String Methods in Java

Extracting a Substring from a String

slice() method is used to extract a part or substring from a string. This method takes 2 parameters: like str.slice(startIndex, endIndex).

Example

var str = “The Best IT Company in Ludhiana is ershairykalra.”;

var subStr = str.slice(4, 19);

document.write(subStr);

Extracting a Fixed Number of Characters from a String

JavaScript also provide the substr() method which is similar to slice() with a small difference, the second parameter specifies the number of characters to extract instead of ending index, like str.substr(startIndex, length). If length is 0 or a negative number, an empty string is returned. The following example demonstrates how it works:

Example

var str = ” The Best IT Company in Ludhiana is ershairykalra.”;

document.write(str.substr(4, 15));

Replacing the Contents of a String

Replace() method is used to replace part of a string with another string and returns a new string. This method takes two parameters like str.replace(regexp|substr, newSubstr).

• First is regular expression to match or substring to be replaced
• Second is a replacement string

Example

var str = ” The Best IT Company in Ludhiana is ershairykalra company.”;

var result = str.replace(“Company”, “Institute”);

alert(result);

Replace() method is case sensitive and pick first string only; for case-insensitive we use a regular expression (regexp) with an i modifier

var str = ” The Best IT Company in Ludhiana is ershairykalra company.”;

var result = str.replace(/company /i, ” Institute “);

alert(result);

if we want to replace all string in a case-insensitive manner you can use the g modifier along with the i modifier, like this:

Example

var str = ” The Best IT Company in Ludhiana is ershairykalra company.”;

var result = str.replace(/company /ig, ” Institute “);

alert(result);

Converting a String to Uppercase or Lowercase

toUpperCase() and  toLowerCase methods are used to convert a string to uppercase and lowercase

Example

var str = “Shairy Kalra”;

var result = str.toUpperCase();

document.write(result);

var result = str.toLowerCase();

document.write(result);

Accessing Individual Characters from a String

charAt() method is used to access individual character from a string, like str.charAt(index).

Example

var str = “Shairy Kalra”;

document.write(str.charAt(6));