- Java Basic
- Java Object Oriented
- Java Advanced
- Java Strings
Strings which are widely used in Java programming, are a sequence of characters. In the Java programming language, strings are objects. The Java platform provides the String class to create and manipulate strings.
Example
Whenever it encounters a string literal in your code, the compiler creates a String object with its value in this case, "Hello world!'.
As with any other object, you can create String objects by using the new keyword and a constructor. The String class has eleven constructors that allow you to provide the initial value of the string using different sources, such as an array of characters:
Example
Output
Note:The String class is immutable, so that once it is created a String object cannot be changed. If there is a necessity to make alot of modifications to Strings of characters then you should use String Buffer & String Builder Classes.
String Length:
Methods used to obtain information about an object are known as accessor methods. One accessor method that you can use with strings is the length() method, which returns the number of characters contained in the string object.
After the following two lines of code have been executed, len equals 17:
Output
Concatenating Strings
The String class includes a method for concatenating two strings:
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:
Strings are more commonly concatenated with the + operator, as in:
which results in
Example
Output
Creating Format Strings
You have printf() and format() methods to print output with formatted numbers. The String class has an equivalent class method, format(), that returns a String object rather than a PrintStream object. Using String's static format() method allows you to create a formatted string that you can reuse, as opposed to a one-time print statement. For example, instead of:
you can write:
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