In this guide, we will discuss the Java StringBuilder indexOf() method with the help of examples.
The syntax of indexOf() method is:
sb.indexOf("hello"); //searches string "hello" in the sb
sb.indexOf("hello", 4) //starts searching string "hello" from index 4
Here, sb is an object of StringBuilder class.
indexOf() Description
There are two variations of indexOf() method in Java StringBuilder class.
public int indexOf(String str): It returns the index of first occurrence of the string str in the StringBuilder instance.
public int indexOf(String str, int fromIndex): It starts the search from the specified index fromIndex and returns the index of string str.
indexOf() Parameters
The indexOf() method of Java StringBuilder class takes a single parameter:
- str: The String str represents the character sequence that needs to be searched in the StringBuilder instance
sb. - fromIndex: Represents an index from where the search starts.
indexOf() Return Value
- It returns an integer value that represents the index of the first occurrence of specified string. If the specified string is not found then this method returns -1.
Example 1: Specified String without fromIndex
public class JavaExample {
public static void main(String[] args) {
StringBuilder sb = new StringBuilder("Cool Book");
System.out.println("Given String: " + sb);
// first occurrence of string "oo"
System.out.println("Index of string 'oo': "+sb.indexOf("oo"));
}
}
Output:
Example 2: Searching string from a specified index
public class JavaExample {
public static void main(String[] args) {
StringBuilder sb = new StringBuilder("Cool Book");
System.out.println("Given String: " + sb);
// Search string "oo" starting from index 3
System.out.println("Occurrence of 'oo' after index 3 is: "+
sb.indexOf("oo", 3));
}
}
Output:
Example 3: When specified string is not found
public class JavaExample {
public static void main(String[] args) {
StringBuilder sb = new StringBuilder("Cool Book");
System.out.println("Given String: " + sb);
// Index of string "Beginners" in the given string
System.out.println("Index of 'Beginners' is: "+
sb.indexOf("Beginners"));
}
}
Output:
Example 4: String doesn’t exist after specified index
public class JavaExample {
public static void main(String[] args) {
StringBuilder sb = new StringBuilder("Cool Book");
System.out.println("Given String: " + sb);
// Index of string "oo" after index 10
System.out.println("Index of 'oo' after 10: "+sb.indexOf("oo",10));
}
}
Output:
