三月六号

今日学习

import java.io.BufferedReader;
import java.io.BufferedWriter;
import java.io.File;
import java.io.FileReader;
import java.io.FileWriter;
import java.io.IOException;
import java.util.ArrayList;

public class english {
    public static void main(String []srgs){

        File file = new File("C:\\Users\\DELL\\Desktop\\资料\\JAVA TWO\\input.txt");
        System.out.println("判断文件格式是否正确：");
        if(file.exists() && file.length() == 0) {
            System.out.println("  文件为空！");
            System.exit(0);
        } else if(oneWord()){
            System.out.println("  文件只有一個單詞！");
            System.exit(0);
        }else{
            System.out.println("  文件内容有效。");
            achieve();
        }
    }
    public static boolean oneWord(){
        ArrayList<String> list = new ArrayList<String>();
        String pathname = "C:\\Users\\DELL\\Desktop\\资料\\JAVA TWO\\input.txt";
        int i = 0;
        try (
                FileReader reader = new FileReader(pathname);
                BufferedReader br = new BufferedReader(reader)
                // 建立一个对象，它把文件内容转成计算机能读懂的语言
        ) {
            String line;
            //网友推荐更加简洁的写法
            while ((line = br.readLine()) != null) {
                // 一次读入一行数据
                list.add(line);
                i++;
            }
        } catch (IOException e) {
            e.printStackTrace();
        }
        if(i<=1){
            return true;
        }else{
            return false;
        }
    }

    /*
     * 获取单词首尾字母的方法
     */
    public static void print(){
        String a = "sadfg";
        System.out.println(a.substring(0,1));//获取首字母
        System.out.println(a.substring(a.length()-1,a.length()));//获取尾字母
    }


    /*
     * 读取txt文件，并且存到ArrayList集合中,找出接龙单词 存入ArrayList1集合，
     * 把ArrayList1集合写入output1文件
     */
    public static void achieve() {
        ArrayList<String> list = new ArrayList<String>();
        ArrayList<String> list1 = new ArrayList<String>();//存储遍历结果

        String pathname = "C:\\Users\\DELL\\Desktop\\资料\\JAVA TWO\\input.txt"; // 绝对路径或相对路径都可以，写入文件时演示相对路径,读取以上路径的input.txt文件
        String writename = "C:\\Users\\DELL\\Desktop\\资料\\JAVA TWO\\output.txt";
        //防止文件建立或读取失败，用catch捕捉错误并打印，也可以throw;
        //不关闭文件会导致资源的泄露，读写文件都同理
        //Java7的try-with-resources可以优雅关闭文件，异常时自动关闭文件；详细解读https://stackoverflow.com/a/12665271
        try (FileReader reader = new FileReader(pathname);
             BufferedReader br = new BufferedReader(reader); // 建立一个对象，它把文件内容转成计算机能读懂的语言
             FileWriter writer = new FileWriter(writename);
             BufferedWriter out = new BufferedWriter(writer)
        ) {
            String line;
            //网友推荐更加简洁的写法
//            System.out.println("遍历readline");
            while ((line = br.readLine()) != null) {
                // 一次读入一行数据
//                System.out.println(line);
                list.add(line);
            }
            System.out.println("遍历所有单词集合（arraylist）：");
            for (int i = 0; i < list.size(); i++) {
                System.out.println(list.get(i));
            }


            String word0 = list.get(0);
            list1.add(word0);
            String word = " ";//用来存储单词
            for(int j = 1;j < list.size();j++){
                word = list.get(j);
                if(word.substring(0,1).equals(word0.substring(word0.length()-1,word0.length())) )
                //不能用“==”判断字符串的等价，要用equals!!!!!!!!!!!!!!!!!!!!!!!!
                {
                    list1.add(word);
                    word0 = word;
                }
            }
            //打印list1
            System.out.println("遍历list1");
            //把list1中的结果写入output1.txt文件
            for (int g = 0; g < list1.size(); g++){
                System.out.println(list1.get(g));
                out.write(list1.get(g));
                out.write(" ");
            }

            System.out.println("程序结束！");


        } catch (IOException e) {
            e.printStackTrace();
        }
    }

    /*
     * txt文件的读取
     */
    public static void readFile() {
        String pathname = "input.txt";
        //不关闭文件会导致资源的泄露，读写文件都同理
        //Java7的try-with-resources可以优雅关闭文件，异常时自动关闭文件；详细解读https://stackoverflow.com/a/12665271
        try (FileReader reader = new FileReader(pathname);
             BufferedReader br = new BufferedReader(reader) // 建立一个对象，它把文件内容转成计算机能读懂的语言
        ) {
            String line;
            while ((line = br.readLine()) != null) {
                // 一次读入一行数据
                System.out.println(line);
            }
        } catch (IOException e) {
            e.printStackTrace();
        }
    }

    /*
     *txt文件的写入
     */
    public static void writeFile() {
        try {
            File writeName = new File("C:\\Users\\DELL\\Desktop\\资料\\JAVA TWO\\output.txt");
            writeName.createNewFile(); //创建新文件,有同名的文件的话直接覆盖
            try (
                    FileWriter writer = new FileWriter(writeName);
                    BufferedWriter out = new BufferedWriter(writer)
            ) {
                out.write("我会写入文件啦！\r\n"); // \r\n为换行
                out.flush(); // 把缓存区内容压入文件
            }
        } catch (IOException e) {
            e.printStackTrace();
        }
    }


}