String Class in Java (Part 1)

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The String Class: (Part 1)

• The String class is under Lang package in Java. But as this package is by-default imported in Java, there is not need to write the import statement to use String in your program.
• The char type represents only one character. To represent a string of characters, we can use the data type called String. For example, the following code declares message to be a string with the value "Welcome to Java".

String message = "Welcome to Java";

• A String object is immutable: Its content cannot be changed once the string is created.

Creating Strings:

• A String is combination of one or more characters. There are three methods to create Strings:
  1. By creating object of String class:
     • Syntax:
       String object_name = new String(“any_string”);
     • For example:
       String name = new String(“Mr. Harvey Specter”);
  2. By creating a String variable or literal:
     • Syntax:
       String var_name = “Value”;
     • For example:
       String name = “Mr. Mike Ross”;
  3. From character array:
     • Syntax:
       String name = new String(Name_Of_Char_Array);
     • For example:
       char value[] = {‘a’, ‘b’, ‘c’, ‘d’, ‘e’};
       String name = new String(value);

Simple Methods of String class:

• Example: (Length)

  	class test {
  	public static void main(String ar[]) {
  	String str = "Welcome to Java!";
  	System.out.println(str.length()); // prints 16 (space included)
  	}
  	}

  view raw pattern.java hosted with ❤ by GitHub
• Example: (charAt - Part 1)

  	class test {
  	public static void main(String ar[]) {
  	String str = "Welcome to Java!";
  	System.out.println(str.charAt(3)); // prints c
  	}
  	}

  view raw pattern.java hosted with ❤ by GitHub
• Example: (charAt - Part 2)

  	class test {
  	public static void main(String ar[]) {
  	String str = "Welcome to Java!";
  	for(int i=0;i<str.length();i++)
  	{
  	System.out.println(str.charAt(i)); // prints all the characters in the string
  	}
  	}
  	}

  view raw pattern.java hosted with ❤ by GitHub
• Example: (concat)

  	class test {
  	public static void main(String ar[]) {
  	String str1 = "Welcome to Java ";
  	String str2 = "world!";
  	String str3 = str1.concat(str2); // prints Welcome to Java world!
  	System.out.println(str3);
  	String str4 = str2.concat(str1);
  	System.out.println(str4); // world!Welcome to Java
  	}
  	} // spot the diff between str3 and str4

  view raw pattern.java hosted with ❤ by GitHub
• Example: (toUpperCase)

  	class test {
  	public static void main(String ar[]) {
  	String str1 = "Welcome to Java ";
  	String str2 = str1.toUpperCase();
  	System.out.println("Original: "+ str1); // prints Original: Welcome to Java
  	System.out.println("New: "+ str2);// prints New: WELCOME TO JAVA
  	}
  	}

  view raw pattern.java hosted with ❤ by GitHub
• Example: (toLowerCase) (Opposite to toUpperCase())
• Example: (trim)

  	class test {
  	public static void main(String ar[]) {
  	String str1 = " Welcome to Java ";
  	String str2 = str1.trim();
  	System.out.println("Original:"+ str1);// prints Original: Welcome to Java
  	System.out.println("After trim:"+ str2);// prints After trim:Welcome to Java
  	}
  	}

  view raw pattern.java hosted with ❤ by GitHub

Click HERE for the Comparison Methods of String class.