https://docs.oracle.com/javase/tutorial/java/data/strings.html

String Length

public class StringDemo {
	public static void main(String[] args) {
		String palindrome = "Dot saw I was Tod";
		
		// String Length
		int len = palindrome.length();
		
		char[] tempCharArray = new char[len];
		char[] charArray = new char[len];
		
		// Put original string in an array of chars
		for (int i = 0; i < len; i++) {
			tempCharArray[i] = palindrome.charAt(i);
		}
		
		for (int i = 0; i < len; i++) {
			System.out.println(tempCharArray[i]);
		}
		
		// Reverse array of chars
		for (int i = 0; i < len; i++) {
			charArray[i] = tempCharArray[len -1 -i];
		}
		
		String reversePalindrome = new String(charArray);
		System.out.println(reversePalindrome);
	}
}

getChar

The Java String class getChars() method copies the content of this string into a specified char array. There are four arguments passed in the getChars() method. The signature of the getChars() method is given below:

public void getChars(int srcBeginIndex, int srcEndIndex, char[] destination, int dstBeginIndex)

Concatenating Strings

The String class includes a method for concatenating two strings:

string1.concat(string2);

This returns a new string that is string1 with string2 added to it at the end.

You can also use the concat() method with string literals, as in:

"My name is ".concat("Rumplestiltskin");

Strings are more commonly concatenated with the + operator, as in

"Hello," + " world" + "!"

which results in

"Hello, world!"

The + operator is widely used in print statements. For example:

String string1 = "saw I was "; System.out.println("Dot " + string1 + "Tod");