# String methods in Java

package com.example.demo;

import org.springframework.boot.SpringApplication;
import org.springframework.boot.autoconfigure.SpringBootApplication;

import java.util.Arrays;

@SpringBootApplication
public class Demo1Application {

	public static void main(String[] args) throws InterruptedException {
		SpringApplication.run(Demo1Application.class, args);

        String str1 = " Hello word ! ";
		String str2 = "Hello";
		String str3 = new String("Hello");

		System.out.println("----------------------------------");
		System.out.println("str1="+str1);
		System.out.println("str2="+str2);
		System.out.println("str3="+str3);
		System.out.println("----------------------------------");

		//length()
		System.out.println("str1.length()="+str1.length());

		//toUpperCase()
		System.out.println("str1.toUpperCase()="+str1.toUpperCase());

		//toLowerCase()
		System.out.println("str1.toLowerCase()="+str1.toLowerCase());

		//trim()
		System.out.println("str1.trim()="+str1.trim());

		//toCharArray()
		char[] charArray = str2.toCharArray();
		System.out.println("charArray.length="+charArray.length);

		//substring()
		System.out.println("str2.substring(0,2)="+str2.substring(0,2));
		System.out.println("str2.substring(2)="+str2.substring(2));

		//replace()
		System.out.println("str2.replace(\"l\",\"3\")"+str2.replace("l","3"));

		//replaceFirst()
		System.out.println("str2.replaceFirst(\"l\",\"3\")="+str2.replaceFirst("l","3"));

		//startsWith() & endsWith()
		System.out.println("str2.startsWith(\"H\")="+str2.startsWith("H"));

		//charAt()
		System.out.println("str2.charAt(2)="+str2.charAt(2));

		//indexOf() & lastIndexOf()
		System.out.println("str2.indexOf(\"l\")="+str2.indexOf("l"));
		System.out.println("str2.lastIndexOf(\"l\")="+str2.lastIndexOf("l"));

		//equals() & equalsIgnoreCase()
		System.out.println("str2.equals(str3)="+str2.equals(str3));

		// "==" operator
		System.out.println("str2 == str3 // returns "+str2 == str3);

		//compareTo()
		System.out.println("str2.compareTo(str3)="+str2.compareTo(str3));

		//String.valueOf() => create a String
		System.out.println("valueOf(4)="+String.valueOf(4));

		//String.join()
		System.out.println("String.join(\"-\", \"abc\", \"dcf\", \"nnn\")="+String.join("-", "abc", "dcf", "nnn"));

		// chars() - returns an IntStream of char values of the given string
		// codePoints() - returns an IntStream of Unicode code points of the chars of the given string
		str2.chars().forEach(System.out::println);

		//split()
		Arrays.stream(str1.split(" ")).forEach( var1 -> {
			 System.out.println("var1="+var1);
		});
		
		//Java 11
		//isBlank()
		System.out.println("\n \n".isBlank());

		//Java 11
		//lines() & count()
		System.out.println("\n\n".lines().count());

		//Java 11
		//repeat()
		System.out.println("a".repeat(3));

		//Java 12
		//transform()
		var strX = str2.transform(str -> str.concat(" John"))
				              .transform(String::toUpperCase);
		System.out.println("strX= "+strX);

		//Java 15
		//formatted()
		String strF = "1) %s, 2) %s";
		System.out.println("strF.formatted() = "+strF.formatted("John", "Emma"));
	}
}

----------------------------------
str1= Hello word ! 
str2=Hello
str3=Hello
----------------------------------
str1.length()=14
str1.toUpperCase()= HELLO WORD ! 
str1.toLowerCase()= hello word ! 
str1.trim()=Hello word !
charArray.length=5
str2.substring(0,2)=He
str2.substring(2)=llo
str2.replace("l","3")He33o
str2.replaceFirst("l","3")=He3lo
str2.startsWith("H")=true
str2.charAt(2)=l
str2.indexOf("l")=2
str2.lastIndexOf("l")=3
str2.equals(str3)=true
false
str2.compareTo(str3)=0
valueOf(4)=4
String.join("-", "abc", "dcf", "nnn")=abc-dcf-nnn
72
101
108
108
111
var1=
var1=Hello
var1=word
var1=!
true
2
aaa
strX= HELLO JOHN
strF.formatted() = 1) John, 2) Emma