Bubble sort algorithm using array in Java.

For theoretical reference you can see wiki link.

http://en.wikipedia.org/wiki/Bubble_sort

For programmatic reference you can check this.


public class BubbleSort {

    public static void main(String[] args) {
       
        int arr[] = { 2, 7, 4, 1, 5, 3};
        showAll(bubbleSort(arr));
    }
   
    private static int [] bubbleSort(int arr[]){
        while(true){
            int count = 0;
            for (int i = 0; i < arr.length - 1; i++) {
                if(arr[i] > arr[i+1]){
                    int temp = arr[i];
                    arr[i] = arr[i + 1];
                    arr[i + 1] = temp;
                    count ++;
                }
            }
            if(count == 0)
                break;
        }
        return arr;
    }
   
    private static void showAll(int[] arr){
        for (int i : arr) {
            System.out.println("" + i);
        }
    }

}

Selection Sort in Java

For theoretical reference you can see wiki link.
http://en.wikipedia.org/wiki/Selection_sort

For programmatic reference you can check this.

public class SelectionSort {
   
    public static void main(String[] args) {
        int [] arr = {3, 4, 2, 1, 5, 10, 99, 12, 1, 7};
        showAll(descSort(arr));
    }

    private static int [] descSort(int[] arr){
        for(int i = 0; i <= arr.length -1; i++){
            for(int j = i+1; j < (arr.length); j++){
                if(arr[i] > arr[j]){
                    int temp = arr[i];
                    arr[i] = arr[j];
                    arr[j] = temp;
                }
            }
        }
        return arr;
    }
   
    private static void showAll(int[] arr){
        for (int i : arr) {
            System.out.println("" + i);
        }
    }
}

Android Webview tricks to get alert and console.log() messages.

There are many tutorials to write a webview so i am not covering the ways to create a webview instead  i wanted to show how we can get the javascript consol.log('test'), and alert('message') from WebChromeClient api  which can be used to debug hybrid application.




private class SampleWebChromeClient extends WebChromeClient {

@Override
public boolean onConsoleMessage(ConsoleMessage consoleMessage) {
   Log.d("SampleActivity", consoleMessage.message() + " -- From line "
            + consoleMessage.lineNumber() + " of "
            + consoleMessage.sourceId() );

   return true;
}

@Override
public boolean onJsAlert(WebView view, String url, String message,
JsResult result) {
  Log.d("SampleActivity", message);
        //new AlertDialog.Builder(view.getContext()).setMessage(message).setCancelable(true).show();
  Toast.makeText(getApplicationContext(), message, Toast.LENGTH_SHORT).show();
        result.confirm();
        return true;
}

}


For KitKat > using the below code and you can debug inside the web view. For more details refer here.

  if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.KITKAT) {
      WebView.setWebContentsDebuggingEnabled(true);
  }

Data Structure - Queue(JAVA) using array

For theoretical reference you check wiki.

http://en.wikipedia.org/wiki/Queue_%28data_structure%29

Java you can refer the code.

import java.io.BufferedReader;
import java.io.IOException;
import java.io.InputStreamReader;

public class QueueKrk {

 private static final int MAX = 3;
 private static int[] QUEUE = new int[MAX];
 private static int top = -1;
 private static int rear = 0;

 private enum Function {
  PUSH, POP, PRINTALL
 };

 private static void push() {
  if (top < MAX -1) {
   System.out.println("Enter the value to added to the queue");
   int value = readValue();
   QUEUE[++top] = value;
  } else {
   System.out.println("The queue has reached the maximum value");
  }
 }

 private static void peek() {
  if(top >= rear){
   rear++;
  }else{
   System.out.println("Nothing to Peek");
  }

 }

 private static void printAll() {
  if (top >= rear) {
   int i = 0;
   for (i = rear; i <= top; i++) {
    System.out.println(QUEUE[i]);
   }
  } else {
   System.out.println("The queue is empty");
  }
 }

 private static int readValue() {
  int input = 0;
  try {
   BufferedReader br = new BufferedReader(new InputStreamReader(
     System.in));
   input = Integer.parseInt(br.readLine());
  } catch (NumberFormatException nfe) {
   System.err.println("Invalid Format!");
   System.exit(0);
  } catch (IOException e) {
   e.printStackTrace();
  }
  return input;
 }

 public static void main(String[] args) {
  init();
 }

 private static void init() {
  System.out.println("For Push enter 0, Peek enter 1 and 2 to print all. For exit enter non number");
  int selection = readValue();
  optionSelection(selection);
 }

 private static void optionSelection(int selection) {
  Function function = null;
  try {
   function = Function.values()[selection];
  } catch (ArrayIndexOutOfBoundsException ex) {
   System.out.println("Enter either '0' or '1' or '2' for push, Peek , view all respectively");
   init();
  }
  switch (function) {
  case PUSH:
   push();
   init();
   break;
  case POP:
   peek();
   init();
   break;
  case PRINTALL:
   printAll();
   init();
   break;
  default:
   break;
  }
 }

}

Data Structure - Stack (JAVA) using array

For theoretical reference you can see wiki link. 
http://en.wikipedia.org/wiki/Stack_%28data_structure%29


Java Stack using array .

import java.io.BufferedReader;
import java.io.IOException;
import java.io.InputStreamReader;

public class StackKrk {

 private static final int MAX = 3;// constant for the size of the stack.
 private static final int[] STACK = new int[MAX]; 
 private static int TOP = 0; // Flag for the stack position.
 private  enum Function{PUSH, POP, PRINTALL};
 
 public static void main(String[] args) {
  init();
 }
 
 private static void init(){
  System.out.println("For Push enter 0, Pop enter 1 and 2 to print all. For exit enter non number");
  int selection = readValue();
  
  optionSelection(selection);
 }
 
 private static void optionSelection(int selection){
  Function function = null;
  try{
   function = Function.values()[selection];
  }catch(ArrayIndexOutOfBoundsException ex){
   System.out.println("Enter either '0' or '1' or '2' for push, pop , view all respectively");
   init();
  }
  switch (function) {
  case PUSH:
   push();
   init();
   break;
  case POP:
   pop();
   init();
   break;
  case PRINTALL:
   printAll();
   init();
   break;
  default:
   
   break;
  }
 }

 private static int readValue() {
  int input = 0;
  try {
   BufferedReader br = new BufferedReader(new InputStreamReader(System.in));
   input = Integer.parseInt(br.readLine());
  } catch (NumberFormatException nfe) {
   System.err.println("Invalid Format!");
   System.exit(0);
  } catch (IOException e) {
   e.printStackTrace();
  }
  return input;
 }

 private static void push() {
  if (TOP == MAX) {
   System.out.println("Reached the maximum stack value");
  } else {
   System.out.println("Enter the value to be pushed ::>");
   int value = readValue();
   STACK[TOP++] = value;
  }
 }
 
 private static void pop() {
  if (TOP == 0) {
   System.out.println("The stack is empty");
  } else {
   System.out.println("The poped element of the stack ::>" + STACK[--TOP]);
   STACK[TOP] = 0;
  }
 }
 private static void printAll(){
  for(int i=0; i<=TOP-1; i++){
   System.out.println("Value in the stack position["+i+"]  "+STACK[i]);
  }
    
 }


}

Using GSON Effectively

Program of Deserialize/Serialize JSON.I am writing it below. First download the Gson then add it to the eclipse project.

Step 1: Create a Dog class with getters and setters as below.

package myobject;



public class Dog {



 String name;





 int age








 public String getName() {





  return name;





 }





 public void setName(String name) {





  this.name = name;





 }





 public int getAge() {





  return age;





 }





 public void setAge(int age) {





  this.age = age;





 }





}

Step 2: Write a common GsonSerializer as below with generics so any class type can be passed.

package common;





import com.google.gson.Gson;





import com.google.gson.GsonBuilder;


//Generics is used so any class type can be passed



public class GsonSerializer<T> {





 public T Deserialize(String json, Class classOfT) {





  Gson gn = new GsonBuilder().create();





  return (T) gn.fromJson(json, classOfT);





 }





 public String Serialize(T object) {





  Gson gn = new GsonBuilder().create();





  return gn.toJson(object);





 }





}

 3: Write a main method for calling the example

package gsoncaller;



import myobject.Dog;



import common.GsonSerializer;




public class MyGsonCaller {



 public static void main(String[] args) {



  Dog dog = new Dog();



  dog.setAge(1);



  dog.setName("mela");



  GsonSerializer<Dog> serializer = new GsonSerializer<Dog>();



  serializer.Serialize(dog);



  System.out.println("My json string ::>" + serializer.Serialize(dog));



  dog = serializer.Deserialize(serializer.Serialize(dog), Dog.class);



  String name = dog.getName();



  int age = dog.getAge();



  System.out.println("Name ::>" + name);



  System.out.println("Age ::>" + age);



 }



}

The out put is:

My json string ::>{"name":"mela","age":1}

Name ::>mela

Age ::>1

Eclipse short cut keys

Highlighted the most useful shortcut keys. 1. Navigation
Shortcut	Description
CTRL + SHIFT + R	Open / Search for resources, e.g. files
CTRL + SHIFT + T	Open / Search for Types
CTRL + E	Allows to select an editor from the currenlty open editors
CTRL + F8	Shortcut for switching perspectives
ALT + LEFT ARROW KEY or ALT + RIGHT ARROW KEY	Go to prev/ next editor position in history
Ctrl-PageUp/PageDown	Previous/next tab
F3	Go to declaration of this variable
CTRL + SHIFT + P	Go to matching bracket
CTRL + Q	Go to editor area and position the cursor at the last changed position
2. Search
Shortcut	Description
Ctrl + .	Go to next problem
Ctrl + ,	Go to previous problem
F3 on a variable	Goto Declaration of this variable
F4 on a variable	Show type hierarchy
CTRL + J , CTRL +k	Incremental search, find next
CTRL+ SHIFT +k	Decremental search,find previous
CTRL + SHIFT + G	Search for reference in the workspace
3. Run
Shortcut	Description
Ctrl F11	Run last launched
Alt + Shift + X - J	Run as Java application
4. Editing
Shortcut	Description
CTRL + 1	Quickfix, dependend on cursor position. See Quickfix for details.
CTRL + Space	Content assist/ code completion, see Content Assist for details.
CTRL + T	Show inline inline inheritance tree of the current Java class
CTRL + O	Show inline all methods of the current class, press CTRL+O again to show the inherited methods
F12	Focuses the editor (especially helpful if you working with Fast Views
Ctrl + M	Maximize Java editor
CTRL + Shift + F	Format source code
CTRL + Shift + O	Organize the imports / Will import the missing imports.
CTRL + Q	Last edited position
5. Arrow Keys
Shortcut	Description
CTRL + Left	Move one element to the left
CTRL + Right	Move one element to the right
CTRL + ALT + Up/Down	Copy line
ALT + Up / Down	Move line up / down
ALT + SHIFT Up / Down	Select the previous / next syntactical element
ALT + SHIFT Up / Down / Left / Right	Extending / Reducing the selection of the previous / next syntactical element
CTRL + Up / Down	Scroll up / down a line in the editor
6. Delete
Shortcut	Description
Ctrl + D	Deletes line
CTRL + SHIFT + DELETE	Delete until end of line
CTRL + DELETE	Delete next element
CTRL + BACKSPACE	Delete previous element
7. Variable assignment
Shortcut	Description
Ctrl + 2 + L	Assign statement to new local variable
Ctrl + 2 + F	Assign statement to new field
8. Programming
Coding
Shortcut	Description
Shift + F2	Call the Javadoc for the selected type / class / method
Alt+Shift + N + Letter	Type shortcut for the command, e.g. njc to create a new Java class or npip to create a new Plugin project.
Alt + Shift + Z	Surround block with try and catch
9. Refactoring
Shortcut	Description
ALT- SHIFT +R	Rename
CTRL+2,R	Rename locally (in file), faster then ALT- SHIFT +R
ALT- SHIFT + T	Opens the quick refactoring menu
10. Debugging
Shortcut	Description
F11	Debug last run
Ctrl + Shift + B	Toggle breakpoint
F5	Single Step (Down)
F6	Single Step (Jump)
F7	Up