🚀 Java Code Watch

A simple CLI tool to view and copy Java data structure code (like LinkedList, Stack, etc.) directly in your browser.

📦 Installation

Option 1: Use without installing (recommended)

npx javacodewatch

Option 2: Install locally

npm install chiwormjava

Run:

npx javacodewatch

Option 3: Install globally (optional)

npm install -g chiwormjava

Run:

javacodewatch

🧠 What it does

• Opens a local server
• Launches your browser
• Shows Java code snippets
• Click → View code
• Click → Copy code

📸 Features

• 📚 Java DSA snippets (LinkedList, etc.)
• 🖱️ One-click code view
• 📋 Copy to clipboard
• 🌙 Clean dark UI

▶️ Usage

After running the command:

javacodewatch

👉 Your browser will open automatically:

http://localhost:3000

Armstrong

Name: <input type="text" name="name" value="<?php echo $editData['name'] ?? ''; ?>"><br><br>
Email: <input type="text" name="email" value="<?php echo $editData['email'] ?? ''; ?>"><br><br>

<?php if($editData){ ?>
    <input type="submit" name="update" value="Update">
<?php } else { ?>
    <input type="submit" name="add" value="Add">
<?php } ?>

$img = imagecreatetruecolor(500, 350);

$white = imagecolorallocate($img, 255, 255, 255); $black = imagecolorallocate($img, 0, 0, 0); $red = imagecolorallocate($img, 255, 0, 0); $blue = imagecolorallocate($img, 0, 0, 255); $green = imagecolorallocate($img, 0, 255, 0); $yellow= imagecolorallocate($img, 255, 255, 0);

imagefill($img, 0, 0, $white);

imagerectangle($img, 20, 20, 120, 100, $black); imagefilledrectangle($img, 140, 20, 240, 100, $green);

imageellipse($img, 350, 70, 80, 80, $red); imagefilledellipse($img, 450, 70, 80, 80, $yellow);

imageline($img, 20, 150, 200, 250, $blue);

$points = [300,150, 350,250, 250,250]; imagepolygon($img, $points, 3, $black);

$points2 = [400,150, 450,250, 350,250]; imagefilledpolygon($img, $points2, 3, $red);

imagearc($img, 100, 300, 100, 50, 0, 180, $blue);

imagestring($img, 5, 180, 300, "Shapes Demo", $black);

header("Content-Type: image/png"); imagepng($img); imagedestroy($img);

1. Right Triangle

Pattern:

*
* *
* * *
* * * *
* * * * *

Code:

<?php
for($i = 1; $i <= 5; $i++){
    for($j = 1; $j <= $i; $j++){
        echo "* ";
    }
    echo "<br>";
}
?>

2. Inverted Triangle

Pattern:

* * * * *
* * * *
* * *
* *
*

Code:

<?php
for($i = 5; $i >= 1; $i--){
    for($j = 1; $j <= $i; $j++){
        echo "* ";
    }
    echo "<br>";
}
?>

3. Full Pyramid

Pattern:

    *
   ***
  *****
 *******
*********

Code:

<?php
for($i = 1; $i <= 5; $i++){
    for($j = 1; $j <= 5 - $i; $j++){
        echo "&nbsp;";
    }
    for($k = 1; $k <= (2*$i - 1); $k++){
        echo "*";
    }
    echo "<br>";
}
?>

⭐ 4. Diamond Pattern

Pattern:

    *
   ***
  *****
   ***
    *

Code:

<?php
// upper
for($i = 1; $i <= 3; $i++){
    for($j = 1; $j <= 3 - $i; $j++){
        echo "&nbsp;";
    }
    for($k = 1; $k <= (2*$i - 1); $k++){
        echo "*";
    }
    echo "<br>";
}

// lower
for($i = 2; $i >= 1; $i--){
    for($j = 1; $j <= 3 - $i; $j++){
        echo "&nbsp;";
    }
    for($k = 1; $k <= (2*$i - 1); $k++){
        echo "*";
    }
    echo "<br>";
}
?>

5. Number Triangle

Pattern:

1
1 2
1 2 3
1 2 3 4
1 2 3 4 5

Code:

<?php
for($i = 1; $i <= 5; $i++){
    for($j = 1; $j <= $i; $j++){
        echo $j . " ";
    }
    echo "<br>";
}
?>

6. Floyd’s Triangle

Pattern:

1
2 3
4 5 6
7 8 9 10

Code:

<?php
$num = 1;
for($i = 1; $i <= 4; $i++){
    for($j = 1; $j <= $i; $j++){
        echo $num . " ";
        $num++;
    }
    echo "<br>";
}
?>

7. Alphabet Pattern

Pattern:

A
A B
A B C
A B C D

Code:

<?php
for($i = 65; $i <= 68; $i++){
    for($j = 65; $j <= $i; $j++){
        echo chr($j) . " ";
    }
    echo "<br>";
}
?>

8. Hollow Square

Pattern:

* * * * *
*       *
*       *
*       *
* * * * *

Code:

<?php
$n = 5;
for($i = 1; $i <= $n; $i++){
    for($j = 1; $j <= $n; $j++){
        if($i == 1 || $i == $n || $j == 1 || $j == $n){
            echo "* ";
        } else {
            echo "&nbsp;&nbsp;";
        }
    }
    echo "<br>";
}
?>

9. Left-Aligned Triangle

Pattern:

        *
      * *
    * * *
  * * * *
* * * * *

Code:

<?php
for($i = 1; $i <= 5; $i++){
    for($j = 1; $j <= 5 - $i; $j++){
        echo "&nbsp;&nbsp;";
    }
    for($k = 1; $k <= $i; $k++){
        echo "* ";
    }
    echo "<br>";
}
?>

10. Hollow Pyramid

Pattern:

    *
   * *
  *   *
 *     *
*********

Code:

<?php
$n = 5;
for($i = 1; $i <= $n; $i++){
    for($j = 1; $j <= $n - $i; $j++){
        echo "&nbsp;&nbsp;";
    }
    for($k = 1; $k <= (2*$i - 1); $k++){
        if($k == 1 || $k == (2*$i - 1) || $i == $n){
            echo "*";
        } else {
            echo "&nbsp;";
        }
    }
    echo "<br>";
}
?>

⭐ 11. Hollow Diamond

Pattern:

    *
   * *
  *   *
   * *
    *

Code:

<?php
$n = 3;

// upper
for($i = 1; $i <= $n; $i++){
    for($j = 1; $j <= $n - $i; $j++){
        echo "&nbsp;&nbsp;";
    }
    for($k = 1; $k <= (2*$i - 1); $k++){
        if($k == 1 || $k == (2*$i - 1)){
            echo "*";
        } else {
            echo "&nbsp;";
        }
    }
    echo "<br>";
}

// lower
for($i = $n - 1; $i >= 1; $i--){
    for($j = 1; $j <= $n - $i; $j++){
        echo "&nbsp;&nbsp;";
    }
    for($k = 1; $k <= (2*$i - 1); $k++){
        if($k == 1 || $k == (2*$i - 1)){
            echo "*";
        } else {
            echo "&nbsp;";
        }
    }
    echo "<br>";
}
?>

12. Palindrome Number Pattern

Pattern:

1
121
12321
1234321

Code:

<?php
for($i = 1; $i <= 4; $i++){
    for($j = 1; $j <= $i; $j++){
        echo $j;
    }
    for($j = $i - 1; $j >= 1; $j--){
        echo $j;
    }
    echo "<br>";
}
?>

13. Pascal’s Triangle

Pattern:

1
1 1
1 2 1
1 3 3 1

Code:

<?php
$n = 5;

for($i = 0; $i < $n; $i++){
    $num = 1;
    for($j = 0; $j <= $i; $j++){
        echo $num . " ";
        $num = $num * ($i - $j) / ($j + 1);
    }
    echo "<br>";
}
?>

14. Butterfly Pattern

Pattern:

*      *
**    **
***  ***
********
***  ***
**    **
*      *

Code:

<?php
$n = 4;

// upper
for($i = 1; $i <= $n; $i++){
    for($j = 1; $j <= $i; $j++){
        echo "*";
    }
    for($j = 1; $j <= 2*($n-$i); $j++){
        echo "&nbsp;";
    }
    for($j = 1; $j <= $i; $j++){
        echo "*";
    }
    echo "<br>";
}

// lower
for($i = $n; $i >= 1; $i--){
    for($j = 1; $j <= $i; $j++){
        echo "*";
    }
    for($j = 1; $j <= 2*($n-$i); $j++){
        echo "&nbsp;";
    }
    for($j = 1; $j <= $i; $j++){
        echo "*";
    }
    echo "<br>";
}
?>

15. Reverse Alphabet Pattern

Pattern:

E
D E
C D E
B C D E
A B C D E

Code:

<?php
for($i = 69; $i >= 65; $i--){
    for($j = $i; $j <= 69; $j++){
        echo chr($j) . " ";
    }
    echo "<br>";
}
?>

1. Current Date & Time (Using date())

<?php
date_default_timezone_set("Asia/Kolkata");

echo "Current Date: " . date("Y-m-d") . "<br>";
echo "Current Time: " . date("H:i:s") . "<br>";
echo "Full Format: " . date("d-m-Y H:i:s");
?>

Common Formats

• Y → year (2026)
• m → month
• d → day
• H → hour (24 format)
• i → minutes
• s → seconds

2. Using time() (Timestamp)

<?php
date_default_timezone_set("Asia/Kolkata");

$current = time();

echo "Timestamp: " . $current . "<br>";
echo "Readable Date: " . date("d-m-Y H:i:s", $current);
?>

3. Using new DateTime() (IMPORTANT)

This is the modern and most important method.

<?php
date_default_timezone_set("Asia/Kolkata");

$date = new DateTime();

echo $date->format("d-m-Y H:i:s");
?>

4. Custom Date

<?php
$date = new DateTime("2026-04-02");

echo $date->format("d-m-Y");
?>

5. Add / Modify Date

<?php
$date = new DateTime();

$date->modify("+5 days");
echo "After 5 days: " . $date->format("d-m-Y") . "<br>";

$date->modify("+1 month");
echo "After 1 month: " . $date->format("d-m-Y");
?>

6. Date Difference (Age Calculator Logic)

<?php
date_default_timezone_set("Asia/Kolkata");

$birth = new DateTime("2006-01-03");
$current = new DateTime();

$diff = $current->diff($birth);

echo "Age: " . $diff->y . " Years ";
echo $diff->m . " Months ";
echo $diff->d . " Days";
?>

7. Compare Two Dates

<?php
$d1 = new DateTime("2026-04-01");
$d2 = new DateTime("2026-04-10");

if($d1 < $d2){
    echo "d1 is earlier";
} else {
    echo "d2 is earlier";
}
?>

Important Exam Points

• Always use:

date_default_timezone_set("Asia/Kolkata");

1. HTML Form + Display Name using PHP

<!-- form.php -->
<form method="post">
    Enter Name: <input type="text" name="username">
    <input type="submit" value="Submit">
</form>

<?php
if(isset($_POST['username'])){
    echo "Hello " . $_POST['username'];
}
?>

2. Number Programs

(a) Prime Number

<?php
$num = 7;
$flag = 1;

for($i=2; $i<$num; $i++){
    if($num % $i == 0){
        $flag = 0;
        break;
    }
}

if($flag == 1)
    echo "Prime";
else
    echo "Not Prime";
?>

(b) Odd or Even

<?php
$num = 10;

if($num % 2 == 0)
    echo "Even";
else
    echo "Odd";
?>

(c) Greatest of Three Numbers

<?php
$a = 10; $b = 25; $c = 15;

if($a >= $b && $a >= $c)
    echo "Greatest: $a";
elseif($b >= $a && $b >= $c)
    echo "Greatest: $b";
else
    echo "Greatest: $c";
?>

3. Loop Programs

(a) Reverse 10 to 1

<?php
for($i=10; $i>=1; $i--){
    echo $i . " ";
}
?>

(b) 1-2-3-...-10 (no extra hyphen)

<?php
for($i=1; $i<=10; $i++){
    if($i < 10)
        echo $i . "-";
    else
        echo $i;
}
?>

(c) Floyd Triangle

<?php
$n = 5;
$num = 1;

for($i=1; $i<=$n; $i++){
    for($j=1; $j<=$i; $j++){
        echo $num . " ";
        $num++;
    }
    echo "<br>";
}
?>

4. Continue + Arithmetic Operations

(a) Skip User Number

<?php
$skip = 5;

for($i=1; $i<=10; $i++){
    if($i == $skip)
        continue;
    echo $i . " ";
}
?>

(b) Arithmetic using Select Box

<form method="post">
    Num1: <input type="number" name="a"><br>
    Num2: <input type="number" name="b"><br>
    <select name="op">
        <option value="add">Add</option>
        <option value="sub">Subtract</option>
        <option value="mul">Multiply</option>
        <option value="div">Divide</option>
    </select>
    <input type="submit">
</form>

<?php
if(isset($_POST['op'])){
    $a = $_POST['a'];
    $b = $_POST['b'];

    if($_POST['op']=="add") echo $a+$b;
    elseif($_POST['op']=="sub") echo $a-$b;
    elseif($_POST['op']=="mul") echo $a*$b;
    elseif($_POST['op']=="div") echo $a/$b;
}
?>

5. Table + Armstrong

(a) Multiplication Table

<?php
$num = 5;

for($i=1; $i<=10; $i++){
    echo "$num x $i = " . ($num*$i) . "<br>";
}
?>

(b) Armstrong Number

<?php
$num = 153;
$sum = 0;
$temp = $num;

while($temp > 0){
    $rem = $temp % 10;
    $sum += $rem * $rem * $rem;
    $temp = (int)($temp/10);
}

if($sum == $num)
    echo "Armstrong";
else
    echo "Not Armstrong";
?>

6. Array + Table

(a) Fruit Table

<?php
$fruits = ["Apple", "Banana", "Mango"];

echo "<table border=1>";
foreach($fruits as $f){
    echo "<tr><td>$f</td></tr>";
}
echo "</table>";
?>

(b) Sum of Array

<?php
$arr = [1,2,3,4,5];
$sum = 0;

foreach($arr as $v){
    $sum += $v;
}

echo "Sum = $sum";
?>

7 & 8. Matrix + Palindrome

(a) Multiply Number with Matrix

<?php
$matrix = [
    [1,2],
    [3,4]
];

$num = 2;

for($i=0; $i<2; $i++){
    for($j=0; $j<2; $j++){
        echo $matrix[$i][$j] * $num . " ";
    }
    echo "<br>";
}
?>

(b) Palindrome String

<?php
$str = "malayalam";

if($str == strrev($str))
    echo "Palindrome";
else
    echo "Not Palindrome";
?>

9. Registration Form + Display Data

<form method="post">
    Name: <input type="text" name="name"><br>
    Email: <input type="text" name="email"><br>
    <input type="submit">
</form>

<?php
if(isset($_POST['name'])){
    echo "Name: " . $_POST['name'] . "<br>";
    echo "Email: " . $_POST['email'];
}
?>

10. Login (Username + Password Check)

<form method="post">
    Username: <input type="text" name="user"><br>
    Password: <input type="password" name="pass"><br>
    <input type="submit">
</form>

<?php
if(isset($_POST['user'])){
    if($_POST['user']=="admin" && $_POST['pass']=="godsgift"){
        echo "Welcome Admin";
    } else {
        echo "Invalid Login";
        header("refresh:2; url=");
    }
}
?>