Java: String startsWith() method

In this article, we will check or test whether string starts with specified prefix or NOT using String’s startsWith() method

 

startsWith() method:

  • This String method test whether invoking string starts with specified prefix or NOT

Note:

  • there are 2 variants or overloaded startsWith() methods
  • 1st variant checks over complete range of string i.e.; starting from 0th index-position
  • Whereas 2nd variant test from specified offset (or specified index-position)

Method Signature:

public boolean startsWith(String prefix);

public boolean startsWith(String prefix, int toffset);

Parameters:

  • prefix –> substring that need to be searched from invoking-string
  • toffset –> this is applicable only for 2nd variant to specify from where to start searching specified-prefix (basically starting index-position)

Returns:

startsWith() method

Returns

public boolean startsWith(String prefix); Returns boolean true, if the invoking-string starts with specified-prefix

Otherwise, returns false;

public boolean startsWith(String prefix, int toffset); Returns boolean true, if the invoking-string starts with specified-prefix starting from specified-offset

Otherwise, returns false;

 

 

Examples on startWith() method:

Example 1: Java program to test whether invoking string starts with specified prefix

Method Signature:

public boolean startsWith(String prefix);

StringStartsWithMethod.java

package in.bench.resources.string.methods;

public class StringStartsWithMethod {

	public static void main(String[] args) {

		// Example 1: tests whether str starts with "Java"
		String testStr1 = "Java is a super cool language";
		boolean bStr1 = testStr1.startsWith("Java");
		System.out.println("Whether \"" + testStr1 
				+ "\" starts with 'Java' : " + bStr1);

		// Example 2: tests whether str starts with "Bench"
		String testStr2 = "BenchResources.Net is a Java weblog";
		boolean bStr2 = testStr2.startsWith("Bench");
		System.out.println("\nWhether \"" + testStr2 
				+ "\" starts with 'Bench' : " + bStr2);

		// Example 3: tests whether str starts with "class"
		String testStr3 = "String class has useful methods";
		boolean bStr3 = testStr2.startsWith("class");
		System.out.println("\nWhether \"" + testStr3 
				+ "\" starts with 'class' : " + bStr3);

		// Example 4: tests whether str starts with "Oscar"
		String testStr4 = "Oscar is a highest award in films";
		boolean bStr4 = testStr4.startsWith("Oscar");
		System.out.println("\nWhether \"" + testStr4 
				+ "\" starts with 'Oscar' : " + bStr4);

		// Example 5: tests whether str starts with "Grammy"
		String testStr5 = "Grammy award is considered equivalent";
		boolean bStr5 = testStr5.startsWith("award");
		System.out.println("\nWhether \"" + testStr5 
				+ "\" starts with 'award' : " + bStr5);
	}
}

Output:

Whether "Java is a super cool language" 
						starts with 'Java' : true

Whether "BenchResources.Net is a Java weblog" 
						starts with 'Bench' : true

Whether "String class has useful methods" 
						starts with 'class' : false

Whether "Oscar is a highest award in films" 
						starts with 'Oscar' : true

Whether "Grammy award is considered equivalent" 
						starts with 'award' : false

 

Example 2: Java program to test whether invoking string starts with specified prefix starting from specified offset

Method Signature:

public boolean startsWith(String prefix, int toffset);

StringStartsWithMethod2.java

package in.bench.resources.string.methods;

public class StringStartsWithMethod2 {

	public static void main(String[] args) {

		// Example 1: tests whether str starts with "super" 
		// starting from 10th index-position
		String testStr1 = "Java is a super cool language";
		boolean bStr1 = testStr1.startsWith("super", 10);
		System.out.println("Whether \"" + testStr1 
				+ "\" starts with 'super' starting "
				+ "from 10th index-position : " + bStr1);

		// Example 2: tests whether str starts with "Net" 
		// starting from 15th index-position
		String testStr2 = "BenchResources.Net is a Java weblog";
		boolean bStr2 = testStr2.startsWith("Net", 15);
		System.out.println("\nWhether \"" + testStr2 
				+ "\" starts with 'Net' starting "
				+ "from 15th index-position : " + bStr2);

		// Example 3: tests whether str starts with "class" 
		// starting from 5th index-position
		String testStr3 = "String class has useful methods";
		boolean bStr3 = testStr2.startsWith("class", 5);
		System.out.println("\nWhether \"" + testStr3 
				+ "\" starts with 'class' starting "
				+ "from 5th index-position : " + bStr3);

		// Example 4: tests whether str starts with "Oscar" 
		// starting from 19th index-position
		String testStr4 = "Oscar is a highest award in films";
		boolean bStr4 = testStr4.startsWith("award", 19);
		System.out.println("\nWhether \"" + testStr4 
				+ "\" starts with 'award' starting "
				+ "from 19th index-position : " + bStr4);

		// Example 5: tests whether str starts with "Grammy" 
		// starting from 0th index-position
		String testStr5 = "Grammy award is considered equivalent";
		boolean bStr5 = testStr5.startsWith("award", 0);
		System.out.println("\nWhether \"" + testStr5 
				+ "\" starts with 'award' starting "
				+ "from 0th index-position : " + bStr5);
	}
}

Output:

Whether "Java is a super cool language" 
	starts with 'super' starting from 10th index-position : true

Whether "BenchResources.Net is a Java weblog" 
	starts with 'Net' starting from 15th index-position : true

Whether "String class has useful methods" 
	starts with 'class' starting from 5th index-position : false

Whether "Oscar is a highest award in films" 
	starts with 'award' starting from 19th index-position : true

Whether "Grammy award is considered equivalent" 
	starts with 'award' starting from 0th index-position : false

 

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References:

 

Happy Coding !!
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