In Java, startWith() method of the String class is present in java.lang package is used to check whether the string starts with a specific prefix. The package view is as follows:
--> java.lang Package
--> String Class
--> startWith() Method
Variants Of String startsWith() method
There are two variants of the startswith() method that are as follows:
- startsWith()
- startsWith(String prefix, int strt_pos)
1. String startsWith() method
This method tests if a string starts with the specified prefix beginning from the first index.
Syntax
public boolean startsWith(String prefix)
Parameters
The prefix to be matched.
Return Type
A boolean value that returns true if the character sequence represented by the argument is a prefix of the character sequence represented by this string else returns false.
Example:
Java
// Java Program to Illustrate startsWith() Method// of String class// Importing required classesimport java.util.*;// Classclass GFG { // Main driver method public static void main(String[] args) { // Creating custom string String str = new String( "Lazyroar is Computer Science Portal"); // Checking whether string starts with // corresponding input string passed // using startsWith() method and // later storing result in boolean value boolean ans1 = str.startsWith("Geeks"); boolean ans2 = str.startsWith("Computer"); // Printing the boolean value System.out.println(ans1); System.out.println(ans2); }} |
true false
2. String startsWith(String prefix, int strt_pos) method
This variant has two arguments and tests if a string starts with the specified prefix beginning a specified index. Here we are passing a starting position to be matched which allows us the flexibility
Syntax
public boolean startsWith(String prefix, int strt_pos)
Parameters:
- prefix: The prefix is to be matched.
- strt_pos: Start position where to begin looking in the string.
Return Type: A boolean value that returns true if the character sequence represented by the argument is a prefix of the character sequence represented by this string; false otherwise.
Example:
Java
// Java Program to Demonstrate Working of startsWith()// Method of String Class// Importing required classesimport java.lang.String;// Classpublic class GFG { // Main driver method public static void main(String args[]) { // Declaring and initialising custom string String Str = new String("Welcome to Lazyroar"); // Display message System.out.print( "Check whether string starts with Welcome at pos 11 : "); // Testing the prefix using startsWith() method System.out.println(Str.startsWith("Welcome", 11)); // Display message System.out.print( "Check whether string starts with geeks at pos 11 : "); // Testing the prefix using startsWith() method System.out.println(Str.startsWith("Geeks", 11)); }} |
Check whether string starts with Welcome at pos 11 : false Check whether string starts with geeks at pos 11 : true
Real-Life Example
Now let us look up possible applications seen in daily life. This method can primarily be useful to filter prefixes. For example: filtering phone numbers starting from a number of names starting from a particular letter. The latter one is explained in this article.
Example
Java
// Java Program to Illustrate startsWith() Method// As Real-time Scenario// Importing required classesimport java.util.*;// Classpublic class GFG { // Main driver method public static void main(String args[]) { // Declaring and initialising a string String Str = new String("Sandeep Jain"); // Testing the prefix using startsWith() method System.out.print( "Check Whether It Starts With Letter 'S' : "); // Printing corresponding boolean value System.out.println(Str.startsWith("S")); }} |
Check Whether It Starts With Letter 'S' : true
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