java课程课后作业190606之计算最长英语单词链

一个文本文件中有N 个不同的英语单词，我们能否写一个程序，快速找出最长的能首尾相连的英语单词链，每个单词最多只能用一次。最长的定义是：最多单词数量，和单词中字母的数量无关。

统一输入文件名称：input1.txt， input2.txt

统一输出文件名称：output1.txt，output2.txt

程序需要考虑下列异常状况：

例如，文件不存在，你的程序会崩溃么，还是能优雅地退出并给用户提示信息？

如果文件没有任何单词、只有一个单词、没有可以首尾相连的单词，程序应该如何输出？

这里虽然我实现了这个功能，但是算法的复杂度过高，并不是理想的算法，所以就不在阐述，只给出下面的异常情况处理

public class test {

    private static String WORDSUM = "";

    private static int num=0;

    static String[] TempSUM=null;

    public static void main(String[] args) throws Exception {

        // TODO Auto-generated method stub

        String[] temp={"apple","ant","ban","element","televetion","tv","ppt","nation"};

        File file = new File("C:/D/inmmmput.txt");

        boolean FileExists= judeFileExists(file);

        if(FileExists==false)

        {

            System.out.println("文件不存在............");

        }else {

            System.out.println("文件存在............");

            if(judeFileSize(file)==false)

            {

                System.out.println("文件没有内容...........");

            }

            else {

                ReadBook();

                String Maxnumber=run(TempSUM);

                WriteStringToFile(Maxnumber);

            }

        }

    }

    private static String run(String temp[]) {

        String MaxNumber=null;

        int Max=0;

        int get=0;

        if(temp.length>1)

        {

            for(int j=0;j<temp.length;j++)

            {

                System.out.println("开始的字母"+temp[j]);

                if(!temp[j].isEmpty())

                {

                    String number=temp[j];

                    String numberLast=temp[j].substring(temp[j].length()-1, temp[j].length());

                    for(int i=j+1;i<temp.length;i++)

                    {

                        if(!temp[i].isEmpty())

                        {

                            System.out.println("读取的单词"+temp[i]);

                            System.out.println("读取的单词开头字母"+temp[i].substring(0, 1));

                            System.out.println("上一个的单词结尾字母"+numberLast);

                            if(temp[i].substring(0, 1).equals(numberLast))

                            {

                                number=number+"--"+temp[i];

                                System.out.println("匹配成功连接"+number);

                            }

                            numberLast=number.substring(number.length()-1, number.length());

                            get++;

                        }

                        System.out.println(number);

                        if(Max<=get)

                        {

                            MaxNumber=number;

                            Max=get;

                            System.out.println("目前值"+get);

                    }

                        get=0;

}

                }

                System.out.println("最大值"+Max);

            }

            if(Max==1)

            {

                System.out.println("没有首尾相连啊");

            }

            return MaxNumber;

        }

        else {

            System.out.println("只有一个哦。。");

            return "null";

        }

    }

    // 判断文件是否存在

    public static boolean judeFileExists(File file) throws IOException {

          if (file.exists()) {

            return true;

            } else {

                return false;

            }

    }

    //判断文件的大小

    private static boolean judeFileSize(File file) {

        if(file.length()<=0)

        {

            return false;

        }

        else {

            return true;

        }

    }

    public static void WriteStringToFile(String number) throws IOException {

        try {

            String filePath="C:/D/output.txt";

            File file = new File(filePath);

            if(judeFileExists(file))

            {

                PrintStream ps = new PrintStream(new FileOutputStream(file));

                ps.println(number);// 往文件里写入字符串

                ps.close();

                System.out.println("已经写入文件");

            }

            else {

                System.out.println("输出文件不存在");

            }

        } catch (FileNotFoundException e) {

            // TODO Auto-generated catch block

            e.printStackTrace();

        }

    }

    public static void ReadBook()throws Exception

    {

        String book=book("C:/D/input.txt");

        System.out.println(book);

    }

    private static String book(String file) throws IOException

    {

        // TODO Auto-generated method stub

        File f=new File(file);

        BufferedReader bf=new BufferedReader(new FileReader(f));

        String content="";

        int lenth=0;

        int x=0;

        StringBuilder sb=new StringBuilder();

        String[] sum= {""};

        while(content!=null)

        {

            WORDSUM=WORDSUM+content;

            content= bf.readLine();

            if(content==null)

                break;

        }

        WORDSUM=WORDSUM.replace(".",",");

        WORDSUM=WORDSUM.replace(";",",");

        WORDSUM=WORDSUM.replace("!",",");

        WORDSUM=WORDSUM.replace("?",",");

        WORDSUM=WORDSUM.replace("-",",");

        WORDSUM=WORDSUM.replace("“",",");

        WORDSUM=WORDSUM.replace("”",",");

        WORDSUM=WORDSUM.replace("‘",",");

        WORDSUM=WORDSUM.replace("’",",");

        WORDSUM=WORDSUM.replace("(",",");

        WORDSUM=WORDSUM.replace(")",",");

        WORDSUM=WORDSUM.replace(":",",");

        WORDSUM=WORDSUM.replace("—",",");

        WORDSUM=WORDSUM.replace("　",",");

        WORDSUM=WORDSUM.replace(" ",",");

        TempSUM = WORDSUM.split(",");

        return sb.toString();

    }

}

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java课程课后作业190606之计算最长英语单词链

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