String constructors in java

Hi!!! Welcome to flower brackets blog. In this post we are going to learn string constructors in java.

Also read – learn string literal in java

String constructors in java

Below are list of String class constructor with example,

String() :creates new empty string object.

String str = new String();

String(byte[] bytes) : constructs new string by decoding given array of bytes using platform default charset.

byte arr[] = {74, 97, 118, 97};
String str = new String(arr);
System.out.println(str); // Java

String(byte[] bytes, Charset charset) : constructs new string by decoding given array of bytes using specified charset.

byte arr[] = {74, 97, 118, 97};
Charset ch = Charset.defaultCharset();
String str = new String(arr, ch);
System.out.println(str); // Java

String(byte[] bytes, int offset, int length) : constructs new string by decoding given subarray of bytes using platform’s default charset.

byte bytes[] = {76,77,78,79,80,81,82};
String str = new String(bytes,1,4);
System.out.println(str); // MNOP

String(byte[] bytes, int offset, int length, Charset charset) : constructs new string by decoding given subarray of bytes using specified charset.

byte arr[] = { 'h', 'e', 'l', 'l', 'o' };
String str = new String(arr, 1, 3);
System.out.println(str); // ell

String(byte[] bytes, int offset, int length, String charsetName) : constructs new string by decoding given subarray of bytes using specified charset.

byte arr[] = { 'h', 'e', 'l', 'l', 'o' };
try
{
String str = new String(arr, 1, 3, "UTF-8");
System.out.println(str); // ell
}
catch(UnsupportedEncodingException ex)
{
ex.printStackTrace();
}

String(byte[] bytes, String charsetName) : Constructs new string by decoding specified array of bytes using the specified charset.

byte arr[] = {'h', 'e', 'l', 'l', 'o'};
String str = new String(arr);
System.out.println(str); // hello

String(char[] value) : here it allocates a new String so that it represents the sequence of characters currently contained in the character array argument.

char ch[] = {'H', 'e', 'l', 'l', 'o'};
String str = new String(ch);
System.out.println(str); // Hello

String(char[] value, int offset, int count) : this allocates a new String that contains characters from a subarray of the character array argument.

char[] ch1 = new char[] { 'j', 'a', 'v', 'a' };
String s1 = String.valueOf(ch1, 2, 2);
char[] ch2 = new char[] { '8', '2', '3' };
String s2 = String.valueOf(ch2, 1, 2);
System.out.println(s1); // va
System.out.println(s2); // 23

String(int[] codePoints, int offset, int count) : this allocates a new String that contains characters from a subarray of the Unicode code point array argument.

int arr[] = new int[26];
int num = 97;
for(int a = 0; a < 26; a++)
{
arr[a] = num + a;
}
String str = new String(arr, 0, 26);
System.out.println(str); // abcdefghijklmnopqrstuvwxyz

String(String original) : this initializes a newly created String object so that it represents the same sequence of characters as the argument; in other words, the newly created string is a copy of the argument string.

In Strings, null values are not allowed. For more on this constructor click here.

String(StringBuffer buffer) : this allocates a new string that contains the sequence of characters currently contained in the string buffer argument.

StringBuffer sb = new StringBuffer("Hello");
String str = new String(sb);
System.out.println(str); // Hello

String(StringBuilder builder) : this allocates a new string that contains the sequence of characters currently contained in the string builder argument.

StringBuilder sb = new StringBuilder("Hello");
String str = new String(sb);
System.out.println(str); // Hello

Also read – learn string and its methods

Reference – oracle docs.

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