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Created by alfa on July 15, 2011 13:25:45    Last update: July 15, 2011 13:25:45
Read the whole contents of a file into a String. It's better to read the whole file as bytes and convert to String than to read the file line by line and concatenate the lines. String getFileContents(String fileName) throws... Using java.nio : import java.io.FileInputStream; import java...
Created by Dr. Xi on July 13, 2011 16:18:05    Last update: July 13, 2011 16:18:05
The goal is to read a file like this: for (String line: textFileReader) { // do s... This is the code: import java.io.*; import java.util.Iterator; ...
Created by Dr. Xi on June 22, 2011 07:33:45    Last update: June 22, 2011 11:57:54
Demo code for CSV parsing with OpenCSV . Java code: import java.io.*; import au.com.bytecode.opencs... Test with a simple CSV file: psmith01,CLASS2B,Peter Smith 1,YEAR2,1,N,ADVANCED,... The parser worked correctly: Line 1 has 11 values: |psmith01| |CLASS2B|... Test with a more complicated CSV file: "psmith01 abc", "CLASS2B " , " Peter... Result: Line 1 has 4 values: |psmith01 abc| |CLASS... The parser: Escaped quote and backslash correctly Ignored spaces before the quotation mark - sometimes (see below) Counted spaces after the right quotation mark till the comma as content, including the right quotation mark (bug). Ignored improperly quoted item - silently (third line) Indeed, the OpenCSV parser has a problem with spaces: Input: "Smith, Jack", "210-345-8888" "Smith, J... Result: Line 1 has 2 values: | Smith, Jack| |210-3......
Created by Dr. Xi on June 22, 2011 09:42:35    Last update: June 22, 2011 11:39:40
Demo code for CSV parsing with Skife CSV . Java code: import java.io.*; import java.util.*; import... Test with a simple CSV file: psmith01,CLASS2B,Peter Smith 1,YEAR2,1,N,ADVANCED,... The parser worked correctly: Line 1 has 11 values: |psmith01| |CLASS2B|... Test with a more complicated CSV file: "psmith01 abc", "CLASS2B " , " Peter... Result: Line 1 has 4 values: |psmith01 abc| | CLAS... The parser worked correctly. But notice that it counts the spaces outside of the quotes significant, and doing so consistently. One more test for spaces: "Smith, Jack" , "210-345-8888" "Smith, Jack"... Result: Line 1 has 2 values: | Smith, Jack | | 210... Add a new line in item two: "One", "Two ", "Three" Result: Line 1 has 2 values: |One| | Two| L...
Created by Dr. Xi on June 21, 2011 15:41:51    Last update: June 22, 2011 11:33:36
Demo code for CSV parsing with Apache Commons CSV parser . Java code: import java.io.*; import org.apache.commons.csv... Test with a simple CSV file: psmith01,CLASS2B,Peter Smith 1,YEAR2,1,N,ADVANCED,... Result: Line 1 has 11 values: |psmith01| |CLASS2B|... The parser worked correctly. Test with a more complicated CSV file: "psmith01 abc", "CLASS2B " , " Peter... Result: Line 1 has 4 values: |psmith01 abc| |CLASS... The third line is invalid input, but throwing a Java IOException is a bit grave. Also, the parser is not able to escape a backslash. Add a new line in item two: "One", "Two ", "Three" Result: Line 2 has 3 values: |One| |Two | |...
Created by Dr. Xi on June 21, 2011 15:54:00    Last update: June 22, 2011 11:33:09
Demo code for CSV parsing with SuperCSV parser . Java code: import java.io.*; import java.util.List; imp... Test with a simple CSV file: psmith01,CLASS2B,Peter Smith 1,YEAR2,1,N,ADVANCED,... The parser worked correctly: Line 1 has 11 values: |psmith01| |CLASS2B|... Test with a more complicated CSV file: "psmith01 abc", "CLASS2B " , " Peter... The parser messed up on all three lines: Line 1 has 5 values: |psmith01 abc| |CLASS... Using two lines input: "psmith01 abc", "CLASS2B " , " Peter... It generates an exception: Line 1 has 5 values: |psmith01 abc| |CLASS... Add a new line in item two: "One", "Two ", "Three" Result: Line 2 has 3 values: |One| |Two | |...
Created by Dr. Xi on June 22, 2011 07:12:02    Last update: June 22, 2011 11:32:02
Demo code for CSV parsing with OstermillerUtils . Java code: import java.io.*; import java.util.List; imp... Test with a simple CSV file: psmith01,CLASS2B,Peter Smith 1,YEAR2,1,N,ADVANCED,... The parser worked correctly: Line 1 has 11 values: |psmith01| |CLASS2B|... Test with a more complicated CSV file: "psmith01 abc", "CLASS2B " , " Peter... The parser messed up on all three lines: Line 1 has 6 values: |psmith01 abc| | "CLA... Putting a space before the first quote: "Smith, Jack","210-345-8888" It dismissed the quotes: Line 1 has 3 values: | "Smith| | Jack"| ... Add a new line in item two: "One", "Two ", "Three" Result: Line 1 has 2 values: |One| | "Two| ...
Created by alfa on June 02, 2011 13:04:18    Last update: June 02, 2011 13:04:18
Some javap usage examples. Start from HelloWorld.java : @Deprecated public class HelloWorld { pu... javap -c HelloWorld outputs: Compiled from "HelloWorld.java" public class He... javap -v HelloWorld outputs ( -v for verbose mode): Compiled from "HelloWorld.java" public class He... The output consists of: " Compiled from... " header Class attributes. For the HelloWorld example, there are two: SourceFile and Deprecated . Minor and major class file version Constant pool Disassembled code LineNumberTable for debugging purposes. javap by default only prints package/protected/public members. To display all members including private, use the -p switch. javap -v -p HelloWorld
Created by alfa on May 25, 2011 20:17:52    Last update: May 25, 2011 20:39:35
In Java regex, by default, the dot character does not match the newline character ( \n ). It matches a newline character only when the DOTALL flag is set. Example: import java.util.regex.*; public class Dota...
Created by alfa on May 25, 2011 20:08:21    Last update: May 25, 2011 20:08:21
In MULTILINE mode, ^ matches the begging of the string as well as the beginning of a new line; $ matches the end-of-string as well as the newline character. In normal (non- MULTILINE mode), ^ only matches the begging of the string; $ only matches the end-of-string. Example: import java.util.regex.*; public class ...
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