In this article, we will discuss StringBuffer’s indexOf() method which returns first occurrence of specified sub-string
1. StringBuffer’s indexOf() method:
- This method is used to get first occurrence of specified sub-string i.e.; index-position
- Note: There are 2 variants or overloaded indexOf() methods
1.1 Method Signature:
public int indexOf(String str);
public int indexOf(String str, int fromIndex);
1.2 Parameters:
- str –> sub-string to be searched, to get its 1st occurrence
- fromIndex –> starting position from where search should begin
1.3 Returns:
| indexOf() method |
Returns |
| indexOf(String str); | Returns 1st occurrence of specified sub-string (i.e.; index-position for 1st occurrence) |
| indexOf(String str, int fromIndex); | Returns 1st occurrence of specified sub-string starting from specified index (i.e.; index-position for 1st occurrence) |
1.4 Throws:
- NullPointerException, if specified sub-string is null
2. Examples on indexOf() method:
2.1 To find 1st occurrence of specified sub-string
- Below illustration depicts how to get 1st occurrence of specified sub-string
Method signature:
public int indexOf(String str);
StringBufferIndexOfMethod.java
package in.bench.resources.stringbuffer.methods;
public class StringBufferIndexOfMethod {
public static void main(String[] args) {
// StringBuffer
StringBuffer sb = new StringBuffer("BenchResource.Net");
// 1. To get index of substring 'Resource'
int indexOfSubstring1 = sb.indexOf("Resource");
// print to console
System.out.println("1. Index of substring 'Resource' is : "
+ indexOfSubstring1);
// 2. To get index of substring 'Net'
int indexOfSubstring2 = sb.indexOf("Net");
// print to console
System.out.println("2. Index of substring 'Net' is : "
+ indexOfSubstring2);
}
}
Output:
1. Index of substring 'Resource' is : 5
2. Index of substring 'Net' is : 14
2.2 To find 1st occurrence of specified sub-string starting from specified index
- Below illustration depicts how to get 1st occurrence of specified sub-string starting from specified index-position as 2nd argument
Method signature:
public int indexOf(String str, int fromIndex);
StringBufferIndexOfMethod2.java
package in.bench.resources.stringbuffer.methods;
public class StringBufferIndexOfMethod2 {
public static void main(String[] args) {
// StringBuffer
StringBuffer sb = new StringBuffer("BenchResource.Net");
// 1. To get index of substring 'sour',
// starting from 6th index
int indexOfSubstringfrom1 = sb.indexOf("sour", 6);
// print to console
System.out.println("1. Index of substring 'sour', "
+ "starting from 6th position is : "
+ indexOfSubstringfrom1);
// 2. To get index of substring 'Net',
// starting from 10th index
int indexOfSubstringfrom2 = sb.indexOf("Net", 10);
// print to console
System.out.println("2. Index of substring 'Net', "
+ "starting from 10th position is : "
+ indexOfSubstringfrom2);
}
}
Output:
1. Index of substring 'sour', starting from 6th position is : 7
2. Index of substring 'Net', starting from 10th position is : 14
Related Articles:
- Java – StringBuffer class
- Java – StringBuffer append() method (13)
- Java – StringBuffer capacity() method
- Java – StringBuffer charAt(int index) method
- Java – StringBuffer delete(int start, int end) method
- Java – StringBuffer deleteCharAt(int index) method
- Java – StringBuffer ensureCapacity(int minimumCapacity) method
- Java – StringBuffer indexOf() method (2)
- Java – StringBuffer insert() method (12)
- Java – StringBuffer lastIndexOf() method (2)
- Java – StringBuffer length() method
- Java – StringBuffer replace(int start, int end, String str) method
- Java – StringBuffer reverse() method
- Java – StringBuffer substring(int start, int end) method
References:
- https://docs.oracle.com/javase/tutorial/essential/concurrency/immutable.html
- https://docs.oracle.com/javase/tutorial/essential/concurrency/imstrat.html
- https://docs.oracle.com/javase/tutorial/java/data/strings.html
- https://docs.oracle.com/javase/8/docs/api/java/lang/String.html
- https://docs.oracle.com/javase/8/docs/api/java/lang/class-use/String.html
- https://docs.oracle.com/javase/8/docs/api/java/lang/StringBuffer.html
- https://docs.oracle.com/javase/8/docs/api/java/lang/StringBuilder.html
Happy Coding !!
Happy Learning !!
