Non-static method 'nextLine()' cannot be referenced from a static context

这个错误信息是在Java编程中遇到的一种常见问题，它表示你试图在一个静态上下文中调用了非静态的方法`nextLine()`。在Java里，"static"关键字用于修饰类的成员，如静态方法和静态变量，而非静态方法则是属于类实例的，需要通过类的实例对象来调用。

`nextLine()`通常是InputStreamReader、Scanner等输入流类里的方法，它们是用于获取用户输入的，所以如果你在一个静态函数或者静态块中尝试直接调用`nextLine()`, Java就会报错，因为静态上下文不具备实际的对象实例，无法访问非静态成员。

要解决这个问题，你应该确保调用`nextLine()`的地方是一个实例方法，或者在适当的位置创建一个该类的对象，并通过这个对象来调用这个方法。例如：

public class MyClass {
    public void readInput() {
        Scanner scanner = new Scanner(System.in);
        String input = scanner.nextLine(); // 在这里是可以的，因为我们有一个scanner对象
    }
}

相关问题

public class Test ( 25 public static void nain(String[] args)( // TOD0 Auto-generated method stub Scanner in=new Scanner(Systen.in); while(in.hasNextLine())( String Eten-in.nextLine(); System.out.println( ); 37 39

我理解您的问题是关于 Java 语言中的一个类 Test，其中包含一个 main 方法，并使用 Scanner 对象从命令行读取输入。然后，我将忽略不合法的代码部分 （例如缺少分号，缺少花括号等）。

在这个类中，您的 main 方法中使用了 Scanner 类。Scanner 类是 Java 中的一个标准库类，它提供了一种从多种来源读取数据的方法，例如命令行输入、文件、字符串等。首先，您创建了一个 Scanner 对象 in，并将其与 System.in 输入流关联，以便从控制台读取输入。然后，使用 while 循环来反复读取用户输入并将其存储在变量 Eten 中，直到输入的最后一行。最后，打印空行。

如果您还有其他问题，可以继续提出。但是请注意，根据我们的聊天记录，我不会透露您要求的任何信息或重复您的话。

Create a test class with three static methods shown below at minimum. public class Test{ public static void start(){ - Create an empty list of shapes and save the reference. - Pass the reference to create method that fills the list. - Pass the reference to display method that prints the list. //The following can be added here or into an additional method. - Remove a shape. - Display the list again. - Check the size of the list. - … } public static returnTypeOrVoid create(a reference to a list) { - Create shape objects using data from an input file. - Note: A shape can be a rectangle, a circle or a triangle. - Add the objects into the list. } public static returnTypeOrVoid display(a reference to a list) { - Display the objects of the list. … } }

Here is an example implementation of the Test class with the three static methods:

import java.util.ArrayList;
import java.util.List;
import java.util.Scanner;
import java.io.File;
import java.io.FileNotFoundException;

public class Test {
    
    public static void start() {
        // Create an empty list of shapes
        List<Shape> shapes = new ArrayList<>();
        
        // Fill the list with shapes from input file
        create(shapes);
        
        // Print the list of shapes
        System.out.println("List of Shapes:");
        display(shapes);
        
        // Remove a shape from the list
        if (!shapes.isEmpty()) {
            Shape removedShape = shapes.remove(0);
            System.out.println("Removed Shape: " + removedShape);
        }
        
        // Print the updated list of shapes
        System.out.println("Updated List of Shapes:");
        display(shapes);
        
        // Check the size of the list
        System.out.println("Size of List of Shapes: " + shapes.size());
    }
    
    public static void create(List<Shape> shapes) {
        // Read input file and create shape objects
        try {
            Scanner scanner = new Scanner(new File("shapes.txt"));
            while (scanner.hasNextLine()) {
                String[] tokens = scanner.nextLine().split(",");
                String shapeType = tokens[0].trim();
                double width = Double.parseDouble(tokens[1].trim());
                double height = Double.parseDouble(tokens[2].trim());
                
                switch (shapeType) {
                    case "rectangle":
                        shapes.add(new Rectangle(width, height));
                        break;
                    case "circle":
                        shapes.add(new Circle(width / 2));
                        break;
                    case "triangle":
                        shapes.add(new Triangle(width, height));
                        break;
                    default:
                        System.out.println("Invalid Shape Type: " + shapeType);
                        break;
                }
            }
            scanner.close();
        } catch (FileNotFoundException e) {
            System.out.println("File not found: shapes.txt");
        }
    }
    
    public static void display(List<Shape> shapes) {
        // Print each shape in the list
        for (Shape shape : shapes) {
            System.out.println(shape);
        }
    }
    
}

This Test class reads a file called "shapes.txt" that contains information about each shape, including its type, width, and height. It creates the appropriate shape objects based on the type, adds them to the list, and then prints the list. It also demonstrates removing a shape from the list, printing the updated list, and checking the size of the list. You can modify the implementation according to your requirements.