package temp;
import java.io.File;
import java.io.FileInputStream;
import java.io.FileNotFoundException;
import java.io.FileReader;
import java.io.FileWriter;
import java.io.IOException;
import java.util.ArrayList;
import java.util.Arrays;
import java.util.HashMap;
import java.util.Map;
import java.util.Properties;
import java.util.Scanner;
import org.json.simple.JSONObject;
import org.json.simple.parser.JSONParser;
import org.json.simple.parser.ParseException;
import org.testng.annotations.Test;
public class javaExamples {
// @Test
public void swapNumbers() {
int a = 10, b = 20;
b = (a + b) - (a = b);
System.out.println(a + "Values" + b);
// using third variable
int i = 10, j = 20, k = 0;
k = i;
i = j;
j = k;
System.out.println(i + " I Value >>" + j + " J Value ");
}
// @Test
public void reverseNumbers() {
int num = 123456;
int rev = 0;
while (num > 0) {
rev = rev * 10 + num % 10;
num = num / 10;
}
System.out.println(rev);
// Second Way
int num1 = 1234;
StringBuilder sb1 = new StringBuilder(String.valueOf(num1));
System.out.println(sb1.reverse());
// Third Way
StringBuffer sb = new StringBuffer(String.valueOf(num1));
System.out.println(sb.reverse());
}
// @Test
public void reverseString() {
String str = "RAVI";
String rev = "";
int len = str.length();
for (int i = len - 1; i > 0; i--) {
rev = rev + str.charAt(i);
}
System.out.println(rev);
// Second Way
StringBuilder sb = new StringBuilder(str);
System.out.println(sb.reverse());
// Third Way
StringBuffer sb1 = new StringBuffer(str);
System.out.println(sb1.reverse());
}
// @Test
public void palindromeNumber() {
int num = 123454321;
int original = num;
int rev = 0;
while (num > 0) {
rev = rev * 10 + num % 10;
num = num / 10;
}
System.out.println(rev);
if (original == rev)
System.out.println("Provided Number is Palindrome Number");
else
System.out.println("Provided Number is NOT a Palindrome Number");
}
// @Test
public void palindromeString() {
String str = "MADAM";
String original = str;
int len = str.length();
String rev = "";
for (int i = len - 1; i >= 0; i--) {
rev = rev + str.charAt(i);
}
System.out.println(rev);
if (original.equals(rev))
System.out.println("Provided String is Palindrome String");
else
System.out.println("Provided String is NOT a Palindrome String");
System.out.println("");
}
// @Test
public void countNumberofDigits() {
int num = 1234534;
int count = 0;
while (num > 0) {
num = num / 10;
count++;
}
System.out.println(count);
}
// @Test
public void sumOfDigits() {
int num = 12345;
int sum = 0;
while (num > 0) {
sum = sum + num % 10;
num = num / 10;
}
System.out.println(sum);
}
// @Test
public void oddEvenNumbers() {
int num = 123456719, temp = 0;
ArrayList<Integer> even = new ArrayList<>();
ArrayList<Integer> odd = new ArrayList<>();
while (num > 0) {
temp = num % 10;
num = num / 10;
if (temp % 2 == 0)
even.add(temp);
else
odd.add(temp);
}
System.out.println(even);
System.out.println(odd);
}
// @Test
public void largetNumber() {
int a = 10, b = 20, c = 30;
int lar1 = (a > b) ? a : b;
int lar2 = (lar1 > c) ? lar1 : c;
System.out.println(lar2);
}
// @Test
public void fibonacciSeries() {
int a = 0, b = 1, temp = 0;
System.out.print(a + " " + b + " ");
for (int i = 0; i < 10; i++) {
temp = a + b;
a = b;
b = temp;
System.out.print(temp + " ");
}
System.out.println("");
}
// @Test
public void printStarsIncrease() {
int num = 5;
for (int i = 1; i <= num; i++) {
for (int j = 0; j < i; j++) {
System.out.print("*");
}
System.out.println();
}
}
// @Test
public void findMaxMinArray() {
int[] array = { 10, 133, 54, 199, 5, 4, 3, 2, 1 };
int max = 0, min = Integer.MAX_VALUE;
for (int value : array) {
if (value > max)
max = value;
if (value < min)
min = value;
}
System.out.println(max);
System.out.println(min);
}
// @Test
public void equalArray() {
int arr1[] = { 2, 3, 5 };
int arr2[] = { 5, 3, 2 };
Arrays.sort(arr1);
Arrays.sort(arr2);
System.out.println(Arrays.toString(arr2));
boolean status = true;
System.out.println(Arrays.toString(arr1));
if (arr1.length == arr2.length) {
for (int i = 0; i < arr1.length; i++)
if (arr1[i] != arr2[i]) {
status = false;
}
} else
status = false;
if (status)
System.out.println("Arrays are equal");
else
System.out.println("Arrays are NOT equal");
// Second Way
status = Arrays.equals(arr1, arr2);
if (status)
System.out.println("Arrays are equal");
else
System.out.println("Arrays are NOT equal");
}
// @Test
public void evenOddArray() {
int[] array = { 12, 4, 6, 7, 9, 3, 5, 3, 4, 1 };
ArrayList<Integer> even = new ArrayList<>();
ArrayList<Integer> odd = new ArrayList<>();
for (int value : array) {
if (value % 2 == 0)
even.add(value);
else
odd.add(value);
}
System.out.println(even);
System.out.println(odd);
}
// @Test
public void sumofArryNumbers() {
int[] num = { 2, 5, 9, 3, 5 };
int sum = 0;
for (int value : num)
sum = sum + value % 10;
System.out.println(sum);
}
// @Test
public void CompareTwoStrings() {
String str = "RAVI", str1 = "Ravi";
int result = str.compareTo(str1);
if (result == 0)
System.out.println("Stings are same");
else
System.out.println("Strings are NOT same");
result = str.compareToIgnoreCase(str1);
if (result == 0)
System.out.println("Stings are same");
else
System.out.println("Strings are NOT same");
}
// @Test
public void splitExample() {
String str = "I am Ravi";
String[] str1 = str.split(" ");
System.out.println(str1[0]);
System.out.println(str1[1]);
System.out.println(str1[2]);
}
// @Test
public void replaceExample() {
String str = "Hello2World2Ravi";
str = str.replace("2", " ");
System.out.println(str);
}
// @Test
public void replaceAll() {
String str = "ldjsfldjf*^*&*^*^*&()*&()";
str = str.replaceAll("[^a-zA-Z0-9]", "");
System.out.println(str); // it will exclude special chars
str = "ldjsfldjf*^*&*^*^*&()*&()";
str = str.replaceAll("[a-zA-Z0-9]", "");
System.out.println(str); // it will display only special chars
}
// @Test
public void avaragetElementsArray() {
double[] num = { 2.15, 4.55, 6.7, 3.22, 5 };
double avg = 0.00;
double sum = 0.0;
for (double value : num) {
sum = sum + value;
}
int len = num.length;
avg = sum / len;
System.out.println(avg);
}
// @Test
public void sortElementsArray() {
int[] num = { 1, 4, 77, 66, 44, 34, 3, 9, 99 };
System.out.println(Arrays.toString(num));
Arrays.sort(num);
System.out.println(Arrays.toString(num));
}
// @Test
public void smallestElementArray() {
int[] num = { 3, 6, 3, 2, 9, 1, 88, 33, 22, 55, 36 };
int smallNum = Integer.MAX_VALUE;
for (int i = 0; i < num.length; i++) {
if (smallNum > num[i]) {
smallNum = num[i];
}
}
System.out.println(smallNum);
}
// @Test
public void largestElementArray() {
int[] num = { 3, 6, 3, 2, 9, 1, 88, 33, 22, 55, 36 };
int largeNum = 0;
int secLargNum = 0;
for (int i = 0; i < num.length; i++) {
if (num[i] > largeNum) {
largeNum = num[i];
}
}
System.out.println(largeNum);
}
// @Test
public void subStringExample() {
String str = "RAVI KRISHNA SAI";
System.out.println(str.substring(9));
System.out.println(str.substring(4, 10));
System.out.println(str.subSequence(3, 10));
System.out.println(str.substring(3, 4));
}
// @Test
public void stringContainsExample() {
String str = "Testing Java";
if (str.contains("Java"))
System.out.println("String Contains the Java");
else
System.out.println("Java string is not there");
}
// @Test
public void trimExample() {
String str = " testing ";
str = str.trim();
System.out.println(str);
}
// @Test
public void arrayConvertToString() {
int[] num = { 33, 55, 77, 3, 5, 8, 7, 88 };
System.out.println(Arrays.toString(num));
}
// @Test
public void addNewNumberArray() {
Integer[] num = { 33, 55, 77, 3, 5, 8, 7, 88 };
ArrayList<Integer> newNum = new ArrayList<Integer>(Arrays.asList(num));
newNum.add(1);
System.out.println(newNum);
}
// @Test
public void toLowerCase() {
String str = "TESTING";
str = str.toLowerCase();
System.out.println(str);
}
// @Test
public void toUpperCase() {
String str = "testing";
str = str.toUpperCase();
System.out.println(str);
}
// @Test
public void indexOf() {
String str = "Testing";
int result = str.indexOf('s');
System.out.println(result);
}
// @Test
public void matches() {
String regex = "^J..a$";
boolean str = "Java".matches(regex);
if (str)
System.out.println("String matching");
else
System.out.println("String NOT matching");
}
// @Test
public void startsWith() {
String str = "Java is Best";
boolean result = str.startsWith("Java");
if (result)
System.out.println("String with Java");
else
System.out.println("String NOT with Java");
}
// @Test
public void endsWith() {
String str = "Java is Best";
boolean result = str.endsWith("Best");
if (result)
System.out.println("Ends with Best");
else
System.out.println("Ends NOT with Best");
}
// @Test
public void isEmpty() {
String str = "";
boolean result = str.isEmpty(); // is empty works as length of the String
// is blank works as empty or white space
if (result)
System.out.println("Empty String");
else
System.out.println("NOT Empty String");
}
// @Test
public void joinString() {
String str1 = "I";
String str2 = "love";
String str3 = "Java";
// join strings with space between them
String joinedStr = String.join(" ", str1, str2, str3);
System.out.println(joinedStr);
}
// @Test
public void replaceFirst() {
String str1 = "aabbaaac";
String str2 = "Learn223Java55@";
// regex for sequence of digits
String regex = "\\d+";
// the first occurrence of "aa" is replaced with "zz"
System.out.println(str1.replaceFirst("aa", "zz")); // zzbbaaac
// replace the first sequence of digits with a whitespace
System.out.println(str2.replaceFirst(regex, " ")); // Learn Java55@
}
// @Test
public void createWriteReadFile() throws IOException {
String myFileName = "test.txt";
String write = "url = https://www.google.com/;";
File fi = new File(myFileName);
boolean result = fi.createNewFile();
if (result) {
System.out.println("File is Created");
// Write to the file
FileWriter fw = new FileWriter(myFileName);
fw.write(write);
fw.close();
// Read file
Properties pro = new Properties();
FileInputStream Fis = new FileInputStream(myFileName);
pro.load(Fis);
System.out.println(pro.getProperty("url"));
}
}
// @Test
public void readJSonFileData() throws ParseException, FileNotFoundException, IOException {
JSONParser pars = new JSONParser();
Object obj = pars.parse(new FileReader("temp.json"));
JSONObject jobj = (JSONObject) obj;
String myURL = (String) jobj.get("url");
System.out.println(myURL);
}
// @Test
public void countNumberofLines() throws FileNotFoundException {
File file = new File("test.config");
Scanner sc = new Scanner(file);
int count = 0;
while (sc.hasNextLine()) {
sc.nextLine();
count++;
}
System.out.println("Number of Lines in File >> " + count);
}
// @Test
public void concatenateTwoArrays() {
int[] array1 = { 1, 2, 3 };
int[] array2 = { 4, 5, 6 };
int leng1 = array1.length;
int leng2 = array2.length;
int[] result = new int[leng1 + leng2];
System.arraycopy(array1, 0, result, 0, leng1);
System.arraycopy(array2, 0, result, leng1, leng2);
System.out.println(Arrays.toString(result));
}
//@Test
public void iterateHashMap() {
HashMap<Integer,String> HM = new HashMap<Integer,String>();
HM.put(2, "Sai");
HM.put(44, "Ravi");
HM.put(12, "Lucky");
for(Map.Entry me:HM.entrySet()) {
System.out.println("Key is: " + me.getKey() + " Value is >> " + me.getValue());
}
}
// @Test
public void duplicateCharsinString() {
String str = "Ravivi";
int count = 0, len = str.length();
char[] cha = str.toCharArray();
System.out.println("Duplicate characters are:");
for (int i = 0; i < len; i++) {
for (int j = i + 1; j < len; j++) {
if (cha[i] == cha[j]) {
System.out.println(cha[j]);
count++;
break;
}
}
}
}
/*
* armstrongNumber 153 = 1*1*1 + 5*5*5 + 3*3*3 = 1 + 125 + 27 = 153
* If you have a four-digit number lets say 1634 = 1*1*1*1 + 6*6*6*6 + 3*3*3*3 + 4*4*4*4 = 1 + 1296 + 81 + 256 = 1634
*/
@Test
public void armstrongNumber() {
int num = 1634;
int val = 1, armst=0;
while(num>0) {
val = num%10;
num = num/10;
armst = armst+(val*val*val*val);
}
System.out.println(armst);
}
// @Test
public void secondThirdLargEleArray() throws IOException, ParseException {
int temp, size;
int[] num = { 11, 22, 43, 56, 77, 3, 9, 67 };
size = num.length;
for (int i = 0; i < size; i++) {
for (int j = i + 1; j < size; j++) {
if (num[i] > num[j]) {
temp = num[i];
num[i] = num[j];
num[j] = temp;
}
}
}
System.out.println(Arrays.toString(num));
System.out.println(num[size - 2]); // second largest
System.out.println(num[size - 3]); // third largest
// Second Way
int array[] = { 10, 20, 25, 63, 96, 57 };
int size1 = array.length;
Arrays.sort(array);
System.out.println("sorted Array ::" + Arrays.toString(array));
int res = array[size1 - 2];
System.out.println("2nd largest element is ::" + res);
}
}
Java Examples
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