Computer FAQs & Tips » Programming

Java: How to convert String to array?

Manet — Wed, 11 Feb 2009 04:39:13 +0000

Sometime you get a string in a fixed format and you want individualise it and store them into array so you can manipulate it easier with your other functions.

For example,

String array = "one,two,three,four,five,six,seven,eight,nine";

will become

String[] words = {one,two,three,four,five,six,seven,eight,nine};

Below code is demonstrating how fixed format string can be broken down and stored into array.

Class: StringToArray.java

/**
 * Computer-FAQS.com
 * @author Manet Yim (manet.yim at gmail dot com)
 * @license: GPL v3.0
 */
public class StringToArray {
 
    /**
     * Testing method
     * @param args
     */
    public static void main(String[] args) {
        // your raw string in a fixed format
        String array = "one,two,three,four,five,six,seven,eight,nine";
 
        // converting raw string input array object and display it
        String[] convertedArray = StringToArray.convert(array, ",");
        for (int i = 0; i<convertedArray.length; i++){
            System.out.println(convertedArray[i]);
        }
    }
 
    /**
     * Convert a String s to an Array, where each element in string 
     * seperated by sep
     * 
     * @param str String to be converted
     * @param sep Element seperator
     * @return Array of strings
     */
    public static String[] convert(String str, String sep) {
        StringBuffer sBuf = new StringBuffer(str);
 
        // there is at least one element in the array
        int aSize = 1;
 
        // Counting how many separator in the string
        // result will be the size of new array
        for (int i = 0; i < sBuf.length(); i++) {
            if (sep.indexOf(sBuf.charAt(i)) != -1)
                aSize++;
        }
 
        // create new array object with predefined size
        String[] elements = new String[aSize];
 
        int x, y = 0;
        if (sBuf.indexOf(sep) != -1) {
            while (sBuf.length() > 0) {
                if (sBuf.indexOf(sep) != -1) {
                    x = sBuf.indexOf(sep);
                    if (x != sBuf.lastIndexOf(sep)) {
                        elements[y] = sBuf.substring(0, x);
                        y++;
                        sBuf.delete(0, x + 1);
                    } else if (sBuf.lastIndexOf(sep) == x) {
                        elements[y] = sBuf.substring(0, sBuf.indexOf(sep));
                        y++;
                        sBuf.delete(0, sBuf.indexOf(sep) + 1);
                        elements[y] = sBuf.toString();
                        y++;
                        sBuf.delete(0, sBuf.length());
                    }
                }
            }
        } else {
            elements[0] = sBuf.toString();
        }
        sBuf = null;
        return elements;
    }
 
}

How to copy text file in Java?

Manet — Fri, 30 Jan 2009 01:09:19 +0000

Code below demonstrating how to copy data from one text file to another in Java.

This testing method, is calling FileCopier.copyFile(File, File) to copy content of file test1.css to file test2.css

    public static void main(String[] args) {
        FileCopier.copyFile(new File("D:/TEMP/test1.css"), 
                            new File("D:/TEMP/test2.css"));
    }

Class: FileCopier.java

import java.io.File;
import java.io.FileNotFoundException;
import java.io.FileReader;
import java.io.FileWriter;
import java.io.IOException;
 
public class FileCopier {
 
    /**
     * Testing Method
     * @param args
     */
    public static void main(String[] args) {
        FileCopier.copyFile(new File("D:/TEMP/test1.css"), 
                            new File("D:/TEMP/test2.css"));
    }
 
    /**
     * Copy content of file f1 into file f2
     * @param f1
     * @param f2
     */
    public static void copyFile(File f1, File f2) {
        try {
            FileReader in = new FileReader(f1);
            FileWriter out = new FileWriter(f2);
            int line;
            while ((line = in.read()) != -1) {
                // Read line fromtext file and write to destination file
                out.write(line);
            }
            in.close();
            out.close();
 
        } catch (FileNotFoundException ffx) {
            ffx.printStackTrace();
        } catch (IOException iox) {
            iox.printStackTrace();
        }
    }
 
}

Understand Java break and continue Statements

Manet — Mon, 19 Jan 2009 00:14:57 +0000

Let’s get it right and understand on usage of break and continue Statements in Java Programming Language.

`break` Statement

This statement causes iteration to stop/exit immediately, any line remained after this statement will be ignored by the JVM.

It is used in the following loop

for
while
do…while
switch

`continue` Statement

This statement skips the current iteration of the loop, any line after this statement will not be executed by the JVM until the condition is met.

It is used in the following loop

for
while
do…while

Example code below demonstrating how break and continue statement work

public class BreakContinueStm {
 
    public static void main(String[] args) {
 
        int aBreak = 0;
        int bContinue = 0;
 
        for (int i=1; i<=10; i++){
            if (i == 6){
                // that's enough, exit this for loop here
                break;
            }
            aBreak = i;
            System.out.println("aBreak: " + aBreak);
        }
 
        for (int i=1; i<=10; i++){
            if (i <= 5){
                // not satisfied yet, keep going
                continue;
            }
            bContinue = i;
            System.out.println("bContinue: " + bContinue);
        }
 
    }
 
}

Result of this program, aBreak stops when i = 6 and bContinue starts when i = 6 until end of the loop

aBreak: 1
aBreak: 2
aBreak: 3
aBreak: 4
aBreak: 5
bContinue: 6
bContinue: 7
bContinue: 8
bContinue: 9
bContinue: 10

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How to add or display favicon on a webpage?

Manet — Sat, 17 Jan 2009 00:09:49 +0000

What is favicon?

Favicon is shortcut of favorites icon, also known as website icon, shortcut icon, url icon, or bookmark icon.

On the graphical web browser, this icon locates on the Address bar and Tabs bar as seen in the screenshot below.

Screenshot of favicon

Add favicon

You required to have an image of 16×16 pixels, either PNG, ICO or GIF format

To display favicon to your webpage, add one of the following html code inside depends on which image format you have.

Generate Random Password in Java

Manet — Fri, 16 Jan 2009 11:49:33 +0000

This article demonstrates how to generate random password or string using java.util.Random.

You can define your own set of characters in this string variable

private static final String charset = "!0123456789abcdefghijklmnopqrstuvwxyz";

Class: RandomPassword.java

import java.util.Random;
 
public class RandomPassword {
 
    private static final String charset = "!0123456789abcdefghijklmnopqrstuvwxyz";
 
    public static String getRandomString(int length) {
        Random rand = new Random(System.currentTimeMillis());
        StringBuffer sb = new StringBuffer();
        for (int i = 0; i < length; i++) {
            int pos = rand.nextInt(charset.length());
            sb.append(charset.charAt(pos));
        }
        return sb.toString();
    }
 
    public static void main(String[] args) {
        for (int i = 0; i < 10; i++) {
 
            System.out.println(RandomString.getRandomString(10));
 
            try {
                // if you generate more than 1 time, you must
                // put the process to sleep for awhile
                // otherwise it will return the same random string
                Thread.sleep(100);
            } catch (InterruptedException e) {
                e.printStackTrace();
            }
        }
    }
 
}

Below is the output of this program. It genereates 10 passwords with 10 random character in each password

2b!2!9dc42
1b46d!b690
a536c16b69
8adb1577db
7a4!!ac14a
c!!da703b4
85550483!a
8a!4!53bc4
94282b229b
5a1080a2b1

Use Calendar instead of Date in Java

Manet — Wed, 14 Jan 2009 00:03:14 +0000

Common Issue

When you use java.util.Date object with JDK version higher than 1.1

Date d = new Date();
d.getMonth();

You will get deprecated warning messages when you try to compile

The method getMonth() from the type Date is deprecated

However you can supress the warning message by adding @SuppressWarnings("deprecation") to you main() method

@SuppressWarnings("deprecation")
public static void main(String[] args) {
    ...
}

or adding @SuppressWarnings("unchecked") to other method

@SuppressWarnings("unchecked")
public void otherMethod() {
    ...
}

Note that this can only be used in JDK 5.0+

Alternative

Now let’s forget about working around the deprecated method, let’s learn how to use java.util.Calendar instead

Example code below is showing you how to use Calendar object and format the date in the way you required.

Class: TestCalendar.java

import java.text.SimpleDateFormat;
import java.util.Calendar;
 
public class TestCalendar {
 
    public static void main(String[] args) {
        Calendar current = Calendar.getInstance();
        Calendar last6month = Calendar.getInstance();
        last6month.set(Calendar.MONTH, current.get(Calendar.MONTH) - 6);
 
        SimpleDateFormat dformatter = new SimpleDateFormat(
                "dd/MM/yyyy HH:MM:SS a");
 
        System.out.println("Calendar Object: " + current);
        System.out.println("Default Date: " + current.getTime());
        System.out.println("User Formatted Date: "
                + dformatter.format(current.getTime()));
    }
 
}

Output of this program

Calendar Object: java.util.GregorianCalendar[time=1231889016972,
  areFieldsSet=true,areAllFieldsSet=true,lenient=true,
  zone=sun.util.calendar.ZoneInfo[id="Australia/Sydney",offset=36000000,
  dstSavings=3600000,useDaylight=true,transitions=142,
  lastRule=java.util.SimpleTimeZone[id=Australia/Sydney,offset=36000000,
  dstSavings=3600000,useDaylight=true,startYear=0,startMode=2,startMonth=9,
  startDay=-1,startDayOfWeek=1,startTime=7200000,startTimeMode=1,endMode=2,
  endMonth=2,endDay=-1,endDayOfWeek=1,endTime=7200000,endTimeMode=1]],
  firstDayOfWeek=1,minimalDaysInFirstWeek=1,ERA=1,YEAR=2009,MONTH=0,
  WEEK_OF_YEAR=3,WEEK_OF_MONTH=3 DAY_OF_MONTH=14,DAY_OF_YEAR=14,
  DAY_OF_WEEK=4,DAY_OF_WEEK_IN_MONTH=2,AM_PM=0,HOUR=10,HOUR_OF_DAY=10,
  MINUTE=23,SECOND=36,MILLISECOND=972,ZONE_OFFSET=36000000,
  DST_OFFSET=3600000]
Default Date: Wed Jan 14 10:23:36 EST 2009
User Formatted Date: 14/01/2009 10:01:972 AM

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What are Java Operators?

Manet — Mon, 12 Jan 2009 13:02:21 +0000

In Java Language, there are 4 types of operators

Arithmetic
Relational
Logical
Bitwise

The rest of this post includes a small class to demonstrate on how those operators are used.

Arithmetic Operators

+ : Addition

- : Subtraction

* : Multiplication

/ : Division

% : Modulus

++ : Increment

-− : Decrement

Example

public class ArithmeticOperator {
 
    public static void main(String[] args) {
        int a = 2;
        int b = 100;
        int ab = a + b;
        int c = b - a;
        int d = a * b;
        int e = b/a;
        int f = b%a;
        int g = a++;
        int h = a++;
        int i = ++g;
        int j = ++g;
        int k = b--;
        int l = b--;
        int m = --l;
        int n = --l;
 
        String s = "" +
            "ab = " + ab + "n" +
            "a  = " + a + "n" +
            "b  = " + b + "n" +
            "c  = " + c + "n" +
            "d  = " + d + "n" +
            "e  = " + e + "n" +
            "f  = " + f + "n" +
            "g  = " + g + "n" +
            "h  = " + h + "n" +
            "i  = " + i + "n" +
            "j  = " + j + "n" +
            "k  = " + k + "n" +
            "l  = " + l + "n" +
            "m  = " + m + "n" +
            "n  = " + n + "n";
 
        System.out.println(s);
    }
 
}

Relational Operators

== : Equal to

!= : Not equal to

< : Less than

> : Greater than

<= : Less than or equal to

>= : Greater than or equal to

Example

public class RelationalOperator {
 
    public static void main(String[] args) {
 
        int a = 10;
        int b = 100;
 
        System.out.println("a == b : " + (a == b) );
        System.out.println("a != b : " + (a != b) );
        System.out.println("a < b  : " + (a < b) );
        System.out.println("a > b  : " + (a > b) );
        System.out.println("a <= b : " + (a <= b) );
        System.out.println("a >= b : " + (a >= b) );
    }
 
}

Logical Operators

& : Boolean AND

| : Boolean OR

! : Logical NOT

^ : Boolean XOR

|| : Logical OR

&& : Logical AND

Example

public class LogicalOperator {
 
    public static void main(String[] args) {
 
        boolean t = true;
        boolean f = false;
 
        System.out.println("t & f  : " + (t & f) );
        System.out.println("t | f  : " + (t | f) );
        System.out.println("! f    : " + (! f) );
        System.out.println("t ^ f  : " + (t ^ f) );
        System.out.println("t || f : " + (t || f) );
        System.out.println("t && f : " + (t && f) );
    }
 
}

Bitwise Operators

& : Boolean AND

| : Boolean OR

~ : Boolean NOT

^ : Boolean XOR

>> : Shift Right

<< : Shift Left

>>> : Shift Right Unsigned

Example

public class BitwiseOperator {
 
    public static void main(String[] args) {
 
        int a = 123; // 1 1 1 1 0 1 1
        int b = 321; // 1 0 1 0 0 0 0 0 1
 
        System.out.println("a & b   : " + (a & b) );
        System.out.println("a | b   : " + (a | b) );
        System.out.println("~a      : " + (~ a) );
        System.out.println("a ^ b   : " + (a ^ b) );
        System.out.println("a >> b  : " + (a >> b) );
        System.out.println("a << b  : " + (a << b) );
        System.out.println("a >>> b : " + (a >>> b) );
 
    }
 
}

Source code

operator-demo.zip

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How to include CSS Style Sheet file in HTML Document?

Manet — Sat, 27 Dec 2008 00:30:17 +0000

Here is a quick tip. Code below showing you how to include CSS Style Sheet file in to HTML document

Page Title

How to convert String to Date in SQL statement?

Manet — Wed, 24 Dec 2008 11:17:17 +0000

This is a list of handy tips that could help you in a blink on how to convert String to Date in SQL. This post cover 5 popular databases (Oracle, MySQL, DB2, PostgreSQL, Informix)

Post your comment here if you find this post useful or want to contribute more explaination.

Oracle

Syntax:

to_date(date_string, format)

Example:

SELECT user.name, user.location FROM user
WHERE user.starteddtm = to_date('20/10/2007 16:01', 'dd/mm/yyyy hh24:mi');

(more details on this function)

MySQL

Syntax:

STR_TO_DATE(date_string, format)

Example:

SELECT user.name, user.location FROM user
WHERE user.starteddtm = STR_TO_DATE('20/10/2007 16:01', '%d/%m/%Y %H:%i');

(see more details on date format)

DB2

In DB2 You can use the following function to convert a character string to a date or time value

Syntax:

TIMESTAMP(date_time_string)
DATE(date_string)
TIME(time_string)

Example:

TIMESTAMP ('2002-10-20-12.00.00.000000')
TIMESTAMP ('2002-10-20 12:00:00')
DATE ('2002-10-20')
DATE ('10/20/2002')
TIME ('12:00:00')
TIME ('12.00.00')

SELECT user.name, user.location FROM user
WHERE user.starteddtm = DATE('20/10/2007');

(more details)

PostgreSQL

Syntax:

to_date(date_string, format)

Example:

SELECT user.name, user.location FROM user
WHERE user.starteddtm = STR_TO_DATE('20/10/2007 16:01', 'DD/MM/YYYY HH24:MI');

(more details)

Informix

Syntax:

DATE(date_string)
TO_DATE(date_string, format)

Example:

SELECT user.name, user.location FROM user
WHERE user.starteddtm = DATE('20/10/2007');

SELECT user.name, user.location FROM user
WHERE user.starteddtm = TO_DATE('20/10/2007 16:00', '%d/%m/%Y %H:%M');

(more detail on these functions)

How to do Find and Replace in VBA?

Manet — Wed, 24 Dec 2008 02:24:16 +0000

If you want to automate your find and replace in MS Office Word Document
You could use or modify this Sub to suit your own needs.

Remember it only support upto 512 bytes (512 characters) of text at the time.

Sub FindReplace()
' Find and replace string in document
' Support up to 512 bytes (double size the default)
  With Selection.Find
    .ClearFormatting
    .Text = "old text"
    .Replacement.ClearFormatting
    .Replacement.Text = "new text"
    .Execute Replace:=wdReplaceAll, Forward:=True, Wrap:=wdFindContinue
  End With
End Sub

Computer FAQs & Tips » Programming

Java: How to convert String to array?

How to copy text file in Java?

Understand Java break and continue Statements

break Statement

continue Statement

How to add or display favicon on a webpage?

What is favicon?

Add favicon

Generate Random Password in Java

Use Calendar instead of Date in Java

Common Issue

Alternative

What are Java Operators?

Arithmetic Operators

Relational Operators

Logical Operators

Bitwise Operators

Source code

How to include CSS Style Sheet file in HTML Document?

How to convert String to Date in SQL statement?

Oracle

MySQL

DB2

PostgreSQL

Informix

How to do Find and Replace in VBA?

`break` Statement

`continue` Statement