The java.lang Package

The String Class

In java String is implemented through String class.

Remember that any keyword starting with a capital letter is a class.

The String class is defined in the package ‘java.lang’, which is automatically imported in all java programs.
The ‘String’ class is declared as final, hence cannot be sub-classed.
The ‘String’ object represents a fixed length immutable character sequence.

String Constructors

• String()
• String(char arr[])
• String(char arr[],int startIndex,int numChars)
• String(String s)
• String(byte arr[])
• String(byte arr[], int startIndex, int numChars)

String s;   // way to make reference of String
 

1. String()

s = new String(); // creates an empty String


2.String(char str[])

char str[] = {'t','e','n','d','u','l','k','a','r'};
s = new String(str);   //s is referring to "tendulkar"

3. String(char arr[],int startIndex,int numChars)

s = new String (str, 2 , 3 );          // s is now referencing to "dul"

4. String(String s)            // - - - > copy constructor

s = new String("Vivek");               // invokes copy constructor, hence creates a new object

                                                v/s

s = "Vivek";          // does not invokes constructor. The String is created in String pool & its reference is assigned to s;

5. String(byte arr[])

byte arr[] = {118,105,118,101,107};
 

s = new String(arr);                       // s is referred to "vivek" 

5. String(byte arr[], int startIndex, int numChars)

s= new String(arr, 1 , 3 );      //  s refers to "vek"