out.println("b            = " + b);
        System.out.println("a + b        = " + a.plus(b));
        System.out.println("a - b        = " + a.minus(b));
        System.out.println("a * b        = " + a.timages(b));
        System.out.println("a / b        = " + a.divides(b));
    }
}

Compiler/Syntax 错误：

ComplexTest.java:15: error: constructor Complex in class Complex cannot be applied to given types;
                 Complex Comp = new Complex(); // Invokes Complex constructor (pg 315)
                                ^
  required: double,double
  found: no arguments
  reason: actual and formal argument lists differ in length
ComplexTest.java:16: error: cannot find symbol
                 Comp.JunctionBox(CompA, CompB);
                                  ^
  symbol:   variable CompA
  location: class ComplexTest
ComplexTest.java:16: error: cannot find symbol
                 Comp.JunctionBox(CompA, CompB);
                                         ^
  symbol:   variable CompB
  location: class ComplexTest
3 errors

EDIT1：修复了垃圾class，更新了错误代码块。我知道垃圾 class 是个问题。

EDIT2：我需要更多帮助，我在尝试修复已有的错误时犯了更多错误。

Answer 1

你有一个 "junk" class 声明把文件弄乱了。

public class JunctionBox() {

}

... 不是一个有效的 class 声明开头（括号不应该在那里），你应该只有一个 public class 声明 - 与class 命名为文件 - 在每个 Java 文件中。

删除 class 声明将使文件编译正确。

Answer 2

问题是由于连接了双精度和字符串，您必须首先以各种可能的方式将它们转换为字符串例如通过以下方式

改变 if (imag == 0) return "<" + re + ">" 到 if (imag == 0) return "<" + String.valueOf(re) + ">"

Answer 3

一些错误是： 1) 在 ComplexTest 的主要方法中调用您尚未定义的空 Constructor Complex()。 2) 在下一行代码中您使用了 CompA 和 CompB 对象，但您没有定义它们。 3) 在第二个文件中，您首先声明了 JunctionBox Class，但是您将一个主要方法方法放在同一文件的辅助 class 中。先更正上述错误和您质疑的更新。

编译器错误，我不明白

compiler errors, I do not underdstand

java

compiler-errors

syntax-error