java核心基础练习

package com.wh.text;

import java.io.BufferedReader;

import java.io.BufferedWriter;

import java.io.File;

import java.io.FileInputStream;

import java.io.FileNotFoundException;

import java.io.FileOutputStream;

import java.io.IOException;

import java.io.InputStreamReader;

import java.io.OutputStreamWriter;

import java.io.UnsupportedEncodingException;

public class textutil {

/

*

* 如何使用java去除掉字符串前面的空格

* */

public static String replaceTextFirstBlack(String s){

for(int i=0;i<s.length();i++){

if(s.charAt(i)!=' '){

s=s.substring(i,s.length());

break;

}

}

return s;

}

/*

*

去除掉每一行中前面几个数字：

原来：

196 112<url>http://34567maven.aliyun.com/nexus/content/repositories/central/</url>

结果 ：

112<url>http://34567maven.aliyun.com/nexus/content/repositories/central/</url>

* */

public static String removeTextFirstNum(String string){

//System.out.println(replaceTextFirstBlack(string));

String str=string.trim();

String newStr = str.replaceAll("^([0-9]+)(\s?)", "");

//^([0-9]+)(\s?)$

//System.out.println(string.trim());

System.out.println(newStr);

return newStr;

}

public static File removeFileTextFirstNum(File InputFile,File OutputFile) throws UnsupportedEncodingException, FileNotFoundException{

//File f=new File("d:/res.txt");

try {

FileInputStream fis=new FileInputStream(InputFile);

InputStreamReader isr=new InputStreamReader(fis, "UTF-8");

BufferedReader br = new BufferedReader(isr);

java核心基础练习

//写入中文字符时解决中文乱码问题

FileOutputStream fos=new FileOutputStream(OutputFile);

OutputStreamWriter osw=new OutputStreamWriter(fos, "UTF-8");

BufferedWriter bw=new BufferedWriter(osw);

//简写如下

//BufferedReader br = new BufferedReader(new InputStreamReader(

// new FileInputStream("E:/1556.txt"), "UTF-8"));

String line="";

// String[] arrs=null;

while ((line=br.readLine())!=null) {

// arrs=line.split(",");

// System.out.println(arrs[0] + " : " + arrs[1] + " : " + arrs[2]);

line=removeTextFirstNum(line);

bw.write(line+"

");

}

//简写如下：

//BufferedWriter writer = new BufferedWriter(new OutputStreamWriter(

// new FileOutputStream(new File("E:/1556.txt")), "UTF-8"));

// for(String arr:arrs){

// bw.write(arr+"

");

// }

br.close();

isr.close();

fis.close();

//注意关闭的先后顺序，先打开的后关闭，后打开的先关闭

bw.close();

osw.close();

fos.close();

} catch (IOException e) {

// TODO Auto-generated catch block

e.printStackTrace();

}finally {

}

return OutputFile;

}

public static void main(String[] args) {

TextReplaceTextFirstBlack();

}

private static void TextReplaceTextFirstBlack() {

String string=" 196 112<url>http://34567maven.aliyun.com/nexus/content/repositories/central/</url>";

System.out.println(replaceTextFirstBlack(string));

String str=string.trim();

String newStr = str.replaceAll("^([0-9]+)(\s?)", "");

//^([0-9]+)(\s?)$

System.out.println(string.trim());

System.out.println(newStr);

try {

removeFileTextFirstNum(new File("C:/Users/Administrator/Desktop/copy"),new File("d:/res.txt"));

} catch (UnsupportedEncodingException e) {

// TODO Auto-generated catch block

e.printStackTrace();

} catch (FileNotFoundException e) {

// TODO Auto-generated catch block

e.printStackTrace();

}

}

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