JavaKing

class ConsInfo {
public static void main(String[] args) {
if (args.length == 0) {
System.out.println("PLEASE PASS THE CLASS NAME..!");
} else {
try {
Class c = Class.forName(args[0]);
printConsts(c);
} catch (ClassNotFoundException cnfe) {
System.out.println(args[0] + " DOES NOT EXISTS");
}
}
}
static void printConsts(Class c) {
java.lang.reflect.Constructor Cons[] = c.getConstructors();
System.out.println("NUMBER OF CONSTRUCTORS:" + Cons.length);
System.out.println("NAME OF THE CONSTRUCTOR:"+c.getName());
for (int i = 0; i < Cons.length; i++) {
System.out.print(c.getName() + "(");
Class cp[] = Cons[i].getParameterTypes();
for (int j = 0; j < cp.length; j++) {
System.out.print(cp[j].getName() + ")");
}
System.out.println("\b" + ")");
}
}
}

A name in the program is an identifier it may be class name or method name, variable name or label name.

Rules for defining Identifiers

1) A java identifier is a sequence of characters, where each character may be a letter from a-z or A-Z or a digit form 0-9 or currency symbol $ or connecting punctuation – , if we are using any other symbol we will get Compile time error “IllegalCharacter”.

2) Identifier should not be starts with digit.

3) There is no length limit for java identifiers but it is not recommended to take more than 15
length.

4) Java Identifiers are case sensitive

Example:

class FundaDemo
{
public static void main(String[] args)
{
int String = 10;
System.out.println(String);
}
}

Output- 10

Exercise- Which of the following are valid Identifiers

1) total#
2) all@hands
3) 123total
4) break
5) String
6) total_number
7) $_$
8) $ca$h

Ans- 5,6,7,8

import java.util.Scanner;
public class Series
{
public static void main(String[] args)
{
Scanner sc = new Scanner(System.in);
System.out.println("Enter the no of terms ");
int n = sc.nextInt();
double sum = 0;
for (int i = 1; i <= n; i++)
sum = sum + (double) 1 / Math.pow(i, 2);
System.out.println("Sum of series = " + sum);
}
}

Output:
Enter the no of terms
5
Sum of series = 1.4636111111111112
BUILD SUCCESSFUL (total time: 2 seconds)

import java.util.Scanner;
public class Series
{
public static void main(String[] args)
{
Scanner sc = new Scanner(System.in);
System.out.println("Enter the no of terms ");
int n = sc.nextInt();
int sum = 0, i = 0;
for (int j = 1; j <= n; j++)
{
for (i = 1; i <= j; i++)
{
sum = sum + i;
}
i = 1;
}
System.out.println("Sum of series = " + sum);
}
}

Output:
Enter the no of terms
4
Sum of series = 20
BUILD SUCCESSFUL (total time: 2 seconds)

import java.util.Scanner;
public class Series
{
public static void main(String[] args)
{
Scanner sc = new Scanner(System.in);
double sum = 0;
System.out.println("Enter the no of terms ");
int n = sc.nextInt();
for (int i = 1; i <= n; i++)
{
if (i % 2 == 0) {
sum = sum - (double) 1 / (i * i * i);
} else {
sum = sum + (double) 1 / (i * i * i);
}
}
System.out.println(" Sum of the series : " + sum);
}
}

Output:

Enter the no of terms
5
Sum of the series : 0.904412037037037
BUILD SUCCESSFUL (total time: 3 seconds)

import java.util.Scanner;
public class Series
{
public static void main(String args[])
{
Scanner sc = new Scanner(System.in);
System.out.print("Enter the number of terms: ");
int n = sc.nextInt();
int s = 0, c; // s for terms of series, c for n terms
for (c = 1; c <= n; c++) // To generate n terms
{
s = s * 10 + 1;
System.out.print(s + " ");
} //for ends
}
}

Output:
Enter the number of terms: 7
1, 11, 111, 1111, 11111, 111111, 1111111......
BUILD SUCCESSFUL (total time: 3 seconds)

import java.util.Scanner;
public class Series
{
public static void main(String args[])
{
Scanner sc = new Scanner(System.in);
System.out.print("Enter the number of terms: ");
int n = sc.nextInt();
int s = 0, c; // s for terms of series, c for counter to generate n terms
for (c = 1; c <= n; c++) {
s = s * 10 + c;
System.out.print(s + " ");
}
}
}

Output:
Enter the number of terms: 6
1, 12, 123, 1234, 12345, 123456.......
BUILD SUCCESSFUL (total time: 3 seconds)

import java.util.Scanner;
public class OddSeries
{
public static void main(String args[])
{
Scanner sc = new Scanner(System.in);
System.out.print("Enter the number of terms: ");
int n = sc.nextInt();
int i = 1, c, f = 1; // i for odd nos, c for counter, f for flag
for (c = 1; c <= n; c++) {
if (f % 2 == 0) {
System.out.print(-i + " ");
} else {
System.out.print(i + " ");
}
i += 2;
f++;
} //Loop ends
}
}

Output:

Enter the number of terms: 6
1 -3 5 -7 9 -11......
BUILD SUCCESSFUL (total time: 6 seconds)

import java.util.Scanner;
public class Series
{
public static void main(String args[]) {
Scanner sc = new Scanner(System.in);
int c, i = 2, n; // c for counter, i for even nos.
System.out.print("Enter the number of terms: ");
n = sc.nextInt();
System.out.print("\n");
for (c = 1; c <= n; c++, i += 2) //to generate n terms of the series
{
if (i % 4 == 0) {
System.out.print(-i + " ");
} else {
System.out.print(i + " ");
}
}
}
}

Output:

Enter the number of terms: 10
2 -4 6 -8 10 -12 14 -16 18 -20
BUILD SUCCESSFUL (total time: 6 seconds)

A tribonacci series is one in which the sum next term is the sum of previous three terms
Example 0 1 2 3 6 11 20………….

import java.util.Scanner;

public class Tribonacci

{

public static void main(String args[]) {

func(10);

}

static void func(int n) {

int a = 0, b = 1, c = 2, d = 0, i;

System.out.print(a + " , " + b + " , " + c);

for (i = 4; i <= n; i++) {

d = a + b + c;

System.out.print(", " + d);

a = b;

b = c;

c = d;

}

Output:

0 , 1 , 2, 3, 6, 11, 20, 37, 68, 125

BUILD SUCCESSFUL (total time: 1 second)

A fibonacci series is one in which the next term is the sum of previous two terms
Example. 0 1 1 2 3 5 8……

import java.util.Scanner;
public class Fibonacci
{
public static void main(String args[]) {
func(10);
}
static void func(int n) {
int a = 0, b = 1, c = 0, i;
System.out.print(a + " , " + b);
for (i = 3; i <= n; i++) {
c = a + b;
System.out.print(", " + c);
a = b;
b = c;
}
}
}

Output:

0 , 1, 1, 2, 3, 5, 8, 13, 21, 34
BUILD SUCCESSFUL (total time: 0 seconds)

import java.util.Scanner;
public class WordFrequencyCounter {
public static void main(String args[]) {
Scanner scan = new Scanner(System.in);
System.out.println("enter main string");
String s = scan.nextLine();
System.out.println("enter string to be searched");
String f = scan.nextLine();
s = s + " ";
int l = s.length();
char a;
int c = 0;
String s1 = "";
for (int i = 0; i < l; i++) {
a = s.charAt(i);
if (a != ' ') {
s1 = s1 + a;
} else {
if (s1.equalsIgnoreCase(f) == true) {
c++;
}
s1 = "";
}
}
System.out.println("Frequency of the word " + f + " is " + c);
}
}

Output:
Enter main string
Umesh Kumar Kushwaha Kumar
enter string to be searched
Kumar
Frequency of the word Kumar is 2

import java.io.BufferedReader;
import java.io.IOException;
import java.io.InputStreamReader;
public class RemoveVowels
{
public static void main(String args[]) throws IOException {
BufferedReader br = new BufferedReader(new InputStreamReader(System.in));
String str1, str2 = "";
char ch, ch1;
int i, len;
System.out.println("Enter the Sentence:");
str1 = br.readLine();
len = str1.length();
for (i = 0; i < len; i++) {
ch = str1.charAt(i);
ch1 = Character.toLowerCase(ch);
switch (ch1) {
case 'a':
case 'e':
case 'i':
case 'o':
case 'u':
break;
default:
str2 = str2 + ch;
} //switch ends
} //for ends
System.out.println("Modified string without vowels:" + str2);
} //method ends
}

Output:
Enter the Sentence:
umesh kumar kushwaha
Modified string without vowels:msh kmr kshwh

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

public class RemoveCommonDuplicateChar
{
public static void main(String args[]) throws IOException {
BufferedReader br = new BufferedReader(new InputStreamReader(System.in));
String s1, s2, s3 = "", s4 = "";
int a[], b[], x = 0, y = 0;
int len1, len2;
char ch;
int i, j;
System.out.println("Enter the first sentence:");
s1 = br.readLine().trim();
System.out.println("Enter the second sentence:");
s2 = br.readLine().trim();
len1 = s1.length();
len2 = s2.length();
a = new int[len1];
b = new int[len2];
for (i = 0; i < len1; i++) {
ch = s1.charAt(i);
for (j = 0; j < len2; j++) {
if (ch == s2.charAt(j)) {
break;
}
}
if (j != len2) {
a[x++] = i;
b[y++] = j;
}
}
for (i = 0; i < len1; i++) {
for (j = 0; j < x; j++) {
if (i == a[j]) {
break;
}
}
if (j == x) {
s3 = s3 + s1.charAt(i);
}
}
for (i = 0; i < len2; i++) {
for (j = 0; j < y; j++) {
if (i == b[j]) {
break;
}
}
if (j == y) {
s4 = s4 + s2.charAt(i);
}
}
System.out.println("Original string1=" + s1 + " Modified string1=" + s3);
System.out.println("Original string2=" + s2 + " Modified string2=" + s4);
}
}

Output:

Enter the first sentence:
Umesh Kumar Kushwaha
Enter the second sentence:
Rahul Kumar Singh
Original string1=Umesh Kumar Kushwaha Modified string1=Uessw
Original string2=Rahul Kumar Singh Modified string2=Rlua Singh

import java.io.BufferedReader;
public class ReverseOfString {
public static String reverseString(String s)
{
int l = s.length();
String backward = "";
for (int i = l - 1; i >= 0; i--)
{
backward = backward + s.charAt(i);
}
return backward;
}
public static void main(String args[]) {
String backwards = reverseString("Umesh Kushwaha");
System.out.println("Reverse String is " + backwards);
}
}

Output:
Reverse String is ahawhsuK hsemU

import java.io.BufferedReader;
class FindMinMaxString {
public static void main(String args[]) {
findMethod("My name is Umesh Kushwaha");
}
static public void findMethod(String s) {
String str = s + " ";
char ch = ' ';
int len = str.length(), l = 0;
int min = len, max = 0;
String shortest_word = "", longest_word = "", word = "";
for (int i = 0; i < len; i++) {
ch = str.charAt(i);
if (ch != ' ') {
word += ch;
} //if ends
else {
l = word.length();
if (l < min) {
min = l;
shortest_word = word;
} //if ends
if (l > max) {
max = l;
longest_word = word;
}
word = "";
}
}
System.out.println("Shortest word = " + shortest_word + " with length " + min);
System.out.println("Longest word = " + longest_word + " with length " + max);
}
}

Output:
Shortest word = My with length 2
Longest word = Kushwaha with length 8

Example.

Enter your name
Umesh Kumar Kushwaha
Initials are U.K.K.

import java.io.BufferedReader;
import java.io.IOException;
import java.io.InputStreamReader;
class InitialName {
public static void main(String args[]) throws IOException {
BufferedReader br = new BufferedReader(new InputStreamReader(System.in));
System.out.println("Enter your name");
String s = br.readLine(), s1 = "";
s = " " + s;
int len = s.length();
char a;
for (int i = 0; i < len; i++) {
a = s.charAt(i);
if (a == ' ') {
s1 = s1 + s.charAt(i + 1) + ".";
}
}
System.out.println("Initials are " + s1);
}
}

Output:
Enter your name
Umesh Kumar Kushwaha
Initials are U.K.K.

class CalculateAscii {
public static void main(String args[]) {
word("Umesh Kushwaha");
}
static void word(String s) {
int len = s.length();
int a;
char a1;
for (int i = 0; i < len; i++) {
a1 = s.charAt(i);
a = a1;
System.out.println(a1 + "–>" + a);
}
}
}

Output:

U–>85
m–>109
e–>101
s–>115
h–>104
–>32
K–>75
u–>117
s–>115
h–>104
w–>119
a–>97
h–>104
a–>97

import java.io.BufferedReader;
import java.io.IOException;
import java.io.InputStreamReader;
import java.util.logging.Level;
import java.util.logging.Logger;

class CountFrequencyOfWord {
public static void main(String args[]) {
try {
input();
} catch (IOException ex) {
Logger.getLogger(CountFrequencyOfWord .class.getName()).log(Level.SEVERE, null, ex);
}
}
static void input() throws IOException {
BufferedReader br = new BufferedReader(new InputStreamReader(System.in));
System.out.println("Enter a sentence");
String s = br.readLine();
System.out.println("Enter the letter ");
char a = (char) br.read();
int len = s.length();
int c = 0;
char x;
for (int i = 0; i < len; i++) {
x = Character.toLowerCase(s.charAt(i));
if (x == a)
c = c + 1;
}
System.out.println("Frequency of the letter " + a + " in the sentence " + s + " is " + c);
}
}

Output:

Enter a sentence
Hi my name is umesh
Enter the letter
m
Frequency of the letter m in the sentence "Hi my name is umesh" is 3

class RemoveDuplicate {
public static void main(String args[]) {
remove("123aa bbbcc c2589 99oppq rtyyy");
}
static void remove(String s) {
int l = s.length();
int c;
String org = s, s1 = "";
for (int i = 0; i < (l - 1); i++) {
s1 = s.substring(0, i + 1);
c = 0;
for (int j = i + 1; j < l; j++) {
if (s.charAt(i) == s.charAt(j)) {
c++;
continue;
} else
s1 = s1 + s.charAt(j);
}
s = s1;
s1 = "";
if (c > 0)
l -= c;
}
System.out.println("Original String:" + org);
System.out.println("String after removing duplicates: " + s);
}
}

Output:

Original String:123aa bbbcc c2589 99oppq rtyyy

String after removing duplicates: 123a bc589opqrty

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