Question

我正在用java编写程序我必须创建一个类（InvoiceTest），它将包含main和第二个类（Invoice）。当我运行主InvoiceTest类时，它应该在Invoice类中显示消息。我一直收到错误

Exception in thread "main" java.lang.ExceptionInInitializerError
    at InvoiceTest.main(InvoiceTest.java:4)
Caused by: java.lang.RuntimeException: Uncompilable source code - constructor Invoice() is already defined in class Invoice
    at Invoice.<clinit>(Invoice.java:20)
    ... 1 more

我不知道该怎么做，请让我知道我做错了什么以及如何解决它的任何建议。感谢

public class InvoiceTest{
    public static void main(String [] args) {
        Invoice invoiceObject = new Invoice();
        invoiceObject.simpleMessage();
    }
}

// This is the second class. I am using NetBeans so each class is in its own window.

public class Invoice {        
    public void simpleMessage() {
        System.out.println("This is another class");
    }
}

Answer 1

它们是否在同一个.java文件中？ java编译器每个源文件只需要一个java类。

Answer 2

您不需要两个单独的课程。一节课有效。

public class Invoice {        
    public void simpleMessage() {
        System.out.println("This is another class");
    }

    public static void main(String[] args) {
        Invoice invoiceObject = new Invoice();
        invoiceObject.simpleMessage();
    }
}

Answer 3

确实存在奇怪的错误。

如何为类Invoice添加构造函数？

public Invoice（）{ }

将主类连接到其他类

3 个答案: