Java program for linear search
import java.util.Scanner;
class LinearSearch
{
public static void main(String args[])
{
int c, n, search, array[];
Scanner in = new Scanner(System.in);
System.out.println("Enter number of elements");
n = in.nextInt();
array = new int[n];
System.out.println("Enter " + n + " integers");
for (c = 0; c < n; c++)
array[c] = in.nextInt();
System.out.println("Enter value to find");
search = in.nextInt();
for (c = 0; c < n; c++)
{
if (array[c] == search) /* Searching element is present */
{
System.out.println(search + " is present at location " + (c + 1) + ".");
break;
}
}
if (c == n) /* Searching element is absent */
System.out.println(search + " is not present in array.");
}
}
Java program for binary search
import java.util.Scanner;
class BinarySearch
{
public static void main(String args[])
{
int c, first, last, middle, n, search, array[];
Scanner in = new Scanner(System.in);
System.out.println("Enter number of elements");
n = in.nextInt();
array = new int[n];
System.out.println("Enter " + n + " integers");
for (c = 0; c < n; c++)
array[c] = in.nextInt();
System.out.println("Enter value to find");
search = in.nextInt();
first = 0;
last = n - 1;
middle = (first + last)/2;
while( first <= last )
{
if ( array[middle] < search )
first = middle + 1;
else if ( array[middle] == search )
{
System.out.println(search + " found at location " + (middle + 1) + ".");
break;
}
else
last = middle - 1;
middle = (first + last)/2;
}
if ( first > last )
System.out.println(search + " is not present in the list.\n");
}
}
Java program to display date and time, print date and time using
java program
import java.util.*;
class GetCurrentDateAndTime
{
public static void main(String args[])
{
int day, month, year;
int second, minute, hour;
GregorianCalendar date = new GregorianCalendar();
day = date.get(Calendar.DAY_OF_MONTH);
month = date.get(Calendar.MONTH);
year = date.get(Calendar.YEAR);
second = date.get(Calendar.SECOND);
minute = date.get(Calendar.MINUTE);
hour = date.get(Calendar.HOUR);
System.out.println("Current date is "+day+"/"+(month+1)+"/"+year);
System.out.println("Current time is "+hour+" : "+minute+" : "+second);
}
}
Java program to generate random numbers
import java.util.*;
class RandomNumbers {
public static void main(String[] args) {
int c;
Random t = new Random();
// random integers in [0, 100]
for (c = 1; c <= 10; c++) {
System.out.println(t.nextInt(100));
}
}
}
Java program to perform garbage collection
mport java.util.*;
class GarbageCollection
{
public static void main(String s[]) throws Exception
{
Runtime rs = Runtime.getRuntime();
System.out.println("Free memory in JVM before Garbage Collection = "+rs.freeMemory());
rs.gc();
System.out.println("Free memory in JVM after Garbage Collection = "+rs.freeMemory());
}
}
Java program to get ip address
import java.net.InetAddress;
class IPAddress
{
public static void main(String args[]) throws Exception
{
System.out.println(InetAddress.getLocalHost());
}
}
Java program to multiply two matrices
import java.util.Scanner;
class MatrixMultiplication
{
public static void main(String args[])
{
int m, n, p, q, sum = 0, c, d, k;
Scanner in = new Scanner(System.in);
System.out.println("Enter the number of rows and columns of first matrix");
m = in.nextInt();
n = in.nextInt();
int first[][] = new int[m][n];
System.out.println("Enter the elements of first matrix");
for ( c = 0 ; c < m ; c++ )
for ( d = 0 ; d < n ; d++ )
first[c][d] = in.nextInt();
System.out.println("Enter the number of rows and columns of second matrix");
p = in.nextInt();
q = in.nextInt();
if ( n != p )
System.out.println("Matrices with entered orders can't be multiplied with each other.");
else
{
int second[][] = new int[p][q];
int multiply[][] = new int[m][q];
System.out.println("Enter the elements of second matrix");
for ( c = 0 ; c < p ; c++ )
for ( d = 0 ; d < q ; d++ )
second[c][d] = in.nextInt();
for ( c = 0 ; c < m ; c++ )
{
for ( d = 0 ; d < q ; d++ )
{
for ( k = 0 ; k < p ; k++ )
{
sum = sum + first[c][k]*second[k][d];
}
multiply[c][d] = sum;
sum = 0;
}
}
System.out.println("Product of entered matrices:-");
for ( c = 0 ; c < m ; c++ )
{
for ( d = 0 ; d < q ; d++ )
System.out.print(multiply[c][d]+"\t");
System.out.print("\n");
}
}
}
}
Java program to open Notepad
import java.util.*;
import java.io.*;
class Notepad {
public static void main(String[] args) {
Runtime rs = Runtime.getRuntime();
try {
rs.exec("notepad");
}
catch (IOException e) {
System.out.println(e);
}
}
}
Finding the Big number
mport java.util.Scanner;
class Tables
{
public static void main(String args[])
{
int a, b, c, d;
System.out.println("Enter range of numbers to print their multiplication table");
Scanner in = new Scanner(System.in);
a = in.nextInt();
b = in.nextInt();
for (c = a; c <= b; c++) {
System.out.println("Multiplication table of "+c);
for (d = 1; d <= 10; d++) {
System.out.println(c+"*"+d+" = "+(c*d));
}
}
}
}
Printing the stars
class Stars
{
public static void main(String[] args) {
int row, numberOfStars;
for (row = 1; row <= 10; row++) {
for(numberOfStars = 1; numberOfStars <= row; numberOfStars++) {
System.out.print("*");
}
System.out.println(); // Go to next line
}
}
}
Printing
the Alphabetical order
class Alphabets
{
public static void main(String args[])
{
char ch;
for( ch = 'a' ; ch <= 'z' ; ch++ )
System.out.println(ch);
}
}
Finding big number
import java.util.Scanner;
import java.math.BigInteger;
class AddingLargeNumbers {
public static void main(String[] args) {
String number1, number2;
Scanner in = new Scanner(System.in);
System.out.println("Enter first large number");
number1 = in.nextLine();
System.out.println("Enter second large number");
number2 = in.nextLine();
BigInteger first = new BigInteger(number1);
BigInteger second = new BigInteger(number2);
System.out.println("Addition = " + first.add(second));
}
}
How to
get line count from a string?
package
com.java2novice.string;
public class
MyStringLineCounter {
public
static int getLineCount(String text){
return
text.split("[\n|\r]").length;
}
public
static void main(String a[]){
String
str = "line1\nline2\nline3\rline4";
System.out.println(str);
int
count = getLineCount(str);
System.out.println("line
count: "+count);
}
}
Write a
program to find perfect number or not.
public class IsPerfectNumber
{
public
boolean isPerfectNumber(int number){
int
temp = 0;
for(int
i=1;i<=number/2;i++){
if(number%i
== 0){
temp
+= i;
}
}
if(temp
== number){
System.out.println("It
is a perfect number");
return
true;
}
else {
System.out.println("It
is not a perfect number");
return
false;
}
}
public
static void main(String a[]){
IsPerfectNumber
ipn = new IsPerfectNumber();
System.out.println("Is
perfect number: "+ipn.isPerfectNumber(28));
}
}
Write a
program to find the sum of the first 1000 prime numbers.
package com.primesum;
public class Main {
public
static void main(String args[]){
int
number = 2;
int
count = 0;
long
sum = 0;
while(count
< 1000){
if(isPrimeNumber(number)){
sum
+= number;
count++;
}
number++;
}
System.out.println(sum);
}
private
static boolean isPrimeNumber(int number){
for(int
i=2; i<=number/2; i++){
if(number
% i == 0){
return
false;
}
}
return
true;
}
}
Write a
program to convert string to number without using Integer.parseInt() metho
public class
MyStringToNumber {
public
static int convert_String_To_Number(String numStr){
char
ch[] = numStr.toCharArray();
int
sum = 0;
//get
ascii value for zero
int
zeroAscii = (int)'0';
for(char
c:ch){
int
tmpAscii = (int)c;
sum
= (sum*10)+(tmpAscii-zeroAscii);
}
return
sum;
}
public
static void main(String a[]){
System.out.println("\"3256\"
== "+convert_String_To_Number("3256"));
System.out.println("\"76289\"
== "+convert_String_To_Number("76289"));
System.out.println("\"90087\"
== "+convert_String_To_Number("90087"));
}
}
Write a
program to get a line with max word count from the given file.
import
java.io.BufferedReader;
import
java.io.DataInputStream;
import
java.io.FileInputStream;
import
java.io.FileNotFoundException;
import
java.io.IOException;
import
java.io.InputStreamReader;
import
java.util.ArrayList;
import java.util.List;
public class
MaxWordCountInLine {
private
int currentMaxCount = 0;
private
List<String> lines = new ArrayList<String>();
public
void readMaxLineCount(String fileName){
FileInputStream
fis = null;
DataInputStream
dis = null;
BufferedReader
br = null;
try
{
fis
= new FileInputStream(fileName);
dis
= new DataInputStream(fis);
br
= new BufferedReader(new InputStreamReader(dis));
String
line = null;
while((line
= br.readLine()) != null){
int
count = (line.split("\\s+")).length;
if(count
> currentMaxCount){
lines.clear();
lines.add(line);
currentMaxCount
= count;
}
else if(count == currentMaxCount){
lines.add(line);
}
}
}
catch (FileNotFoundException e) {
e.printStackTrace();
}
catch (IOException e) {
e.printStackTrace();
}
finally{
try{
if(br
!= null) br.close();
}catch(Exception
ex){}
}
}
public
int getCurrentMaxCount() {
return
currentMaxCount;
}
public
void setCurrentMaxCount(int currentMaxCount) {
this.currentMaxCount
= currentMaxCount;
}
public
List<String> getLines() {
return
lines;
}
public
void setLines(List<String> lines) {
this.lines
= lines;
}
public
static void main(String a[]){
MaxWordCountInLine
mdc = new MaxWordCountInLine();
mdc.readMaxLineCount("/Users/ngootooru/MyTestFile.txt");
System.out.println("Max
number of words in a line is: "+mdc.getCurrentMaxCount());
System.out.println("Line
with max word count:");
List<String>
lines = mdc.getLines();
for(String
l:lines){
System.out.println(l);
}
}
}
Find out
middle index where sum of both ends are equal.
public class
FindMiddleIndex {
public
static int findMiddleIndex(int[] numbers) throws Exception {
int
endIndex = numbers.length - 1;
int
startIndex = 0;
int
sumLeft = 0;
int
sumRight = 0;
while
(true) {
if
(sumLeft > sumRight) {
sumRight
+= numbers[endIndex--];
}
else {
sumLeft
+= numbers[startIndex++];
}
if
(startIndex > endIndex) {
if
(sumLeft == sumRight) {
break;
}
else {
throw
new Exception(
"Please
pass proper array to match the requirement");
}
}
}
return
endIndex;
}
public
static void main(String a[]) {
int[]
num = { 2, 4, 4, 5, 4, 1 };
try
{
System.out.println("Starting
from index 0, adding numbers till index "
+
findMiddleIndex(num) + " and");
System.out.println("adding
rest of the numbers can be equal");
}
catch (Exception ex) {
System.out.println(ex.getMessage());
}
}
}
Write a
program to convert decimal number to binary format
public class
DecimalToBinary {
public
void printBinaryFormat(int number){
int
binary[] = new int[25];
int
index = 0;
while(number
> 0){
binary[index++]
= number%2;
number
= number/2;
}
for(int
i = index-1;i >= 0;i--){
System.out.print(binary[i]);
}
}
public
static void main(String a[]){
DecimalToBinary
dtb = new DecimalToBinary();
dtb.printBinaryFormat(25);
}
}
Write a
program to find maximum repeated words from a file
import
java.io.BufferedReader;
import
java.io.DataInputStream;
import
java.io.FileInputStream;
import
java.io.FileNotFoundException;
import
java.io.IOException;
import
java.io.InputStreamReader;
import
java.util.ArrayList;
import
java.util.Collections;
import
java.util.Comparator;
import
java.util.HashMap;
import java.util.List;
import java.util.Map;
import java.util.Set;
import
java.util.StringTokenizer;
import java.util.Map.Entry;
public class
MaxDuplicateWordCount {
public
Map<String, Integer> getWordCount(String fileName){
FileInputStream
fis = null;
DataInputStream
dis = null;
BufferedReader
br = null;
Map<String,
Integer> wordMap = new HashMap<String, Integer>();
try
{
fis
= new FileInputStream(fileName);
dis
= new DataInputStream(fis);
br
= new BufferedReader(new InputStreamReader(dis));
String
line = null;
while((line
= br.readLine()) != null){
StringTokenizer
st = new StringTokenizer(line, " ");
while(st.hasMoreTokens()){
String
tmp = st.nextToken().toLowerCase();
if(wordMap.containsKey(tmp)){
wordMap.put(tmp,
wordMap.get(tmp)+1);
}
else {
wordMap.put(tmp,
1);
}
}
}
}
catch (FileNotFoundException e) {
e.printStackTrace();
}
catch (IOException e) {
e.printStackTrace();
}
finally{
try{if(br
!= null) br.close();}catch(Exception ex){}
}
return
wordMap;
}
public
List<Entry<String, Integer>> sortByValue(Map<String, Integer>
wordMap){
Set<Entry<String,
Integer>> set = wordMap.entrySet();
List<Entry<String,
Integer>> list = new ArrayList<Entry<String, Integer>>(set);
Collections.sort(
list, new Comparator<Map.Entry<String, Integer>>()
{
public
int compare( Map.Entry<String, Integer> o1, Map.Entry<String,
Integer> o2 )
{
return
(o2.getValue()).compareTo( o1.getValue() );
}
}
);
return
list;
}
public
static void main(String a[]){
MaxDuplicateWordCount
mdc = new MaxDuplicateWordCount();
Map<String,
Integer> wordMap = mdc.getWordCount("C:/MyTestFile.txt");
List<Entry<String,
Integer>> list = mdc.sortByValue(wordMap);
for(Map.Entry<String,
Integer> entry:list){
System.out.println(entry.getKey()+"
==== "+entry.getValue());
}
}
}
Write a
program to find sum of each digit in the given number using recursion
public class
MyNumberSumRec {
int
sum = 0;
public
int getNumberSum(int number){
if(number
== 0){
return
sum;
}
else {
sum
+= (number%10);
getNumberSum(number/10);
}
return
sum;
}
public
static void main(String a[]){
MyNumberSumRec
mns = new MyNumberSumRec();
System.out.println("Sum
is: "+mns.getNumberSum(223));
}
}
Write a
program to find the given number is Armstrong number or not?
public class
MyArmstrongNumber {
public
boolean isArmstrongNumber(int number){
int
tmp = number;
int
noOfDigits = String.valueOf(number).length();
int
sum = 0;
int
div = 0;
while(tmp
> 0)
{
div
= tmp % 10;
int
temp = 1;
for(int
i=0;i<noOfDigits;i++){
temp
*= div;
}
sum
+= temp;
tmp
= tmp/10;
}
if(number
== sum) {
return
true;
}
else {
return
false;
}
}
public
static void main(String a[]){
MyArmstrongNumber
man = new MyArmstrongNumber();
System.out.println("Is
371 Armstrong number? "+man.isArmstrongNumber(371));
System.out.println("Is
523 Armstrong number? "+man.isArmstrongNumber(523));
System.out.println("Is
153 Armstrong number? "+man.isArmstrongNumber(153));
}
}
Write a
program to check the given number is binary number or not?
public class MyBinaryCheck
{
public
boolean isBinaryNumber(int binary){
boolean
status = true;
while(true){
if(binary
== 0){
break;
}
else {
int
tmp = binary%10;
if(tmp
> 1){
status
= false;
break;
}
binary
= binary/10;
}
}
return
status;
}
public
static void main(String a[]){
MyBinaryCheck
mbc = new MyBinaryCheck();
System.out.println("Is
1000111 binary? :"+mbc.isBinaryNumber(1000111));
System.out.println("Is
10300111 binary? :"+mbc.isBinaryNumber(10300111));
}
}
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