did not live in the company dry , review a bit IO, found that many have forgotten, so badly written, just enough for beginners to use . I put my review process to write code stickers, we learn together , and please enlighten enlighten ha. Incidentally discuss IO
1, file copy
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();
}
2, java read documents: a directory to achieve statistical letters that appear in each file number , number of digits , spaces, and the number of rows, there is no alternative other characters
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();
}
3, from the file (d: \ test.txt) was found in the string "aa" number of occurrences
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();
}
4, three ways to read the file
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();
}
5, three ways to write file
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();
}
6, reads the file , and to read each line into an array of type double
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();
}
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give a little advice , in fact, still very simple IO streams , as long as we imagine the stream and the target file into pipes and buckets easily understood and programmed !
not know whether you have seen those top masters say IO This chapter of the video , giving the image a very deep !
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I was a beginner , I feel quite right for me .
LZ, xiexie .....
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import java.io. *;
public class CopyBytes {
public static void main (String [] args) throw IOException {
File inputFile = new File ("farrago.txt");
File outputFile = new File ("outagainb.txt");
FileInputStream in = new FileInputStream (inutFile)
FileOututStream out = new FileOutputStream (outputFile);
int c;
while ((c = in.read ())! = -1)
out.write (c);
in.close ();
out.close ();
}
}
This is my copy of the book explains the landlord files copied code established under the byte date [] = new byte [1024]
and date do in.read () parameters do
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good support it.
But IO best in finally close oh
------ Solution ----------------- ---------------------------
try {
File inputFile = new File (args [0]);
if (! inputFile.exists ()) {
System.out.println (" Source file does not exist , the program termination " ) ;
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 ();
}
------ Solution ------------------------------------ --------
EXCEL code read as follows:
import java.io. *;
import jxl. *;
public class exercise
{
public static void main (String args [])
{
try
{
Workbook book = Workbook.getWorkbook (new File ("D : \ \ 1.xls "));
Sheet sheet = book.getSheet (0);
Cell cell1 = sheet.getCell (0, 0);
String result = cell1.getContents ();
System.out.println (result);
book.close ();
}
catch (Exception e)
{
System.out.println (e);
}
}
}
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for example, there are many relatively junior delete these files are created , I do not stick out, we believe that these are no problem. I posted mainly for file read and write operations
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I was a beginner , I feel quite right for me .
LZ, xiexie .....
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I am also new to the ah thank you ah
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looked a long time , I did not understand
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will be a !
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landlord , recently I'm confused here. . . Have to say . . . You came just in time
Dingdingding
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" the perfect embodiment of the object-oriented "
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I was a beginner , I feel quite right for me .
LZ, xiexie .....
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not review what really forget !
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is indeed the case . It is important programming ideas, I found it a really IO is the perfect embodiment of the object-oriented , abstract classes and interfaces , polymorphism, various design patterns reflected on the inside of the head. Careful studies is good.
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my column was incomplete, a lot of things I do not Tieshanglai . For example, to write the file , there are several ways .
Today, only the realization of functional literacy , and the difference between the specific variety of handy, you do it slowly . Some things can only sense it , -
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Oh programming is cattle
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make the whole more useless
IO stream to figure out two , byte and character streams
then understand decorative pattern on the end. . .
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Thank you to share
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useful summary of benefit , thanks prawns .
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also
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Thank you to share
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landlord did not make it clear, just out of the program . . . .
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Thank landlord .
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LZ able to read large files you write such a TXT file parsing 60M above . facie landlord method ?
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Thank you to share , and see nothing wrong !
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my whole are the primary use. Just look at the API just write something, it is certainly not specific . Otherwise you are tidy , let me learn everyone
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useful ah , thank you
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Recommended landlord spirit !
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newcomers, thank landlord recommended !
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this post must be collections
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good ah ! Thank you !
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posts per day back to get 10 points that can be available points ! yeah
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feel quite right for me .
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first reply then look
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thank you for sharing , very useful
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thank you for sharing , very useful
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c = in.read (), you this is one byte a word section to read, then a byte by byte write .
byte date [] = new byte [1024], this is the first 1024 bytes of space to open up , and then one reads the byte into the date in 1024 , and then once the data is written to date inside.
You say, what efficiency ?
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you're quite right, in development are generally in the finally close the .
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collection , the future will be used ! LZ thanks !
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bother !
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landlord mighty dragon powerful
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Thank LZ a ~
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IO simply looking through the book , a routine !
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Excel file you can actually read the draw , you're too strong ! ! ! !
I would like to know if you read something out of the horse is God ! ! ! !
estimated that only God can recognize a horse piles astronomical character . . . . .
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good, thank you ! !
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I love this ecstasy ~
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escel there is something, read out is something. Proposed multi -on practice exercises
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excel, engage engage it
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just need to thank you sharing
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Thank you to share !
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xls landlord should also be used to read some of the external package it
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collection / / content is too short ?
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Thank you, thank
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an empty excel sheet read something as follows :
Mi as??? {00020P819-
Document = ThisWorkbook / & H00000000
Document = Sheet1 / & H00000000
Document = Sheet2 / & H00000000
Document = Sheet3 / & H00000000
Name = "VBAProject"
HelpContextID = "0"
VersionCompatible32 = "393222000"
CMG = "1416F73A79F97DF97DF97DF97D"
DPB = "D7D5347B34FDF6FEF6FEF6"
GC = "9A9879B83DB93DB9C2"
[Host Extender Info]
& H00000001 = {3832D640-CF90-11CF-8E43-00A0C911005A}; VBE; & H00000000
[Workspace]
ThisWorkbook = 0, 0, 0, 0, C
Sheet1 = 0, 0, 0, 0, C
Sheet2 = 0, 0, 0, 0, C
Sheet3 = 0, 0, 0, 0, C
there are many bible characters do
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landlord · how are · processing node stream flow is it ? Data stream it ? Object stream it ?
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I posted the only part , looked at yesterday posted today , is a bit chaotic.
Today I tidied , feel more self- improvement .
feel downright had time to study , it now appears is actually very simple . Mainly input and output streams , character byte stream , then the stream of bytes into characters converted , buffered input and output streams , and so on.
clarify the class hierarchy , decorative design pattern clear, all came out. Still very regular.
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experts to supplement it
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you tell me something about how to use input and output streams do ? They can print something , I do not know when to use ah , I was inexperienced ,
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landlord really to force ,
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while ((temp = in.read (date)) ! = -1 ) {
out.write (date);
}
in.close ();
out.close ();
read and write streams in here to close the case, is likely to cause internal occupy finished, the server crashes
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taught , and very practical.
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write so-so
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zan lz
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hope that the landlord can hang a little more advanced stuff ! Let's sightseeing !
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IO important is what the flow on the line selected
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] +1
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thanks for sharing !
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Thank landlord ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~
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