Strings

String string = "Everything inside these (besides escape sequences and quotes) will be allowed in a string"
 

Methods

String myString = "I love MELONS";
 
int length = myString.length(); // Gets length
char firstChar = myString.charAt(0); // Indexes start at 0. You are not allowed to use this
 
int index = myString.indexOf("l"); // Gets index of first instance of a string. if there's none, it will give "-1"
int index2 = myString.indexOf("love"); // Also possible; would be the same as the index above.
 
String sub = myString.substring(0, 2); // Will get the character at index 0 up to the index before 2. Its range is basically [0, 2)
String sub2 = myString.substring(3) // Will return everything after and including index 3; [3,∞)
 
String upper = myString.toUpperCase(); // Makes things upper case
String lower = myString.toLowerCase();
 
String[] split = myString.split(" "); // Returns an array of strings for each word.

You can ONLY use these methods for strings:

• length()
• substring()
• indexOf()
• toUpperCase()
• toLowerCase()
• split();

In some contexts you can also use:

• charAt()

Reading strings as input

Scanner input = new Scanner(System.in);
input.next();

Comparing strings

// You cannot use double-equal signs. it will not work
String temp = "My string";
if (temp.equals("My string")) {
	// Will run this block because every character is the same
}

compareTo()

Find the difference of the characters between the two strings. I.e. the difference between A and B is -1 as B is larger.

String s1 = "Apple", s2 = "Boy";
// The method "compareTo" compares every character's ASCII value
if (s1.compareTo(s2) == 0) {
	// S1 has the same ASCII characters as s2
}
if (s1.compareTo(s2) < 0) { // it returns a random negative value
	// s1 comes earlier alphabetically than s2.
	// "A" is index 65 and "B" is index 66. Since 65 < 66, the function returns a value less than 0
}
if (s2.compareTo(s1) > 0) {
	// s2 comes earlier alphabetically than s1.
}

ASCII

char x = 'a' // this i show you dec;are character
int a1 = x; // Will turn the character into its ASCII value
 
char newChar = (char) (x + 7) // You can cast an integer into a character via the ASCII value
 
int asciiValue = (int) x // this explicitly shows how the character is casted into a number to get its ascii value!

Concatenation

String str = "";
 
str += "Here's some content";