String examples & JdbcBundle examples in Java

1. StringTest – (string pool behavior test)

class StringTest {

public static void main(String[] args) {

String s1 = new String("You cannot change me");

String s2 = new String("You cannot change me");

System.out.println(s1 == s2);// false

String s3 = "You cannot change me";

System.out.println(s1 == s3);// false

String s4 = "You cannot change me";

System.out.println(s3 == s4);// true

String s5 = "You cannot" + " change me";

System.out.println(s4 == s5);// true

String s6 = "You cannot";

String s7 = s6 + " change me";

System.out.println(s4 == s7);// false

final String s8 = "You cannot";

System.out.println(s6 == s8);// true

String s9 = s8 + " change me";

System.out.println(s4 == s9);// true

}

}

2. CountWords – Use Java 8 stream()

import java.util.Scanner;

public class CountWords {

    public static void main(String[] args) {

        Scanner sc = new Scanner(System.in);

        System.out.println("Please enter string: ");

        String str = sc.nextLine();

        long wordCount = str.trim().isEmpty() ? 0 :

                Arrays.stream(str.trim().split("\\s+")).count();

        System.out.println("Word count is = " + wordCount);

    }

}

Sample Output:

Please enter string:

Java is platform independent

Word count is = 4

3)CountWordsUsingString.java using StringTokenizer 

import java.util.Scanner;
import java.util.StringTokenizer;

public class CountWordsUsingString {

public static void main(String[] args) {
Scanner sc = new Scanner(System.in);
System.out.println("Please enter string: ");
String st = sc.nextLine();
int count = 0;
StringTokenizer stk = new StringTokenizer(st, " ");
while (stk.hasMoreTokens()) {
String token = stk.nextToken();
count++;
}
System.out.println("Number of words are: " + count);
}
}

4)CountCharacterUsingHashMap.java

import java.util.Map;

import java.util.Scanner;

import java.util.function.Function;

import java.util.stream.Collectors;

public class CountCharacterUsingHashMap {

    public static void main(String[] args) {

        Scanner sc = new Scanner(System.in);

        System.out.println("Please enter string: ");

        String str = sc.nextLine();

        Map<Character, Long> charCount = str.chars()

            .mapToObj(c -> (char) c)

            .collect(Collectors.groupingBy(Function.identity(), Collectors.counting()));

        System.out.println("No of Characters are : " + charCount);

    }

}

 5. CountSelectedWord – Java 8 using Collectors

import java.util.*;

import java.util.function.Function;

import java.util.stream.Collectors;

public class CountSelectedWord {

    public static void main(String[] args) {

        String str = "java java android android java example";

        String selectedWord = "java";

        Map<String, Long> wordFreq = Arrays.stream(str.split("\\s+"))

            .collect(Collectors.groupingBy(Function.identity(), Collectors.counting()));

        System.out.println(selectedWord + " occurs " + wordFreq.getOrDefault(selectedWord, 0L) + " times.");

    }

}

6. CountSelectedCharacter – Java 8 with Streams

import java.util.*;

import java.util.function.Function;

import java.util.stream.Collectors;

public class CountSelectedCharacter {

    public static void main(String[] args) {

        String str = "Count Selected Character example in java";

        char selectedChar = 'C';

        Map<Character, Long> freqMap = str.toUpperCase().chars()

            .mapToObj(c -> (char) c)

            .collect(Collectors.groupingBy(Function.identity(), Collectors.counting()));

        System.out.println(selectedChar + " occurs " + freqMap.getOrDefault(selectedChar, 0L) + " times.");

    }

}

7.stringreplace – Using replaceAll()

class StringReplace {

    public static void main(String[] args) {

        String s = "swamy narayana raju";

        String replaced = s.replaceAll("", "\n");

        System.out.println(replaced);

    }

}

8. ReverseString

class ReverseString

{

      public static void main(String[] args)

      {

            String s="swamy";

            String s1=" ";

            for(int i=s.length()-1;i>=0;i--)

            {

                  s1=s1+s.charAt(i);

                 

            }

       System.out.println(s1);

     String reversed = new StringBuilder(input).reverse().toString();

        System.out.println(reversed);

      }

}

 ======================================

 //StringPalindrome.java

import java.util.*;

public class StringPalindrome {

    public static void main(String[] args) {

        Scanner sc = new Scanner(System.in);

        System.out.println("Please enter string: ");

        String st = sc.nextLine();

        String rev = new StringBuilder(st).reverse().toString();

        if (st.equals(rev))

            System.out.println(st + " is a palindrome.");

        else

            System.out.println(st + " is not a palindrome.");

    }

}

 ============================================

import java.util.Arrays; import java.util.stream.Collectors; class EachWordReverse { public static void main(String[] args) { String input = "swamy good boy"; String result = Arrays.stream(input.split(" ")) .map(word -> new StringBuilder(word).reverse().toString()) .collect(Collectors.joining(" ")); System.out.println(result); } }

============================================

import java.util.Arrays; import java.util.Collections; class AllWordsReverse { public static void main(String[] args) { String input = "swamy good boy"; String[] words = input.split(" "); Collections.reverse(Arrays.asList(words)); System.out.println(String.join(" ", words)); } }

  ======================================

class StringToken { public static void main(String[] args) { String s = "swamy*good*boy"; Arrays.stream(s.split("\\*")).forEach(System.out::println); } }

 ======================================

public class Token { public static void main(String[] args) { String s = "www.microsoft007.in"; Arrays.stream(s.split("\\.")).forEach(System.out::println); } }

 ==================================

import java.io.File;

class filecreat
{
public static void main(String[] args) throws Exception
{
File f = new File("cba.txt");
System.out.println(f.exists()); // false at first time.
f.createNewFile();
System.out.println(f.exists()); // true
}
}

 ====================================

class StaticDemo

{

static int i = m1();

public static int m1()

{

System.out.println("Hello ....I am able to print");

System.exit(0);

return 1;

}

}
 ====================================

import java.io.FileInputStream;
import java.io.FileOutputStream;
import java.io.ObjectInputStream;
import java.io.ObjectOutputStream;
import java.io.Serializable;

class Dog implements Serializable
{
transient Cat c = new Cat();
}
class Cat
{
int j = 20;
}
class SerializeDemo
{
public static void main(String arg[]) throws Exception
{
Dog d = new Dog();
System.out.println("Before Serialization:" + d);
FileOutputStream fos = new FileOutputStream("abc.ser");
ObjectOutputStream oos = new ObjectOutputStream(fos);
oos.writeObject(d);
FileInputStream fis = new FileInputStream("abc.ser");
ObjectInputStream ois = new ObjectInputStream(fis);
Dog d1 = (Dog) ois.readObject();
System.out.println(d1);
}
}
 ======================

//prop1.java

import java.io.FileInputStream;
import java.io.FileNotFoundException;
import java.util.Properties;

class prop1
{
public static void main(String[] args)
{
try
{
Properties p = new Properties();
String pfile;
FileInputStream fis = new FileInputStream("pfile");
p.load(fis);
String sno = p.getProperty("stno");
String name = p.getProperty("sname");
String marks = p.getProperty("smarks");
System.out.println("Student number" + sno);
System.out.println("Student name" + name);
System.out.println("Student marks" + marks);
fis.close();
}
catch (ArrayIndexOutOfBoundsException ae)
{
System.err.println("plese enter properties file");
}
catch (FileNotFoundException fe)
{
System.err.println("the properties file id not found,pleace enter correct");
}
catch (Exception e)
{
System.err.println(e);
}
}
}
 =====================================

import java.io.File;
import java.io.FileWriter;

class filewrit
{
public static void main(String arg[]) throws Exception
{
File f = new File("pongal.txt");
System.out.println(f.exists());// false
FileWriter fw = new FileWriter(f, true);
System.out.println(f.exists());
fw.write(97);
fw.write("run\nsoftware\n");
char[] ch1 = { 'a', 'b', 'c' };
fw.write(ch1);
fw.flush();
fw.close();
}
}

 =======================================

import java.io.File;
import java.io.FileReader;

class fileread
{
public static void main(String arg[]) throws Exception
{
File f = new File("pongal.txt");
FileReader fr = new FileReader(f);
System.out.println(fr.read());
char[] ch2 = new char[(int) (f.length())];
System.out.println(ch2.length);
fr.read(ch2);
for (char ch1 : ch2)
{
System.out.print(ch1);
}
}
}

 =========================================

final class Immutable

{

private int i;

      Immutable(int i)

      {

            this.i=i;

      }

      public Immutable instance(int i)

      {

            if(this.i==i)

            {

                  return this;

            }

            else

            {

                  Immutable k=new Immutable(i);

                  return k;

            }

      }

      public static void main(String[] args)

      {

            Immutable im1=new Immutable(10);

            Immutable im2=im1.instance(10);

            Immutable im3=im1.instance(100);

        System.out.println(im1);

         System.out.println(im2);

             System.out.println(im3);

             /*System.out.println(im1.hashCode());

         System.out.println(im2.hashCode());

             System.out.println(im3.hashCode());*/

         System.out.println(im1==im2);

             System.out.println(im1==im3);

      }

}

 ==================================

import java.io.FileInputStream;

import java.sql.*;

import java.util.Properties;

public class JdbcBundleTest {

    public static void main(String[] args) throws Exception {

        Properties props = new Properties();

        try (FileInputStream fis = new FileInputStream("jdbcdata.properties")) {

            props.load(fis);

        }

        Class.forName(props.getProperty("jdbc.driver"));

        try (Connection con = DriverManager.getConnection(

                    props.getProperty("jdbc.url"),

                    props.getProperty("jdbc.user"),

                    props.getProperty("jdbc.pwd"));

             Statement stmt = con.createStatement();

             ResultSet rs = stmt.executeQuery("SELECT * FROM sathya124")) {

            while (rs.next()) {

                System.out.println(rs.getInt(1) + " " + rs.getString(2));

            }

        }

    }

}

#jdbcdata.properties

jdbc.driver=oracle.jdbc.OracleDriver

jdbc.url=jdbc:oracle:thin:@localhost:1521:xe

jdbc.user=scott

jdbc.pwd=tiger