Convert Layout View to Image and Store in Storage (Android)

This code able to convert the whole view in scrollview to images. It been tested and successfully working.

 

First image is from the mobile, after click the "save and print receipt" it will save the whole view and stored in image gallery. Second image is the result

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@BindView(R.id.native_resit)
protected ScrollView native_resit;


@Override
    public void onViewCreated(View view, Bundle savedInstanceState) {
        super.onViewCreated(view, savedInstanceState);

        ....
        ....

        close_btn.setOnClickListener(new resitClickListener());
        print_resit.setOnClickListener(new resitClickListener());

        runRecieptData();
}

private class resitClickListener implements View.OnClickListener{
        @Override
        public void onClick(View view) {
            if (view.getId() == R.id.close_btn){
                getFragmentManager().popBackStack();
            }
            else if (view.getId() == R.id.print_resit){
                print();
            }
        }
}

private void print(){
        ProgressDialog dialog = new ProgressDialog(getActivity());
        dialog.setMessage("Saving...");
        dialog.show();

        Bitmap bitmap = getBitmapFromView(native_resit,native_resit.getChildAt(0).getHeight(),native_resit.getChildAt(0).getWidth());
        try {
            File defaultFile = new File(Environment.getExternalStorageDirectory().getAbsolutePath()+"/Your_Folder");
            if (!defaultFile.exists())
                defaultFile.mkdirs();

            String filename = "Order ID "+orderHistoryResponse.getOrderId()+".jpg";
            File file = new File(defaultFile,filename);
            if (file.exists()) {
                file.delete();
                file = new File(defaultFile,filename);
            }

            FileOutputStream output = new FileOutputStream(file);
            bitmap.compress(Bitmap.CompressFormat.PNG, 100, output);
            output.flush();
            output.close();

            dialog.dismiss();

            Toast.makeText(getActivity(), Message.RECEIPT_SAVE, Toast.LENGTH_SHORT).show();
        } catch (Exception e) {
            e.printStackTrace();
            dialog.dismiss();
            Toast.makeText(getActivity(), Message.RECEIPT_SAVE_FAILED, Toast.LENGTH_SHORT).show();
        }
    }

    //create bitmap from the view
    private Bitmap getBitmapFromView(View view,int height,int width) {
        Bitmap bitmap = Bitmap.createBitmap(width, height,Bitmap.Config.ARGB_8888);
        Canvas canvas = new Canvas(bitmap);
        Drawable bgDrawable =view.getBackground();
        if (bgDrawable!=null)
            bgDrawable.draw(canvas);
        else
            canvas.drawColor(Color.WHITE);
        view.draw(canvas);
        return bitmap;
    } 

 

Android Viewpager Wait Fragment Finish Load

After several attempt on how to wait all the fragment in view pager is loaded, i came out a solution where i create interface class to communicate between activity and the fragment..

1. Create Interface Class
2. Implement it on Activity class
3. Call it from each fragment at the off each process

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Create Interface as bridge between fragment and activity

public interface OnFragmentFinishLoad {
    public void onFinish(String tag,boolean state);
}
 

Now Create Activity Class contain Viewpager.. (Code not complete)

public class PizzaActivity extends BaseActivity implements OnFragmentFinishLoad {

   @BindView(R.id.cover_rl)
 
   protected RelativeLayout cover_rl;

   int countLoad = 0;

   @Override
 public void onCreate(Bundle savedInstanceState) {

      super.onCreate(savedInstanceState);

      setContentView(R.layout.activity_carte_tab_layout);
      cover_rl.setVisibility(View.VISIBLE);


      setupViewPager(viewPager);

      mTabLayout.setupWithViewPager(viewPager);

      setupTabLayout(mTabLayout);

      ……
   }

   @Override
 public void onFinish(String tag, boolean state) {

      if (state)
 
         countLoad++;

      
      //cat.size() is the number of fragment in view pager.
      //each time fragment trigger this function, there will return true and countLoad will increase
      //if number of true == cat.size() the loading will disappear
  

      if (countLoad == cat.size() - 1) {

         cover_rl.setVisibility(View.GONE);

      }

   }
}
 

Then, Create Fragment class, 

public class PizzaFragment extends BaseFragment {

   @Override
 
   public View onCreateView(LayoutInflater inflater, ViewGroup container, Bundle savedInstanceState) {

      return inflater.inflate(R.layout.default_fragment, container, false);

   }

   @Override
 
   public void onViewCreated(View view, Bundle savedInstanceState) {

       super.onViewCreated(view, savedInstanceState);

       ...
       ...

       
       //run task
       new AsyncDataTaskPizza().execute();
   }

   private class AsyncDataTaskPizza extends AsyncTask < Void, Void, Void > {
      @Override
 
      protected void onPreExecute() {

         super.onPreExecute();

      }

      @Override
      protected Void doInBackground(Void... params) {
           //HTTP Call or else
      }

      @Override
 
      protected void onPostExecute(List < PizzaDetail > result) {

          // call this function after finish load everything
          ((OnFragmentFinishLoad) getActivity()).onFinish(null, true);

      }
   }

}

Create other Fragment class, do like the same or something else but last process must end with ((OnFragmentFinishLoad) getActivity()).onFinish(null, true);


This is how i manage and i found that more easier to listen when all fragment in ViewPager is finish loading.  :D

Circle of Numbers (CodeFIght)

Consider integer numbers from 0 to n - 1 written down along the circle in such a way that the distance between any two neighbouring numbers is equal (note that 0 and n - 1 are neighbouring, too).

Given n and firstNumber, find the number which is written in the radially opposite position tofirstNumber.

Example

For n = 10 and firstNumber = 2, the output should be

circleOfNumbers(n, firstNumber) = 7.

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int circleOfNumbers(int n, int firstNumber) {
    return (firstNumber+(n/2)) % n;
}
 

CPROM 2016 Q10 Adding Hexadecimal Number

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import java.util.*;

/**
   Author : Hafiq
   Date :
**/

public class HexaDec{
   public static void main(String[] args){
      Scanner scan = new Scanner(System.in);
      String line = System.getProperty("line.separator");
      scan.useDelimiter(line);
      
      int cases = scan.nextInt();
      
      for(int x=0;x<cases;x++){
         String[] split = scan.next().split(" ");
         
         int one = Integer.parseInt(split[0],16);
         int two = Integer.parseInt(split[1],16);
         
         System.out.println(Integer.toHexString(one+two).toUpperCase());
  
      }
      
   }
} 
 

CPROM 2016 Q9 SERIES OF NUMBERS

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import java.util.*;


/**
   Author : Hafiq
   Date :
**/

public class NoPlate{

   public static void main(String[] args){
      Scanner scan = new Scanner(System.in);
      
      String in = scan.next();
      
      String[] split = in.split("(?<=\\D)(?=\\d)");
      
      int num = Integer.parseInt(split[1]);
      boolean tukar = false;
      String cur = split[0];
      
      for(int x=0;x<5;x++){
         num += 1;
         if(num > 9999){
            num = 1;
            tukar = true;
         }
         else
            tukar = false;
         
         int count = 0;   
         if(tukar){
            int z=0;
            while(true){
               if(cur.equals(plateStr(z))){
                  count = z;
                  break;
               }
               z++;
            }
            
            cur = plateStr(count+1);
         }
         
         System.out.println(cur+""+num);        
      }
   }
   
   static String plateStr(int x) {
      return x < 0?"":plateStr((x / 26) - 1) + (char)(65 + x % 26);
   }
   
   
   //ZZ9997
   //ZZ9998
   //ZZ9999
   //AAA1
   //AAA2
} 
 

CPROM 2016 Q8 LEXICOGRAPHIC ORDERING

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import java.util.*;


/**
   Author : Hafiq
   Date :
**/

public class Lexi{
   public static void main(String[] args){
      Scanner scan = new Scanner(System.in);
      String line = System.getProperty("line.separator");
      scan.useDelimiter(line);
      
      int cases = scan.nextInt();
      String[] list = new String[cases];
      for(int x=0;x<cases;x++){
         list[x] = scan.next();
      }
      
      Arrays.sort(list);
      
      for(String ls:list)
         System.out.println(ls);
  }
  
} 
 

CPROM 2016 Q7 Simple Average And Median

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import java.util.*;


/**
   Author : Hafiq
   Date :
**/

public class Aveg{
   public static void main(String[] args){
      Scanner scan = new Scanner(System.in);
      String line = System.getProperty("line.separator");
      scan.useDelimiter(line);
      
      int cases = scan.nextInt();
      
      for(int x=0;x<cases;x++){
         int count = scan.nextInt();
         String[] split = scan.next().split(" ");
         int [] num = new int[count];
         for(int z=0;z<count;z++){
            num[z] = Integer.parseInt(split[z]);
         }
         Arrays.sort(num);
         
         int median = 0;double mean = 0;
         int mid = count/2;
         
         if(count%2 == 0)
            median = (num[mid-1]+num[mid]) / 2;
         else
            median = num[mid];
                     
         for(int y=0;y<count;y++){
            mean += num[y];
         }
         
         System.out.println("Average:"+mean/count+" Median:"+median);
         
      }
   }
} 
 

CPROM 2016 Q6 Title Case

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import java.util.*;


/**
   Author : Hafiq
   Date :
**/

public class TitleCase{
   public static void main(String[] args){
      Scanner scan = new Scanner(System.in);
      String line = System.getProperty("line.separator");
      scan.useDelimiter(line);
      int cases = scan.nextInt();
      
      for(int x=0;x<cases;x++){
         String[] split = scan.next().split(" ");
         
         String temp = "";
         for(int y=0;y<split.length;y++){
            temp += (""+split[y].charAt(0)).toUpperCase() + split[y].substring(1,split[y].length());
            if(y<=split.length-1){
               temp+=" ";
            }
         }
         
         System.out.println(temp);
      }
   
   }
} 
 

CPROM 2016 Q5 Encryption

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import java.util.*;


/**
   Author : Hafiq
   Date :
**/

public class Encryption{

   public static void main(String[] args){
      Scanner scan = new Scanner(System.in);
      String input = scan.nextLine();
      
      String temp = "";
      int count = 1;
      for(int x=0;x<input.length();x++){
         char a = input.charAt(x);
         
         if(a == ' '){
            temp += (char)(a+count);
            count++;
         }
         else{
            temp += (char)(a+2);
         }
      }
      
      System.out.println(temp);
   
   }
} 
 

CPROM 2016 Q4 Pair Isograms

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import java.util.*;

/**
   Author : Hafiq
   Date :
**/

public class PairIsoGram{
   public static void main(String[] args){
      Scanner scan = new Scanner(System.in);
      String line = System.getProperty("line.separator");
      scan.useDelimiter(line);
      
      int cases = scan.nextInt();
      
      for(int x=0;x<cases;x++){
         String input = scan.next();
         Map<Character, Integer> count = new HashMap<Character, Integer>();
         for(int y=0;y<input.length();y++){
            char c = input.charAt(y);
            if (count.containsKey(c)) {
                int cnt = count.get(c);
                count.put(c, ++cnt);
            } else {
                count.put(c, 1);
            }
         }        
         boolean flag = true;
         for(Map.Entry<Character, Integer> entry : count.entrySet()){
            if(entry.getValue() != 2){
               flag = false;
               break;
            }
         }         
         System.out.println(input+" --- "+ ((flag)?"pair program":"not pair isogram"));
      }       
   }
}

CPROM 2016 Q3 Find The Winner

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import java.util.*;


/**
   Author : Hafiq
   Date :
**/

public class Winner{
   public static void main(String[] args){
      Scanner scan = new Scanner(System.in);
      String line = System.getProperty("line.separator");
      scan.useDelimiter(line);
      
      int cases = scan.nextInt();
      
      int max = 0;
      String current = "";
      Event ev = new Event();
      List event = new ArrayList<>();
      for(int x=0;x(){
         @Override
         public int compare(Event e1,Event e2){
            if (e1.gold > e2.gold) {
               return -1;
            } else if (e1.gold < e2.gold) {
               return 1;
            } else {
               return 0;
            }
         }
      });
      
       
      for(Event e:event){
         System.out.println(e.toString());
      }
   }
}

class Event{
      public String name;
      public int gold;
      public int silver;
      public int bronze;
      
      public Event(){}
      
      public Event(String a,int b,int c, int d){
          name = a;
          gold = b;
          silver = c;
          bronze = d;
      }
      
      public String toString(){
         return name+" "+gold+" "+silver+" "+bronze;
      }
   }
 

CPROM2016 Q2 Split And Count

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import java.util.*;
/**
   Author : Hafiq
   Date :
**/
public class splitString{
   public static void main(String[] args){
      Scanner scan = new Scanner(System.in);
      String[] input = scan.nextLine().split("[\\s@&.;$?+-]+");
      System.out.println("Substrings length:"+input.length);
      for(int x=0;x<input.length;x++){
         System.out.println("Str["+x+"]"+input[x]+" Length:"+input[x].length());
      }
   }
}
	

CPROM2016 Q1 Multiplication Table

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import java.util.*;
/**
   Author : Hafiq
   Date :
**/
public class multiplicationTable{
   public static void main(String[] args){
      Scanner scan = new Scanner(System.in);
      int input = scan.nextInt();
      for(int x=1;x<=12;x++){
         System.out.println(x+"*"+input+"="+(x*input));
      }
   }
}
 

(Android) Simple tablayout hacky trick to custom text, background and etc

 

 

Above images is where is tried to custom the tablayout to become the shape like that :D The designer design the UI like that and i have to came out a solution to custom it..
Note: I create it by my own. If you have better solution, you can suggest me :D TQ..

Below is the base init to custom tab layout

        Tablayout tabs = (TabLayout)findViewById(R.id.tabs);
        //cast the selected tablayout to viewgroup
        ViewGroup vg = (ViewGroup) tabs.getChildAt(0);
        //count how many tabs in tablayout
        int tabsCount = vg.getChildCount();
        //iterative each tab
        for (int j = 0; j < tabsCount; j++) {
            //Get all element in each tabs and cast to viewgroup
            ViewGroup vgTab = (ViewGroup) vg.getChildAt(j);
            //count the element in each tabs
            int tabChildsCount = vgTab.getChildCount();
            for (int i = 0; i < tabChildsCount; i++) {
                // cast to View
                View tabViewChild = vgTab.getChildAt(i);
            }
        }

How to use
To change the font of the tabs. Just use View instanceOf TextView

        // using built-in tablayout function to change indicator and text color but limited
        tabs.setTabTextColors(ContextCompat.getColor(this, R.color.md_grey_500), ContextCompat.getColor(this, R.color.white));
        tabs.setSelectedTabIndicatorColor(getResources().getColor(android.R.color.transparent));

Custom Tabs

        // init your font
        Typeface tf = Typeface.createFromAsset(getAssets(), "fonts/knockout-htf49-liteweight.ttf");
        ViewGroup vg = (ViewGroup) tabs.getChildAt(0);
        int tabsCount = vg.getChildCount();
        for (int j = 0; j < tabsCount; j++) {
            ViewGroup vgTab = (ViewGroup) vg.getChildAt(j);
            int tabChildsCount = vgTab.getChildCount();
            for (int i = 0; i < tabChildsCount; i++) {
                View tabViewChild = vgTab.getChildAt(i);
                // Get TextView Element
                if (tabViewChild instanceof TextView) {
                  // change font
                  ((TextView) tabViewChild).setTypeface(tf);
                  // change color
                  ((TextView) tabViewChild).setTextColor(getResources().getColor(R.color.white));
                  // change size
                  ((TextView) tabViewChild).setTextSize(18);
                  // change padding
                  tabViewChild.setPadding(0, 0, 0, 0);
                  //..... etc...
                }
            }
        }

To change background of the tabs

        ViewGroup vg = (ViewGroup) tabs.getChildAt(0);
        int tabsCount = vg.getChildCount();
        for (int j = 0; j < tabsCount; j++) {
            View view = vg.getChildAt(j);
            //change drawable for each tabs
            view.setBackgroundResource(R.drawable.backgroundtabs);

            //if you want to diff drawable for each tabs for example tabs is 4
            //if j == 0    view.setBackgroundResource(R.drawable.backgroundtabs1);  
            //if j == 1    view.setBackgroundResource(R.drawable.backgroundtabs2);
            //if j == 2    view.setBackgroundResource(R.drawable.backgroundtabs3);
            //if j == 3    view.setBackgroundResource(R.drawable.backgroundtabs4);

            ViewGroup vgTab = (ViewGroup) view;
            int tabChildsCount = vgTab.getChildCount();
            for (int i = 0; i < tabChildsCount; i++) {
                View tabViewChild = vgTab.getChildAt(i);
            }
        }

Add listener if you want to track the tab changes

tabs.setOnTabSelectedListener(new TabLayout.OnTabSelectedListener() {
            @Override
            public void onTabSelected(TabLayout.Tab tab) {
                // code what happen when tab is selected  
            }
            @Override
            public void onTabUnselected(TabLayout.Tab tab) {
                // code what happen when tab is unselected
            }
            @Override
            public void onTabReselected(TabLayout.Tab tab) {
                // code what happen when the tab is reselected
            }
        });

To change background of the tablayout

        <android.support.design.widget.TabLayout
          android:layout_height="wrap_content"
          android:layout_width="match_parent"
          android:id="@+id/tabs"
          android:background="@drawable/stripetab"    <-- create stripe background like example image
          app:tabTextAppearance="@style/CustomTabStyle"/>

NOTES
if you want to use scrollable mode ...etc, You need to set the tabs size (i dont know why). If not, it will looks ugly

My case: i hardcode the width to 120dp (you can change it or just calculate by your own for your perfect size)

       int width = 120; // width - width of tabs 
       int tabsize = 120 * tabcount; // tabcount - number of tabs
       ViewGroup vgTab = (ViewGroup) vg.getChildAt(j);
       if (sizeScreen() < tabsize) 
           vgTab.getLayoutParams().width = dpToPx(120);

       public int dpToPx(int dp) {
           DisplayMetrics displayMetrics = getResources().getDisplayMetrics();
           return Math.round(dp * (displayMetrics.xdpi / DisplayMetrics.DENSITY_DEFAULT));
       }

       public int sizeScreen(){
           return (int)((Resources.getSystem().getDisplayMetrics().widthPixels)/ Resources.getSystem().getDisplayMetrics().density);
       }

This is example of what im doing

    private void setupTabLayout(final TabLayout tabs) {
        tabs.setTabTextColors(ContextCompat.getColor(this, R.color.md_grey_500), ContextCompat.getColor(this, R.color.white));
        tabs.setSelectedTabIndicatorColor(getResources().getColor(android.R.color.transparent));

        if (sizeScreen()<tabsize){
            tabs.setTabMode(TabLayout.MODE_SCROLLABLE);
            tabs.setTabGravity(TabLayout.GRAVITY_FILL);
        }
        else{
            tabs.setTabMode(TabLayout.MODE_FIXED);
            tabs.setTabGravity(TabLayout.GRAVITY_FILL);
        }

        // CHANGE TAB TEXT FONT
        Typeface tf = Typeface.createFromAsset(getAssets(), "fonts/knockout-htf49-liteweight.ttf");
        ViewGroup vg = (ViewGroup) tabs.getChildAt(0);
        int tabsCount = vg.getChildCount();
        for (int j = 0; j < tabsCount; j++) {
            ViewGroup vgTab = (ViewGroup) vg.getChildAt(j);

            if (j==0){
                View view = vg.getChildAt(j);
                view.setBackgroundResource(R.drawable.backgroundtabs);
            }

            if (sizeScreen()<tabsize) {
                vgTab.getLayoutParams().width = dpToPx(120);
            }

            int tabChildsCount = vgTab.getChildCount();
            for (int i = 0; i < tabChildsCount; i++) {
                View tabViewChild = vgTab.getChildAt(i);
                if (tabViewChild instanceof TextView) {
                    ((TextView) tabViewChild).setTypeface(tf);
                    ((TextView) tabViewChild).setTextSize(18);
                    ((TextView) tabViewChild).setAllCaps(true);
                    ((TextView) tabViewChild).setSingleLine(true);
                    //set the text to marquee if text longer than tabs size
                    ((TextView) tabViewChild).setEllipsize(TextUtils.TruncateAt.MARQUEE);
                    ((TextView) tabViewChild).setMarqueeRepeatLimit(100);
                    if (j==0){
                        tabViewChild.setPadding(0, 0, 0, 0);
                    }
                    else {
                        tabViewChild.setPadding(0, padding, 0, 0);
                    }
                }
            }
        }

        // add listener when tab is change
        tabs.setOnTabSelectedListener(new TabLayout.OnTabSelectedListener() {
            ViewGroup vg = (ViewGroup) tabs.getChildAt(0);

            @Override
            public void onTabSelected(TabLayout.Tab tab) {
                ViewGroup vgTab = (ViewGroup) vg.getChildAt(tab.getPosition());
                if (tab.getPosition()==0)
                    vg.getChildAt(tab.getPosition()).setBackgroundResource(R.drawable.backgroundtabs);

                else if (tab.getPosition()==tabcount-1)
                    vg.getChildAt(tab.getPosition()).setBackgroundResource(R.drawable.backgroundtabs_last);

                else
                    vg.getChildAt(tab.getPosition()).setBackgroundResource(R.drawable.backgroundtabs_middle);

                int tabChildsCount = vgTab.getChildCount();
                for (int i = 0; i < tabChildsCount; i++) {
                    View tabViewChild = vgTab.getChildAt(i);
                    if (tabViewChild instanceof TextView) {
                        tabViewChild.setPadding(0, 0, 0, 0);
                    }
                }
                viewPager.setCurrentItem(tab.getPosition());
            }

            @Override
            public void onTabUnselected(TabLayout.Tab tab) {
                ViewGroup vgTab = (ViewGroup) vg.getChildAt(tab.getPosition());
                vg.getChildAt(tab.getPosition()).setBackgroundResource(0);
                int tabChildsCount = vgTab.getChildCount();
                for (int i = 0; i < tabChildsCount; i++) {
                    View tabViewChild = vgTab.getChildAt(i);
                    if (tabViewChild instanceof TextView) {
                        tabViewChild.setPadding(0, padding, 0, 0);
                    }
                }
            }

            @Override
            public void onTabReselected(TabLayout.Tab tab) {

            }
        });
    }

Easy way to find Duplicate character in String Java

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    private static boolean findDuplicate(String str){

        Map map = new HashMap<>();
        char[] getChar = str.toCharArray();
        for(Character isDuplicate:getChar){
            if(map.containsKey(isDuplicate)){
               // plus 1 if found same character     
               map.put(isDuplicate, map.get(isDuplicate)+1);
            } else {
               // add 1 to new Character
               map.put(isDuplicate, 1);
            }
        }
        Set keys = map.keySet();
        for(Character isDuplicate:keys){
            if(map.get(isDuplicate) > 1){
                //found more than 1
                return true;
            }
        }

        return false;
    }

  

Autokey Cipher

Autokey encryption and decryption

Plaint text = "FOLLOWDIRECTION"
Autokey = P

This Autokey is polyalphabet Substitution cipher. In this cipher, the key is a stream of subkeys which is each subkey is used to encrypt the corresponding character in the plaintext.

For example

Plaintext --> F O L L O W D I R E C T I O N
Key       --> P F O L L O W D I R E C T I O

As shown, the key is add the first of subkeys.

Lets Encrypt

              F O L L O W D I R E C T I O N
              P F O L L O W D I R E C T I O
              -----------------------------
          (+) U T Z W Z K Z L Z V G V B W B
              -----------------------------
  
 * can use vigenere table to calculate

Lets Decrypt

Put the key first

              P
              -----------------------------
              U T Z W Z K Z L Z V G V B W B
              -----------------------------
              
Do subtraction cipher - key. ex: U - P = F . Add F plaintext letter to the end of the keystream.

              F
              P F
              -----------------------------
              U T Z W Z K Z L Z V G V B W B
              -----------------------------

Do subtraction cipher - key. ex: T - F = O . Again add O plaintext letter to the end of the keystream.

              F O
              P F O
              -----------------------------
              U T Z W Z K Z L Z V G V B W B
              -----------------------------
 
              F O L
              P F O L
              -----------------------------
              U T Z W Z K Z L Z V G V B W B
              -----------------------------

              F O L L
              P F O L L
              -----------------------------
              U T Z W Z K Z L Z V G V B W B
              -----------------------------

continue subtraction until

              F O L L O W D I R E C T I O N
              P F O L L O W D I R E C T I O
              -----------------------------
              U T Z W Z K Z L Z V G V B W B
              -----------------------------

DONE!

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/*
   Autokey encryption and decryption
*/
import java.util.*;
import java.lang.*;
import java.math.*;

public class Autokey{
   private static String alpha = "ABCDEFGHIJKLMNOPQRSTUVWXYZ";
   
   public static void main(String[] args){
      String text = "FOLLOWDIRECTION";
      String key = "P";  //15 - P
      
      if(key.matches("[-+]?\\d*\\.?\\d+"))
         key = ""+alpha.charAt(Integer.parseInt(key));
         
      String enc = AutoEncryption(text,key);
      System.out.println("Plaintext : "+text);
      System.out.println("Encrypted : "+enc);
      System.out.println("Decrypted : "+AutoDecryption(enc,key));

   }
   
   public static String AutoEncryption(String text,String key){
      int len = text.length();
      
      String subkey = key + text;
      subkey = subkey.substring(0,subkey.length()-key.length());
      
      String sb = "";
      for(int x=0;x<len;x++){
         int get1 = alpha.indexOf(text.charAt(x));
         int get2 = alpha.indexOf(subkey.charAt(x));
         
         int total = (get1 + get2)%26;
         
         sb += alpha.charAt(total);
      }
     
      return sb;   
   }
   
   public static String AutoDecryption(String text,String key){
      int len = text.length();
      
      String current = key;
      String sb ="";
      
      for(int x=0;x<len;x++){
         int get1 = alpha.indexOf(text.charAt(x));
         int get2 = alpha.indexOf(current.charAt(x));
         
         int total = (get1 - get2)%26;
         total = (total<0)? total + 26 : total;
         sb += alpha.charAt(total);
         
         current += alpha.charAt(total);
      }
      return sb;
   }
}

Find the Closest Pair of Coordinate using Brute Force and Divide n Conquer

We are given an array of n points , and the problem is to find out the closest pair of points in the array. This problem arises in a number of applications. For example, in air-traffic control, you may want to monitor planes that come too close together, since this may indicate a possible collision. Recall the following formula for distance between two points p and q.

The Brute force solution is O(n^2), compute the distance between each pair and return the smallest. For faster solution to find smallest distance in O(nLogn) time using Divide and Conquer strategy.

In this case, Brute force produce must faster if the list of Coordinate we want to compare is less than 50.

But,

Divide and Conquer strategy can process large amount > 50 of list more faster than brute force.

This is the time execution for both method

1000 list
Brute force (462 ms)
Divide and conquer (56 ms)

500 list
Brute force (147 ms)
Divide and conquer (14 ms)

100 list
Brute force (10 ms)
Divide and conquer (8 ms)

50 list
Brute force (3 ms)
Divide and conquer (5 ms)

10 list
Brute force (1 ms)
Divide and conquer (3 ms)

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import java.io.*;
import java.util.*;

public class ClosestCoorFinder {
    public static void main(String[] args) {
        Scanner scan = new Scanner(System.in);
        String line = System.getProperty("line.separator");
        scan.useDelimiter(line);

        List<Coordinate> points = new ArrayList<>();
        Random random = new Random();
        for (int x=0;x<1000;x++){
            points.add(new Coordinate(random.nextInt(),random.nextInt()));
        }


        long startTime = System.currentTimeMillis();
        CoordinateDetail bruteForceClosestPair = bruteForce(points);
        long elapsedTime = System.currentTimeMillis() - startTime;
        System.out.println("Brute force (" + elapsedTime + " ms): " + bruteForceClosestPair);
        startTime = System.currentTimeMillis();
        CoordinateDetail dqClosestPair = divideAndConquer(points);
        elapsedTime = System.currentTimeMillis() - startTime;
        System.out.println("Divide and conquer (" + elapsedTime + " ms): " + dqClosestPair);
    }


    private static class Coordinate {
        private double x;
        private double y;

        public Coordinate(int id, double x, double y) {
            this.id = id;
            this.x = x;
            this.y = y;
        }

        public int getId() {
            return id;
        }

        public double getX() {
            return x;
        }

        public double getY() {
            return y;
        }

        public String toString() {
            return "(" + x + ", " + y +")";
        }
    }

    private static class CoordinateDetail {
        private Coordinate point1 = null;
        private Coordinate point2 = null;
        private double distance = 0.0;

        public CoordinateDetail(Coordinate point1, Coordinate point2, double distance) {
            this.point1 = point1;
            this.point2 = point2;
            this.distance = distance;
        }

        public Coordinate getPoint1() {
            return point1;
        }

        public Coordinate getPoint2() {
            return point2;
        }


        public double getDistance() {
            return distance;
        }


        public void set(Coordinate point1, Coordinate point2, double distance) {
            this.point1 = point1;
            this.point2 = point2;
            this.distance = distance;
        }

        public String toString() {
            return getPoint1() +" "+getPoint2()+" : distance = "+getDistance();
        }
    }

    private static double calDistance(Coordinate p1, Coordinate p2) {
        double xdist = p2.getX() - p1.getX();
        double ydist = p2.getY() - p1.getY();
        return Math.hypot(xdist, ydist);
    }

    // much faster than DnV for list of Coordinate is less than 100
    private static CoordinateDetail bruteForce(List<Coordinate> points) {
        int coorSize = points.size();
        if (coorSize < 2)
            return null;

        CoordinateDetail coorPoint = new CoordinateDetail(points.get(0), points.get(1),calDistance(points.get(0), points.get(1)));
        if (coorSize > 2) {
            for (int i = 0; i < coorSize - 1; i++) {
                Coordinate point1 = points.get(i);
                for (int j = i + 1; j < coorSize; j++) {
                    Coordinate point2 = points.get(j);
                    double distance = calDistance(point1, point2);
                    if (distance < coorPoint.getDistance())
                        coorPoint.set(point1, point2, distance);
                }
            }
        }
        return coorPoint;
    }

    private static void sortByX(List<Coordinate> points) {
        Collections.sort(points, new Comparator < Coordinate > () {
            public int compare(Coordinate point1, Coordinate point2) {
                if (point1.getX() < point2.getX())
                    return -1;
                if (point1.getX() > point2.getX())
                    return 1;
                return 0;
            }
        });
    }

    private static void sortByY(List<Coordinate> points) {
        Collections.sort(points, new Comparator <Coordinate> () {
            public int compare(Coordinate point1, Coordinate point2) {
                if (point1.getY() < point2.getY())
                    return -1;
                if (point1.getY() > point2.getY())
                    return 1;
                return 0;
            }
        });
    }

    // much faster than bruteforce for list of Coordinate is more than 100
    public static CoordinateDetail divideAndConquer(List<Coordinate> points) {
        List<Coordinate> listofSortedX = new ArrayList<> (points);
        sortByX(listofSortedX);
        List<Coordinate> listofSortedY = new ArrayList<> (points);
        sortByY(listofSortedY);
        return divideAndConquer(listofSortedX, listofSortedY);
    }

    private static CoordinateDetail divideAndConquer(List<Coordinate> listofSortedX, List<Coordinate> listofSortedY) {
        int coorSize = listofSortedX.size();
        if (coorSize <= 3)
            return bruteForce(listofSortedX);

        int index = coorSize >>> 1;
        List<Coordinate>leftOfCenter = listofSortedX.subList(0, index);
        List<Coordinate>rightOfCenter = listofSortedX.subList(index, coorSize);

        List<Coordinate>tempList= new ArrayList<>(leftOfCenter);
        sortByY(tempList);

        CoordinateDetail closestPair = divideAndConquer(leftOfCenter, tempList);

        tempList.clear();

        tempList.addAll(rightOfCenter);
        sortByY(tempList);

        CoordinateDetail closestPairRight = divideAndConquer(rightOfCenter, tempList);

        if (closestPairRight.getDistance() < closestPair.getDistance())
            closestPair = closestPairRight;

        tempList.clear();

        double shortestDistance = closestPair.getDistance();
        double centerX = rightOfCenter.get(0).getX();
        for (Coordinate point: listofSortedY)
            if (Math.abs(centerX - point.getX()) < shortestDistance)
                tempList.add(point);

        for (int i=0; i<tempList.size()-1;i++) {
            Coordinate point1 = tempList.get(i);
            for (int j=i+1;j<tempList.size();j++) {
                Coordinate point2 = tempList.get(j);
                if ((point2.getY() - point1.getY()) >= shortestDistance)
                    break;
                double distance = calDistance(point1, point2);
                if (distance < closestPair.getDistance()) {
                    closestPair.set(point1, point2, distance);
                    shortestDistance = distance;
                }
            }
        }
        return closestPair;
    }

}