The method indexOf() returns the first occurrence index of a character or a String in another String. We can pass the index of the character to start searching from.
Note that the method returns -1 if the passed value is not found.
Available Signatures
public int indexOf(int ch)
public int indexOf(int ch, int fromIndex)
public int indexOf(String str)
public int indexOf(String str, int fromIndex)
Example
@Test
public void whenCallIndexOf_thenCorrect() {
String str = "foo";
assertEquals(1, str.indexOf("o"));
assertEquals(-1, str.indexOf("s"));
}