Java In Practice

Finally, I can put my time into learning Java for real.

• Access the root of the codebase from here
• Learning the basic program problems from gfg/basic-programming-problems
• Feel free to visit my portfolio from itvidhanreddy.vercel.app
• Follow me on LinkedIn: in/AVidhanR

The Below codes, sure are handy

// if return type is List<Integer>
return Arrays.asList(a, b);

I'm lazy, so I did this

import java.util.Arrays;
// gives the sum!
int s = Arrays.stream(array).sum();

In 2D matrix, the below code is handy

// for traversing and other element level operations
for (int[] rows : matrix) {
    for (int ele : rows) {
        sum += ele;
    }
}

While using String's as char's the below code is handy,

for (char c : v.toCharArray()) {
    // something here...    
}

Find lengths

To find the length of an array,

int[] arr = new int[] {10, 11, 12, 13};
int lengthOfArray = arr.length;

To find the length of a number,

int n = 1234;
int l = String.valueOf(n).length(); // 4

Typical git-cli

git initial process

git init -b main
# to check the logs
git log

The after-math,

git add . && git commit -m "" && git push
# skip staging or adding and directly commit
git commit -a -m "message"
# changes made?
git diff
# rm the env from git if staged
git rm --cached env

Fetch the latest changes from the remote repository,

git fetch origin
git pull origin main

Check the below code,

// I ain't understood a thing in the below code
for (int t = n; t > 0; t /= 2) {
    b = (t % 2) + b;
}

// so I used the below abstract method
return Integer.toBinaryString(num);

Well, if you want to return int values as an array of int: the below code is handy,

return new int[] {1, 2, 3}; // or {a, b, c} if they have data in it.

The find command

• The find command in Bash is a powerful tool for searching and locating files and directories based on various conditions. Here's a comprehensive overview: Basic Syntax,

find [options] [path] [expression]

Options

• -name: Search by file name
• -iname: Search by file name (case-insensitive)
• -type: Search by file type (e.g., f for files, d for directories)
• -size: Search by file size
• -mtime: Search by modification time
• -atime: Search by access time
• -ctime: Search by creation time
• -exec: Execute a command on the found files
• -ok: Similar to -exec, but prompts for confirmation before executing

Expressions

• -a: Logical AND operator
• -o: Logical OR operator
• !: Logical NOT operator

Examples

• Find files by name: find . -name "example.txt"
• Find files by type: find . -type f -name "*.txt"
• Find files larger than 1MB: find . -size +1M
• Find files modified within the last 24 hours: find . -mtime -1
• Delete files older than 30 days: find . -type f -mtime +30 -delete
• Execute a command on found files: find . -type f -name "*.txt" -exec cat {} ;

Tips and Tricks

• Use . to search in the current directory and its subdirectories.
• Use ~ to search in the user's home directory.
• Use ! to negate a condition (e.g., ! -name "*.txt").
• Use parentheses to group conditions (e.g., ( -name ".txt" -o -name ".pdf" )).
• Use -print to print the found files (default behavior).
• Use -exec with {} ; to execute a command on each found file.

bash is a lifesaver

Bash Script is a lifesaver for lazy people like myself,

bash ./StartUpProcess.sh
# removes all the existing .class files and fetches the data from github on latest changes