每日总结七

package dan_ci_lian;

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 DanCiLian {
public static void main(String []srgs){

File file = new File("C:\\Users\\rui'rui\\Desktop\\input20214103.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();
}
}


/*
* 判断只有一个单词
*/
public static boolean oneWord(){
ArrayList<String> list = new ArrayList<String>();
String pathname = "C:\\Users\\rui'rui\\Desktop\\input20214103.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\\rui'rui\\Desktop\\input20214103.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\\rui'rui\\Desktop\\output20214103.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\\rui'rui\\Desktop\\output20214103.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();
}
}

}