Question

如何实施以下内容？

我有一个LinkedList列表。 list由命令行初始化，并带有2个参数。我们的LinkedList实现的命令行是

java LinkedList maxSize fileName

fileName是.txt文件。第一个如下：

input1.txt
insert 10
Insert 15
inSert 20
delete 35
insert 35
find 12
find 35
delete 20

我们的产出是：

insert 10 true
Insert 15 true
inSert 20 true
delete 35 false
insert 35 true
find 12   false
find 35   true
delete 20 true

这意味着我们忽略了字符的大小写，只关心插入，删除和查找命令。 fileName有我们的命令（方法）在LinkedList.java中运行并给我们提供密钥。 commandLine将我们的LinkedList初始化为set maxSize并传入输入文件以进行测试。

我的问题是：如何从fileName读取命令并读取密钥以便我可以执行适当的方法调用？我正在考虑使用扫描仪。我们可以假设所有命令都是一行和有效的语法。我们还可以假设maxSize足够大以反映给定的输入/输出文件。

Answer 1

尝试做类似这样的事情：我使用一个非常类似的方法来完成一个项目，我必须使用链接列表和从文件中读取命令。根据需要修改。基本概念是循环，读取每个命令行，直到达到终止命令/条件，然后打印出结果或您需要为特定实例做的任何事情。

另外，这是另一个有用的链接，几乎正是您所需要的：Using a text file to carry commands in Java

    boolean done = false;
    // Loop runs as long as done != true
    while (!done) {
        line = sc.nextLine();   // Store data gathered from file into String
        String [] tokens = line.split(" "); // Split the string using space as delimiter

        // Switch for processing commands received
        switch (tokens[0]) {

        // Print name followed by newline
        case "N": {
                System.out.println("Evan Clay Bechtol");
                break;
            }

        // Create a memory object of size s
        case "C": {
                memory = new Memory(Integer.parseInt(tokens[1])); // Create a new Memory object
                break;
            }

        // End of data file, print newline and exit
        case "E": {
                System.out.println();
                done = true;    // Break the loop, end the program
                break;
            }

        // Add segment of size 'u' and lifetime 'v' and print confirmation record
        case "A": {
                int size = Integer.parseInt(tokens[1]);
                int lifeTime = Integer.parseInt(tokens[2]);
                timeOfDay++;

                memory.removeSegmentsDueToDepart(timeOfDay);

                // Boolean controls whether confirmation is printed.
                while (!memory.place(size, timeOfDay, lifeTime, true)) {
                    timeOfDay++;
                    memory.removeSegmentsDueToDepart(timeOfDay);
                    } // End while
                placements++;

                // Print confirmation message
                //System.out.println("Added segment of size: " + size + "\t" + "lifeTime: " + lifeTime + "\t" + "Time of Departure: " + (lifeTime + timeOfDay));
                break;  
            }

        // Print the current segments in the list
        case "P": {
                System.out.println ();
                memory.printLayout();
                //System.out.println ("End at time: " + timeOfDay);
                break;
            }

        case "R": {
                int size = Integer.parseInt(tokens[1]); // Size
                memory = new Memory(size);
                int minSegSize = Integer.parseInt(tokens[2]);   // Minimum seg. size
                int maxSegSize = Integer.parseInt(tokens[3]);   // Maximum seg. size
                int maxLifeTime = Integer.parseInt(tokens[4]);  // Maximum lifetime of segs.
                int numSegs = Integer.parseInt(tokens[5]);      // Number of segs. to simulate
                timeOfDay = 0;
                placements = 0;
                Random ran = new Random (); // "Random" number generator

                while (placements < numSegs) {
                    timeOfDay++;
                    memory.removeSegmentsDueToDepart(timeOfDay);
                    int newSegSize = minSegSize + ran.nextInt(maxSegSize - minSegSize + 1);
                    int newSegLifetime = 1 + ran.nextInt(maxLifeTime);
                    totalSpaceTime += newSegSize * newSegLifetime;

                    while (!memory.place(newSegSize, timeOfDay, newSegLifetime, false)) {
                        timeOfDay++;
                        memory.removeSegmentsDueToDepart(timeOfDay);
                    } // End while
                    placements++;
                } // End while

                // Print final summary of execution
                meanOccupancy = totalSpaceTime / (timeOfDay);
                System.out.printf ("Number of placements made =  %6d", placements);
                System.out.println();
                System.out.printf ("Mean occupancy of memory  = %8.2f", meanOccupancy);
                System.out.println();
            }
        } // End switch
    } // End while
    sc.close();

从命令行从文件中获取命令

1 个答案: