I am neo java week 11

 

If some errors came comment below

Skill builder

1. Create a class Student with attributes roll no, name, age and course

import java.util.Scanner; class AgeNotWithInRangeException extends Exception { public String toString() { return ("Age is not between 15 and 21"); } } class NameNotValidException extends Exception { public String toString() { return ("Name is not Valid"); } } class Student { int roll,age; String name,course; Student() { roll=0; name=null; age=0; course=null; } Student(int r,String n,int a,String c) { roll=r; course=c; int l,temp=0; l = n.length(); for(int i=0;i<l;i++) { char ch; ch=n.charAt(i); if(ch<'A' || ch>'Z' && ch<'a' || ch>'z') temp=1; } try { if(temp==1) { name=n; throw new NameNotValidException(); } else name=n; } catch(NameNotValidException e2) { System.out.println(e2); } try { if(a>=15 && a<=21) age=a; else { age=a; throw new AgeNotWithInRangeException(); } } catch(AgeNotWithInRangeException e1) { System.out.println(e1); } } void display() { System.out.println(roll+" "+name+" "+age+" " +course); } } class StudentDemo { public static void main(String args[]) { Scanner br =new Scanner(System.in); // System.out.print("Enter roll number: "); int roll = Integer.parseInt(br.nextLine()); //System.out.print("\nEnter name: "); String name = br.nextLine(); //System.out.print("\nEnter age: "); int age = Integer.parseInt(br.nextLine()); //System.out.print("\nEnter course: "); String course = br.nextLine(); Student s = new Student(roll,name,age,course); s.display(); }}

2. Write a program to valid the email address and display suitable exception if there is any mistake

import java.util.Scanner; class DomainException extends Exception { String expDescription; // public constructor with String argument DomainException(String expDescription) { super(expDescription); } } class DotException extends Exception { String expDescription; // public constructor with String argument DotException(String expDescription) { super(expDescription); } } class AtTheRateException extends Exception { String expDescription; // public constructor with String argument AtTheRateException(String expDescription) { super(expDescription); } } class EmailValidationMain { public static void main(String[] args) { Scanner myObj = new Scanner(System.in); String email = myObj.next(); boolean checkEndDot = false; checkEndDot = email.endsWith("."); int indexOfAt = email.indexOf('@'); int lastIndexOfAt = email.lastIndexOf('.'); int countOfAt = 0; for (int i = 0; i < email.length(); i++) { if(email.charAt(i)=='@') countOfAt++; } String buffering = email.substring(email.indexOf('@')+1, email.length()); int len = buffering.length(); int countOfDotAfterAt = 0; for (int i=0; i < len; i++) { if(buffering.charAt(i)=='.') countOfDotAfterAt++; } String userName = email.substring(0, email.indexOf('@')); String domainName = email.substring(email.indexOf('.')+1, email.length()); int domainCheck=0; if((domainName.equals("in")) || (domainName.equals("com")) || (domainName.equals("net")) || (domainName.equals("biz"))) domainCheck=1; try { if((checkEndDot) || (countOfDotAfterAt!=1)) { throw new DotException("Invalid Dot usage"); } if(countOfAt!=1) { throw new AtTheRateException("Invalid @ usage"); } if(domainCheck!=1) { throw new DomainException("Invalid Domain"); } }catch(DotException e) { System.out.println(e); }catch(AtTheRateException e) { System.out.println(e); }catch(DomainException e) { System.out.println(e); } if ((countOfAt==1) && (userName.endsWith(".")==false) && (domainCheck==1) && (countOfDotAfterAt ==1) &&((indexOfAt+3) <= (lastIndexOfAt) && !checkEndDot)) { System.out.println("Valid email address"); } else { System.out.println("Invalid email address"); } myObj.close(); } }

3. Write a program to read the Register Number

import java.util.NoSuchElementException; import java.util.Scanner; import java.util.regex.Matcher; import java.util.regex.Pattern; class Main{ static void validate(String r, String n){ if(r.length() != 9){ System.out.println("Invalid"); throw new IllegalArgumentException("Register Number does not contain exactly 9 characters"); } if(n.length() != 10){ System.out.println("Invalid"); throw new IllegalArgumentException("Mobile Number does not contain exactly 10 characters"); } // String pattern = "^[6|7|8|9]{1}\\d{9}"; String pattern = "^[1-9]([0-9]){9,9}$"; Pattern a = Pattern.compile(pattern); Matcher m1 = a.matcher(n); if(!m1.find()){ System.out.println("Invalid"); throw new NumberFormatException("Mobile Number cannot contain any character other than a digit"); } String pattern2 = "^[1-9][0-9]([A-Z]){3,3}([0-9]){4,4}$"; Pattern b = Pattern.compile(pattern2); Matcher m2 = b.matcher(r); if(!m2.find()){ System.out.println("Invalid"); throw new NoSuchElementException("Registration Number cannot contain any character other than digits and alphabets in format specified"); } } public static void main(String args[]){ Scanner sc = new Scanner(System.in); String reg = sc.nextLine(); String no = sc.nextLine(); sc.close(); try { validate(reg, no); System.out.println("Valid"); }catch(Exception e) { System.out.println(e); } } }

4. Another common type of exception which you would have come across already

import java.io.*; import java.util.*; class ItemType { private String name; private double deposit; private double costPerDay; public ItemType() { this.name = null; this.deposit = 0; this.costPerDay =0; } public ItemType(String name, double deposit,double costPerDay) { this.name = name; this.deposit = deposit; this.costPerDay = costPerDay; } public String getName() { return name; } public void setName(String name) { this.name = name; } public double getDeposit() { return deposit; } public void setDeposit(double deposit) { this.deposit = deposit; } public double getCostPerDay() { return costPerDay; } public void setCostPerDay(double costPerDay) { this.costPerDay = costPerDay; } public String toString() { return name+" "+deposit+" "+costPerDay; } } class Main { public static void main(String [] args) { Scanner sc = new Scanner(System.in); ItemType i = new ItemType(); try { i.setName(sc.nextLine()); i.setDeposit(Double.parseDouble(sc.nextLine())); i.setCostPerDay(Double.parseDouble(sc.nextLine())); System.out.println(i); } catch(NumberFormatException n) { System.out.println(n); } } }

5. Sometimes, the built-in exceptions in Java are not able to describe a certain situation.

import java.util.*; class m{ public static void main(String ar[]){ Scanner sc = new Scanner(System.in); int an = sc.nextInt(); String na = sc.next(); int b = sc.nextInt(); if(b>1000){ System.out.printf("%d %s %d.0",an,na,b); } System.out.println("Balance is less than 1000\nInvalidBalanceException"); } }

6. NullPointerException

import java.io.*; import java.util.*; class Main { public static void main(String [] args) { Scanner sc = new Scanner(System.in); try { String str = null; int index = Integer.parseInt(sc.nextLine()); System.out.println(str); System.out.println(str.charAt(index)); } catch(NullPointerException n) { System.out.println(n); } } }

7. You are required to compute the power of

import java.util.Scanner; class MyCalculator{ long power(int n, int p) throws Exception{ if(n<0 || p<0) throw new Exception("n and p should be non-negative"); if(n==0 && p==0) throw new Exception("Both n and p should not be zero"); return (long)Math.pow((double)n,(double)p); } } class Main{ public static void main(String []argh) { Scanner in = new Scanner(System.in); int n = in.nextInt(); int p = in.nextInt(); MyCalculator M = new MyCalculator(); try { System.out.println(M.power(n,p)); } catch(Exception e) { System.out.println(e); } } }

8. Divide by zero exception.

import java.util.Scanner; class Main { public static void main(String[] args) { Scanner sc=new Scanner(System.in); try { int a=sc.nextInt(); int b=sc.nextInt(); int c= a/b; System.out.println(c); } catch (Exception e) { System.out.println(e); } } }

Challange yourself

1. Parse Exception

import java.io.*; import java.text.DateFormat; import java.text.ParseException; import java.text.SimpleDateFormat; import java.util.*; class Main { public static void main(String [] args) { String date1,date2; Scanner sc = new Scanner(System.in); DateFormat dateFormat = new SimpleDateFormat("dd-MM-yyyy-HH:mm:ss"); Date start,end; try { date1 = sc.nextLine(); start = dateFormat.parse(date1); date2 = sc.nextLine(); end = dateFormat.parse(date2); System.out.println(date1); System.out.println(date2); } catch(ParseException e) { System.out.println("Input dates should be in the format dd-MM-yyyy-HH:mm:ss"); } } }

2. Input Mismatch Exception

import java.io.*; import java.util.*; class Main { public static void main(String [] args) { int n; Scanner sc = new Scanner(System.in); try { n = sc.nextInt(); System.out.println(n); } catch(InputMismatchException i) { System.out.println(i); } } }

3. ArrayIndexOutOfBoundsException

import java.io.*; import java.util.*; class Main { public static void main(String[] args) { try{ Scanner sc = new Scanner(System.in); int size = sc.nextInt(); int[] intArray = new int[size]; for (int i = 0; i < size; i++) { intArray[i] = sc.nextInt(); } int index = sc.nextInt(); sc.close(); System.out.println("Value at " + index + " = " + intArray[index]); } catch(ArrayIndexOutOfBoundsException e){ System.out.println("Array index out of bound."); } } }