public class string_formatting_1 {

    public static void main(String[] args) {
        String s1 = "Hello";
        String s2 = "World";
        String s3 = "The day after tomorrow";
        String s4 = "Open 24 hours";
        String name = "Paul Valle";
        Double decimalNum = 45.6784;
        Integer bigNum = 123456789;

        Date date = new Date();

        System.out.println(s1 + " " + s2);

        String strConcat = s1.concat(" " + s2);
        System.out.println(strConcat);

        // Using printf and format (both are interchangeable)

        // %n = newline, you can also use %d, %f %e for numbers
        System.out.printf("I am %d years old %n", 100);
        System.out.printf("%,d (using , separator)", bigNum);

        System.out.format("I am %d years old %n", 100);
        System.out.format("%,d (using , separator)", bigNum);

        // use %s for strings
        System.out.printf("%20s (right justified) %n", name);
        System.out.printf("%-20s (left justified) %n", name);
        System.out.printf("%10.5s (padding.num of chars) %n", decimalNum);
        System.out.printf("%-10.5s (padding.num of chars) %n", decimalNum);

        System.out.format("%20s (right justified) %n", name);
        System.out.format("%-20s (left justified) %n", name);
        System.out.format("%10.5s (padding.num of chars) %n", decimalNum);
        System.out.format("%-10.5s (padding.num of chars) %n", decimalNum);

        // use locale
        Locale italian_locale = Locale.ITALIAN;
        System.out.printf(italian_locale, "The date is %tc %n", date);
        System.out.printf(Locale.US, "The date is %tc %n", date);

        System.out.format(italian_locale, "The date is %tc %n", date);
        System.out.format(Locale.US, "The date is %tc %n", date);
    }
}

public class string_formatting_lists_1 {

    public static void main(String[] args) {
        int[] a1 = {1,2,3,4,5};

        for (int i = 0; i < a1.length; i++) {
            System.out.println(a1[i]);
        }

        // don't print the last separator
        for (int i = 0; i < a1.length; i++) {
            System.out.print(a1[i]);
            if (i < a1.length - 1) {
                System.out.print(", ");
            }
        }
        System.out.println();

        // You have to keep track of the index yourself using a for loop
        int index = 0;
        for (int i : a1) {
            System.out.print(i);
            if (index != a1.length - 1) {
                System.out.print(", ");
            }
            index++;
        }
        System.out.println();

        // There are many ways here another way
        StringJoiner sj = new StringJoiner(", ");
        for (int i : a1)
        {
            sj.add(Integer.toString(i));
        }
        System.out.println(sj);

        // Very quick way
        System.out.println(String.join(", ", Arrays.toString(a1)));

        // Using lambda's
        String a2 = Arrays.stream(a1)
                .mapToObj(i -> Integer.toString(i))
                .collect(Collectors.joining(", "));
        System.out.println(a2);
    }
}

StringBuffer sb1 = new StringBuffer();              // this will have an initial capacity of 16 characters
StringBuffer sb2 = new StringBuffer(10);            // this will have a capacity of 10 characters

StringBuffer sb3 = new StringBuffer("Hello World!");  // the capacity will be string size 12 plus 16 = 32

System.out.println("StringBuffer sb3 is: " + sb3);    // Just use it like a String

StringBuffer sb = new StringBuffer("abcd");

System.out.println("Appends efgh to StringBuffer sb :" + sb.append("efgh");
System.out.println("StringBuffer sb is now: " + sb);

Note: There are 10 overloaded append methods which allow you to add various data type values

StringBuffer sb1 = new StringBuffer();
StringBuffer sb1 = new StringBuffer(10);
StringBuffer sb1 = new StringBuffer("Hello World");

System.out.prntln("StringBuffer sb1(character count): " + sb1);     // displays 0
System.out.prntln("StringBuffer sb2(character count): " + sb2);     // displays 0
System.out.prntln("StringBuffer sb3(character count): " + sb3);     // displays 11

System.out.prntln("StringBuffer sb1(capacity): " + sb1);     // displays 16
System.out.prntln("StringBuffer sb2(capacity): " + sb2);     // displays 10
System.out.prntln("StringBuffer sb3(capacity): " + sb3);     // displays 27

Note: increasing the size is a performance hit, so if you do change the StringBuffer make sure it has the capacity already so it does not need to grow

StringBuffer sb1 = new StringBuffer();
sb1.ensureCapacity(75);                 // minimum capacity will be 75 characters

Note: if the character length is greater then the method ensures a capacity that is the greater of the number specified as an argument or twice the original capacity plus 2.

## sb.delete(start position, end position)
StringBuffer sb = new StringBuffer("1234567890");

System.out.println("Inserted text into StringBuffer sb: " + sb.delete(4, 6));  / displays 12347890

## sb.insert(start, data type) there are many diffrent data types i.e boolean, char, String, etc
StringBuffer sb = new StringBuffer("1234567890");

System.out.println("Inserted text into StringBuffer sb: " + sb.insert(4, "----"));

Note: again the offset is zero based

StringBuffer sb1 = new StringBuffer();
StringBuffer sb2 = new StringBuffer(10);
StringBuffer sb3 = new StringBuffer("Hello World");

System.out.println("StringBuffer sb1: " + sb1.length());     // displays 0 
System.out.println("StringBuffer sb2: " + sb2.length());     // displays 0
System.out.println("StringBuffer sb3: " + sb3.length());     // displays 11

Note: the length method only returns the character count not the size of the StringBuffer - see capacity

StringBuffer sb = new StringBuffer("1234567890");

System.out.println("Reversed StringBuffer sb:" + sb.reverse());

StringBuffer sb1 = new StringBuffer("Hello World");
sb1.setLength(5);
System.out.prntln("sb1: " + sb1);     // displays Hello, it truncated the original

Note: setLength will truncate any characters if the capacity is less than the String contained inside it

StringBuffer sb = new StringBuffer("1234567890");

System.out.println("StringBuffer sb:" + sb.toString());

import java.util.StringTokenizer;

public class stringTokenizerTest {
   public static void main(String[] args) {

      String s = "This is the string to be tokenized by delimiting whitespaces";
      StringTokenizer tokens = new StringTokenerizer(s);

      System.out.println("There are " + tokens.countTokens() + " tokens" );

      System.out.println("The tokens are: ")
      while( tokens.hasMoreTokens() )
         System.out.println( tokens.nextToken() );
   }
}

String s = "This:is:the:string:to:be:tokenized:by:delimiting:whitespaces";
String delimiter = ":";
      
StringTokenizer tokens = new StringTokenerizer(s, delimiter);   // here we change the delimiter

x = Math.abs(99);       // returns 99
x = Math.abs(-99);      // returns the absolute value 99

Note: there are many overloaded methods that can take int, long, float, etc

x = Math.ceil(9.0);     // result is 9.0
x = Math.ceil(8.8);     // result is 9.0
x = Math.ceil(8.01);    // still rises to 9.0

Note: there is only one ceil method, ceil(double a)

x = Math.floor(9.0);     // result is 9.0
x = Math.floor(9.4);     // result is 9.0
x = Math.floor(9.99);    // still drops to 9.0

Note: there is only one ceil method, ceil(double a)

x = Math.max(1024, 1023);    // result is 1024

Note: there are many overloaded methods that can take int, long, float, etc

x = Math.min(1024, 1023);    // result is 1023

Note: there are many overloaded methods that can take int, long, float, etc

for ( int i = 1; i < 5; i++) {
   System.out.println( (int) (Math.random()*10) + " ");

Note: returns a random double number between 0.0 and 1.0