从命令行获取文件中的命令

Question

如何实施以下内容？

我有一个 LinkedList 列表。列表由命令行初始化并接受 2 个参数。我们的 LinkedList 实现的命令行是

java LinkedList maxSize fileName

fileName 是一个 .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

我们的输出是：

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

这意味着我们忽略字符的大小写，只关心命令插入、删除和查找。 fileName 在 LinkedList.java 中有我们对运行的命令（方法），并为我们提供了密钥。 commandLine 将我们的 LinkedList 初始化为一组 maxSize 并传入输入文件以进行测试。

我的问题是：如何从 fileName 中读取命令并读取密钥以便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且语法有效。我们还可以假设 maxSize 足够大以反映给定的 input/output 个文件。

Answer 1

尝试做这样的事情：我对一个项目使用了非常相似的方法，我必须使用 linked-lists 并从文件中读取命令。根据需要修改。基本概念是你循环，读取每个命令行直到你到达终止 command/condition，然后打印出结果或你需要为你的特定实例做的任何事情。

此外，还有一个有用的 link，它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();

从命令行获取文件中的命令

Take commands from a file from command line

java

file

command-line

linked-list

java.util.scanner