Java Code To Search Directories Recursively For A File

Here is the Java Code to search for a file recursively through the code.

import java.io.File;
import java.util.ArrayList;
import java.util.List;

public class FileSearch {
     
     static List<String> result = new ArrayList<String>();
     
     public static void main(String[] args) {
          String dirc = "C:\\Users\\naved.alam\\workspace\\Test";
          String fName = "FileSearch.java";
          FileSearch.search(new File(dirc),fName);
          int size = result.size();
          if(size ==0){
               System.out.println("\nNo File found.");
          }else{
               System.out.println("\nFound " + size + " File:");
               for (String matched : result){
                    System.out.println("File : " + matched);
               }
          }
     }

     private static void search(File directory,String fileName) {
          if (directory.isDirectory()) {
               System.out.println("Searching directory..." + directory.getAbsoluteFile());
               //Check for permission
               if (directory.canRead()) {
                    for (File temp : directory.listFiles()) {
                         if (temp.isDirectory()) 
                              search(temp,fileName);
                         else if (fileName.equals(temp.getName()))      
                                   result.add(temp.getAbsoluteFile().toString());
                    }

               } 
               else 
                    System.out.println(directory.getAbsoluteFile() + ": Permission Denied");
          }
     }
}

A sample run is shown below:

Searching directory...C:\Users\naved.alam\workspace\Test
Searching directory...C:\Users\naved.alam\workspace\Test\.settings
Searching directory...C:\Users\naved.alam\workspace\Test\backup
Searching directory...C:\Users\naved.alam\workspace\Test\bin
Searching directory...C:\Users\naved.alam\workspace\Test\bin\com
Searching directory...C:\Users\naved.alam\workspace\Test\bin\com\example
Searching directory...C:\Users\naved.alam\workspace\Test\src
Searching directory...C:\Users\naved.alam\workspace\Test\src\com
Searching directory...C:\Users\naved.alam\workspace\Test\src\com\example

Found 2 File:
File : C:\Users\naved.alam\workspace\Test\backup\FileSearch.java
File : C:\Users\naved.alam\workspace\Test\src\com\example\FileSearch.java

Above code can be modified to search for a file matching certain pattern or expression and can be use to integrate advance file searching functionality in an application.

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android:inputType="textMultiLine"

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Two Java function can be use to calculate the elapsed time or execuiton time in java.

1. System.currentTimeMillis()
2. System.nanoTime()

Example:

System.currentTimeMillis()

 long StartTime = System.currentTimeMillis();
 //do some tasks
 long EndTime = System.currentTimeMillis();
 long difference = EndTime - StartTime;
 
 System.out.println("Elapsed milliseconds: " + difference);

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1. Java Date Examples

Few examples to work with Date APIs.

Example 1.1 – Convert Date to String.

 SimpleDateFormat sdf = new SimpleDateFormat("dd/M/yyyy");
 String date = sdf.format(new Date());
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Beginning with the equation the circle:

We can solve for 'y' in term of 'x':

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While preparing for interview, I have wasted a lot of my time on summing down the best, average and worst case complexity of different searching and sorting algorithms. To save you guys from going through same pain, I am posting my work here. So, enjoy this cheat sheet while preparing for interview. 

Searching

Algorithm	Data Structure	Time Complexity		Space Complexity
		Average	Worst	Worst
Depth First Search (DFS)	Graph of |V| vertices and |E| edges	-	O(|E| + |V|)	O(|V|)
Breadth First Search (BFS)	Graph of |V| vertices and |E| edges	-	O(|E| + |V|)	O(|V|)
Binary search	Sorted array of n elements	O(log(n))	O(log(n))	O(1)
Linear (Brute Force)	Array	O(n)	O(n)	O(1)

Always include the header files when using some standard C libraries

Yesterday, I was working on a C code of mine when I  came across a very peculiar problem. I even wrote a test code to regenerate the problem I was facing.

int main()
{
    char str[10]="3.5";
    printf("%lf",atof(str));
    return 0;
}

This is a simple code I am testing at ideone.com. I am getting the output as