Java Strings
Strings are used for storing text.
A String variable contains a collection of characters surrounded by double quotes (""):
Example
String greeting = "Hello";
String Length
A String in Java is actually an object, which means it contains methods that can perform certain operations on strings.
For example, you can find the length of a string with the length() method:
Example
String txt = "ABCDEFGHIJKLMNOPQRSTUVWXYZ";
System.out.println("The length of the txt string is: " + txt.length());
More String Methods
There are many string methods available in Java.
For example:
- The
toUpperCase()method converts a string to upper case letters. - The
toLowerCase()method converts a string to lower case letters.
Example
String txt = "Hello World";
System.out.println(txt.toUpperCase()); // Outputs "HELLO WORLD"
System.out.println(txt.toLowerCase()); // Outputs "hello world"
Finding a Character in a String
The indexOf() method returns the index (the position) of the first occurrence of a specified text in a string (including whitespace):
Example
String txt = "Please locate where 'locate' occurs!";
System.out.println(txt.indexOf("locate")); // Outputs 7
Note: Java counts positions from zero. 0 is the first position in a string, 1 is the second, 2 is the third ...
You can use the charAt() method to access a character at a specific position in a string:
Example
String txt = "Hello";
System.out.println(txt.charAt(0)); // H
System.out.println(txt.charAt(4)); // o
Comparing Strings
To compare two strings, you can use the equals() method:
Example
String txt1 = "Hello";
String txt2 = "Hello";
String txt3 = "Greetings";
String txt4 = "Great things";
System.out.println(txt1.equals(txt2)); // true
System.out.println(txt3.equals(txt4)); // false
Removing Whitespace
The trim() method removes whitespace from the beginning and the end of a string:
Example
String txt = " Hello World ";
System.out.println("Before: [" + txt + "]");
System.out.println("After: [" + txt.trim() + "]");
Complete String Reference
For a complete reference of String methods, go to our Java String Methods Reference.
The reference contains descriptions and examples of all string methods.
