标签：todo com stringbu append rac double fileread exception null
IO是JAVASE中非常重要的一块，是面向对象的完美体现，深入学习IO，你将可以领略到很多面向对象的思想。
今天整理了一份适合初学者学习的简单例子，让大家可以更深刻的理解IO流的具体操作。
try { File inputFile = new File(args[0]); if (!inputFile.exists()) { System.out.println("源文件不存在，程序终止"); System.exit(1); } File outputFile = new File(args[1]); InputStream in = new FileInputStream(inputFile); OutputStream out = new FileOutputStream(outputFile); byte date[] = new byte[1024]; int temp = 0; while ((temp = in.read(date)) != -1) { out.write(date); } in.close(); out.close(); } catch (FileNotFoundException e) { // TODO Auto-generated catch block e.printStackTrace(); } catch (IOException e) { // TODO Auto-generated catch block e.printStackTrace(); }String fileName = "D:/date.java.bak"; // String fileName = "D:/test.qqq"; String line; int i = 0, j = 0, f = 0, k = 0; try { BufferedReader in = new BufferedReader(new FileReader(fileName)); line = in.readLine(); while (line != null) { // System.out.println(line); char c[] = line.toCharArray(); for (int i1 = 0; i1 < c.length; i1++) { // 如果是字母 if (Character.isLetter(c[i1])) i++; // 如果是数字 else if (Character.isDigit(c[i1])) j++; // 是空格 else if (Character.isWhitespace(c[i1])) f++; } line = in.readLine(); k++; } in.close(); System.out .println("字母:" + i + ",数字:" + j + ",空格:" + f + ",行数:" + k); } catch (IOException e) { e.printStackTrace(); }try { BufferedReader br = new BufferedReader(new FileReader( "D:\\test.txt")); StringBuilder sb = new StringBuilder(); while (true) { String str = br.readLine(); if (str == null) break; sb.append(str); } Pattern p = Pattern.compile("aa"); Matcher m = p.matcher(sb); int count = 0; while (m.find()) { count++; } System.out.println("\"aa\"一共出现了" + count + "次"); } catch (FileNotFoundException e) { e.printStackTrace(); } catch (IOException e) { e.printStackTrace(); }try { // 方法一 BufferedReader br = new BufferedReader(new FileReader(new File( "D:\\1.xls"))); // StringBuilder bd = new StringBuilder(); StringBuffer bd = new StringBuffer(); while (true) { String str = br.readLine(); if (str == null) { break; } System.out.println(str); bd.append(str); } br.close(); // System.out.println(bd.toString()); // 方法二 InputStream is = new FileInputStream(new File("d:\\1.xls")); byte b[] = new byte[Integer.parseInt(new File("d:\\1.xls").length() + "")]; is.read(b); System.out.write(b); System.out.println(); is.close(); // 方法三 Reader r = new FileReader(new File("d:\\1.xls")); char c[] = new char[(int) new File("d:\\1.xls").length()]; r.read(c); String str = new String(c); System.out.print(str); r.close(); } catch (RuntimeException e) { // TODO Auto-generated catch block e.printStackTrace(); } catch (FileNotFoundException e) { // TODO Auto-generated catch block e.printStackTrace(); } catch (IOException e) { // TODO Auto-generated catch block e.printStackTrace(); }try { PrintWriter pw = new PrintWriter(new FileWriter("d:\\1.txt")); BufferedWriter bw = new BufferedWriter(new FileWriter(new File( "d:\\1.txt"))); OutputStream os = new FileOutputStream(new File("d:\\1.txt")); // 1 os.write("ffff".getBytes()); // 2 // bw.write("ddddddddddddddddddddddddd"); // 3 // pw.print("你好sssssssssssss"); bw.close(); pw.close(); os.close(); } catch (IOException e) { // TODO Auto-generated catch block e.printStackTrace(); }try { BufferedReader br = new BufferedReader(new FileReader(new File( "d:\\2.txt"))); StringBuffer sb = new StringBuffer(); while (true) { String str = br.readLine(); if (str == null) { break; } sb.append(str + "、"); } String str = sb.toString(); String s[] = str.split("、"); double d[] = new double[s.length]; for (int i = 0; i < s.length; i++) { d[i] = Double.parseDouble(s[i]); } for (int i = 0; i < d.length; i++) { System.out.println(d[i]); } br.close(); } catch (FileNotFoundException e) { // TODO Auto-generated catch block e.printStackTrace(); } catch (IOException e) { // TODO Auto-generated catch block e.printStackTrace(); }标签：todo com stringbu append rac double fileread exception null
原文地址：http://www.cnblogs.com/fan-yuan/p/6051337.html
