Java Strings

The String is probably the most commonly used class in Java's class library. The reason for this is that strings are a very important part of programming.

The first thing to understand about strings is that every string you create is actually an object of the type String. Even string constants are actually the String objects. For example, in the following statement

System.out.println("This is a String");

the string "This is a String" is a String object.

The second thing to understand about strings is that objects of the type String are immutable, once a String object is created, its contents cannot be altered. While this may seem like a serious restriction, it is not, for the following two reasons :

1. If you need to change a string, you can always create a new one that contains the modifications.
2. Java defines peer classes of String, called the StringBuffer and the StringBuilder, which allow strings to be altered, so all of the normal string manipulations are string available in Java.

Create Strings in Java

In Java, String can be constructed in a variety of ways. The easiest way is to use a statement like this :

String myStr = "this is a string";

Once you have created a String object, you can use it anywhere that a string is allowed. For example, the following statement displays myStr :

System.out.println(myStr);

Java defines one operator for the String objects: +. It is used to concatenate two strings. For example, the following statement

String myStr = "I" + " like " + "Java";

results in myStr containing "I like Java"

Java Strings Example

The following Java program demonstrates the preceding concepts of Strings :

/* Java Program Example - Java Strings Class
 * This program demonstrates the Strings  */
 
 class JavaProgram
 {
     public static void main(String args[])
     {
    
         String strObj1 = "First String";
         String strObj2 = "Second String";
         String strObj3 = strObj1 + " and " + strObj2;
         
         /* now print the values of all the String objects */
         System.out.println(strObj1);
         System.out.println(strObj2);
         System.out.println(strObj3);
       
     }
 }

When the above Java program is compile and executed, it will produce the following output:

Java Online Test