Collection.sort with multiple fields using Java 8

package com.java8.chapter1;

import java.util.Arrays;
import java.util.Comparator;
import java.util.List;
import static java.util.Comparator.*;



 public class Example1 {

    public static void main(String[] args) {
        List<Employee> empList = getEmpList();


        // Before Java 8 
        empList.sort(new Comparator<Employee>() {

            @Override
            public int compare(Employee o1, Employee o2) {
                int res = o1.getDesignation().compareTo(o2.getDesignation());
                if (res == 0) {
                    return o1.getSalary() > o2.getSalary() ? 1 : o1.getSalary() < o2.getSalary() ? -1 : 0;
                } else {
                    return res;
                }

            }
        });
        for (Employee emp : empList) {
            System.out.println(emp);
        }
        System.out.println("---------------------------------------------------------------------------");

        // In Java 8

        empList.sort(comparing(Employee::getDesignation).thenComparing(Employee::getSalary));
        empList.stream().forEach(System.out::println);

    }
    private static List<Employee> getEmpList() {
        return Arrays.asList(new Employee("Lakshman A", "Consultent", 450000),
                new Employee("Chaitra S", "Developer", 250000), new Employee("Manoj PVN", "Developer", 250000),
                new Employee("Ramesh R", "Developer", 280000), new Employee("Suresh S", "Developer", 270000),
                new Employee("Jaishree", "Opearations HR", 350000));
    }
}

class Employee {
    private String fullName;
    private String designation;
    private double salary;

    public Employee(String fullName, String designation, double salary) {
        super();
        this.fullName = fullName;
        this.designation = designation;
        this.salary = salary;
    }

    public String getFullName() {
        return fullName;
    }

    public String getDesignation() {
        return designation;
    }

    public double getSalary() {
        return salary;
    }

    @Override
    public String toString() {
        return "Employee [fullName=" + fullName + ", designation=" + designation + ", salary=" + salary + "]";
    }

}

Java8 program to read data from file and displaying Statistics of data

 
Employees date of birth is stored in an file in the following format:

08/06/1984

29/5/1982

20/1/1989

17/5/1989

22nd October 1991

14th December 1991

20th February 1994

27th July 1990

26th Dec 1991

12th Nov 1990

19th Dec 1990

27th Dec 1989

Java8 IntSummaryStatistics class to calculate total employees, total age, and average age group of the organization.  

 import java.nio.file.Files;  
 import java.nio.file.Paths;  
 import java.time.LocalDate;  
 import java.util.IntSummaryStatistics;  
 import java.util.stream.Stream;  
 public class DemoExample {  
      public static void main(String... args) {  
           try (Stream<String> lines = Files.lines(Paths.get("demo"))) {  
                IntSummaryStatistics intstream = lines.sequential()  
                          .mapToInt(e -> LocalDate.now().getYear() - Integer.parseInt(e.substring(e.trim().length() - 4)))  
                          .summaryStatistics();  
                long total_age = intstream.getSum();  
                long total_count = intstream.getCount();  
                double avg_age = intstream.getAverage();  
                System.out.println("Total employees :" + total_count);  
                System.out.println("Total age is :" + total_age);  
                System.out.println("Average age is :" + avg_age);  
           } catch (Exception e) {  
                e.printStackTrace();  
           }  
      }  
 }  

Java with Apache POI

Apache POI to create excel file

---

Maven dependencies:


<dependency>
<groupId>org.apache.poi</groupId>
<artifactId>poi-ooxml</artifactId>
<version>3.9</version>
</dependency>

<dependency>
<groupId>org.apache.poi</groupId>
<artifactId>poi</artifactId>
<version>3.9</version>
</dependency>

Example:

---

 import java.io.File;  
 import java.io.FileOutputStream;  
 import java.io.IOException;  
 import java.nio.file.Files;  
 import java.nio.file.Paths;  
 import org.apache.poi.ss.usermodel.Cell;  
 import org.apache.poi.ss.usermodel.Row;  
 import org.apache.poi.ss.usermodel.Sheet;  
 import org.apache.poi.ss.usermodel.Workbook;  
 import org.apache.poi.xssf.usermodel.XSSFWorkbook;  
 public class WorkingWithExcel {  
      public static void main(String[] args) {  
           createWorkBook();  
      }  
      /**  
       * Create workbook with one work sheet. Once work sheet is created, then  
       * content will be added to the work sheet.  
       */  
      private static void createWorkBook() {  
           final String WORKBOOK_NAME = "emp_workbook.xlsx";  
           if (!Files.exists(Paths.get(WORKBOOK_NAME))) {  
                try (FileOutputStream fos = new FileOutputStream(new File("emp_workbook.xlsx"))) {  
                     Workbook workbook = new XSSFWorkbook();  
                     Sheet sheet = workbook.createSheet("emp_details");  
                     int rowcount = 0;  
                     Row row = sheet.createRow(rowcount++);  
                     Object[] colHeading = getColumnHeadings();  
                     int i = 0;  
                     for (Object obj : colHeading) {  
                          Cell cell = row.createCell(i++);  
                          cell.setCellValue((String) obj);  
                     }  
                     Object empData[][] = getEmpData();  
                     for (Object obj[] : empData) {  
                          i = 0;  
                          row = sheet.createRow(rowcount++);  
                          for (Object ob : obj) {  
                               Cell cell = row.createCell(i++);  
                               cell.setCellValue((String) ob);  
                          }  
                     }  
                     workbook.write(fos);  
                     System.out.println("Work book is created successfully with name :" + WORKBOOK_NAME);  
                } catch (IOException e) {  
                     e.printStackTrace();  
                }  
           } else {  
                System.out.println("File already exists with the name :" + WORKBOOK_NAME);  
           }  
      }  
      /**  
       * To return work sheet headings  
       *   
       * @return  
       */  
      private static Object[] getColumnHeadings() {  
           return new Object[] { "EMPNO", "ENAME", "EMAIL", "CITY" };  
      }  
      /**  
       * Actual data to add to work sheet  
       *   
       * @return  
       */  
      public static Object[][] getEmpData() {  
           return new Object[][] { { "SPAN001", "Lakshman", "lakshman.a@spaneos.com", "Bangalore" },  
                     { "SPAN002", "Krish", "krish.t@spaneos.com", "Bangalore" },  
                     { "SPAN003", "Suresh", "suresh.s@spaneos.com", "Bangalore" },  
                     { "SPAN004", "Ramesh", "ramesh.r@spaneos.com", "Bangalore" } };  
      }  
 }  

Python Programs

Python Programs:

 #Program to print Fibonacci series upto "N". "N" is user input  
 N = int(input("Enter a valid integer : => "))  
 a, b = 0, 1  
 while b <= N:  
   print(b)  
   a, b = b, a + b;  

Selection, Bubble, Insertion Sort in Java

import java.util.Arrays;

public class SortingDemo {
    public static void main(String... args){
            int a[]={2,1,3,5,4,8,7,9,6};
            System.out.println("Before Sorting :"+ Arrays.toString(a));
            insertionSort(a);
            System.out.println("After Sorting :"+ Arrays.toString(a));
    }
    public static void selectionSort(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;
                        }

                    }
            }
    }
    public static void bubbleSort(int... a){
            for(int i=0;i<a.length;i++){
                for(int j=0;j<a.length-i-1;j++){
                    if(a[j]>a[j+1]){
                        int temp=a[j];
                        a[j]=a[j+1];
                        a[j+1]=temp;
                    }
                }
            }
    }
    public static void insertionSort(int... arr){
            for(int i=1;i<arr.length;i++){
                int j=i-1;
                int temp=arr[i];
                while(j>=0 && temp<arr[j]){
                    arr[j+1]=arr[j];
                    j--;
                }
                arr[j+1]=temp;
            }
    }
}

Selection Sort

 #include<stdio.h>  
 #include<conio.h>  
 void showElements(int arr[],int n){  
      int i;  
      if(n==0)  
           printf("[]");  
      else if(n>0)  
           printf("[");  
      for(i=0;i<n;i++){  
           if(i==n-1){  
                printf("%d",arr[i]);  
                printf("]");  
           }else  
                printf("%d,",arr[i]);  
      }  
 }  
 void sortData(int arr[],int n){  
      int i,j,temp;  
      for(i=0;i<n-1;i++){  
           for(j=i+1;j<n;j++){  
                if(arr[i]>arr[j]){  
                  temp=arr[i];  
                  arr[i]=arr[j];  
                  arr[j]=temp;  
                }  
           }  
      }  
 }  
 int getLength(int arr[]){  
      int i=0;  
      while(arr[i]!='\0'){  
        i++;  
      }  
      return i;  
 }  
 void main(){  
      int arr[]={2,1,3,4,9,8,7,6,5};  
      int i,j,len;  
      clrscr();  
      len=getLength(arr);  
      printf("\n Before Sorting Array Elements \n");  
      showElements(arr,len);  
      sortData(arr,len);  
      printf("\n After Sorting Array Elements \n");  
      showElements(arr,len);  
      getch();  
 }  

Floating point error in c - struct

 //Link float error solution  
 #include<stdio.h>  
 #include<conio.h>  
 struct Employee{  
      int empno;  
      char name[50];  
      float salary;  
 };  
 void floatError(float *a){  
      float b=*a;  
      floatError(&b);  
 }  
 void showDetails(struct Employee *emp){  
      printf("\n %d  %s %f",emp->empno,emp->name,emp->salary);  
 }  
 void main(){  
      struct Employee e1;  
      struct Employee e2;  
      clrscr();  
      e1.empno=1001;  
      strcpy(e1.name,"Krishna G");  
      e1.salary=29999.879;  
      e2.empno=1002;  
      strcpy(e2.name,"Nanda Gopal Krishna");  
      e2.salary=59999.987;  
      showDetails(&e1);  
      showDetails(&e2);  
      getch();  
 }  

Stack in C - using array implementation

 //Stack implementation using arrays  
 #include<stdio.h>  
 #include<conio.h>  
 int max=10;  
 int stack[10];  
 int top=-1;  
 int i;  
 void push(int ele){  
   if(top<max){  
      stack[++top]=ele;  
      printf("\n The element is added to stack %d",ele);  
   }else{  
      printf("\n Stack is overflow");  
   }  
 }  
 void pop(){  
      if(top==-1){  
           printf("\n Stack is underflow");  
      }else{  
           printf("\n Element %d is removed ",stack[top]);  
           top--;  
      }  
 }  
 void display(){  
     if(top==-1){  
           printf("\n Stack is empty");  
     }else{  
       printf("[");  
       for(i=0;i<=top;i++){  
           printf(" %d ",stack[i]);  
           if(i<top)  
           printf(",");  
       }  
       printf("]");  
     }  
 }  
 void main(){  
    int ch,ele;  
    int choice=1;  
    clrscr();  
    while(choice){  
       printf("\n1.PUSH 2.POP 3.DISPLAY\n ");  
       scanf("%d",&ch);  
       switch(ch){  
           case 1:printf("\n Enter the element to push \n");  
               scanf("%d",&ele);  
               push(ele);  
               break;  
           case 2:pop();  
               break;  
           case 3:display();  
               break;  
           default: printf("\n Enter valid number (1 to 3)\n");  
       }  
       printf("\n Do you want to continue (yes = 1 no = 0) \n");  
       scanf("%d",&choice);  
    }  
 }  

Reverse String Word by Word in Java ( Character array)

public class ReverseWords {
    public static void main(String[] args) {
        

        String data = "Me loves India";
        System.out.println(data);
        char arr[] = data.toCharArray();
       

        int l = 0;
        for (int i = arr.length - 1; i >= 0; i--) {
            l++;
            

             if (arr[i] == ' ' || i == 0) {
                if (i == 0) {
                    for (int j = i; j < i + l; j++)
                        System.out.print(arr[j]);
                } else {
                    for (int j = i + 1; j < i + l; j++)
                        System.out.print(arr[j]);
                    System.out.print(" ");
                }
                l = 0;
               }
        }

    }
}

Reverse of the given number using recursion in Java

public int reverse(int num) {
    if (num < 10) {
         return num;
    } else {

          int rev=num%10 * (int) Math.pow(10, (int) Math.log10(num));
          return  rev+ reverse(num / 10);

    }
}

      ------ OR --------

public int reverse(int num) {

   retrun (num < 10)? num:num%10 * (int) Math.pow(10, (int) Math.log10(num))

           +reverse(num / 10);

   }
}

Reponse.Redirect with form data in java

//Sending Data Using Get Method

<script type="text/javascript">
 function sendResponseGet(url, extradata, success) {
  var form = $('<form action="' + url + '" method="get">'
    + '<input type="text" name="message" value="' + extradata + '" />'
    + '<input type="text" name="transid" value="' + success + '" />'
    + '</form>');
  form.submit();
 }

// Sending Data Using Post Method

 function sendResponsePost(url, extradata, success) {
  var form = $('<form action="' + url + '" method="post">'
    + '<input type="text" name="message" value="' + extradata + '" />'
    + '<input type="text" name="transid" value="' + success + '" />'
    + '</form>');
  form.submit();
 }
</script>

JSP Code


<button class="btn btn-primary custom-btn"
                    onclick='sendResponseGet("<%=uri%>","
                   <%=message%>","success")'>Send Oxigen Response GET</button>
<hr>
<button class="btn btn-primary custom-btn"
                   onclick='sendResponsePost("<%=uri%>",
                   "<%=message%>","success")'>Send Oxigen Response POST</button>