Test.java

import java.io.BufferedReader;
import java.io.BufferedWriter;
import java.io.File;
import java.io.FileInputStream;
import java.io.FileNotFoundException;
import java.io.FileWriter;
import java.io.IOException;
import java.io.InputStreamReader;

public class Test {
	
	public static void main(String[] args)  {
		test1();
	}
	public static void test1(){
		String param="1225sddfh";
		System.out.println(param.substring(0,1));
		int s=param.length();
		System.out.println(s);
	}
	
	
	public static void reader() throws IOException{
		File fileName=new File("D:\\test.txt");
		try {
			fileName.createNewFile();
			BufferedWriter bWriter=new BufferedWriter(new FileWriter(fileName));
			bWriter.write("哈哈哈哈");
			bWriter.flush();
			bWriter.close();
		} catch (IOException e) {
			// TODO Auto-generated catch block
			e.printStackTrace();
		}
		
		
		 InputStreamReader reader = new InputStreamReader(  
                 new FileInputStream(fileName)); // 建立一个输入流对象reader  
         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 = "";  
         line = br.readLine();   
         while (line != null) {  
             line = br.readLine(); // 一次读入一行数据  
         }  
         System.out.println(line);
	}

}