Searching a character in the String
It looks through the record of indicated characters inside a given string. It begins looking from starting to the furthest limit of the string (from left to right) and returns the relating file whenever discovered in any case returns - 1.
Note: If the given string contains numerous events of a determined person then it returns a file of just the first event of indicated character.
Syntax:int indexOf(char c) // Accepts character as argument, Returns index of // the first occurrence of specified character
Syntax:
public int lastIndexOf(char c) // Accepts character as argument, Returns an // index of the last occurrence specified // character
Syntax:
public int IndexOf(char c, int indexFrom) char: character to be searched. indexfrom : an integer from where searching // Returns an index of specified character that // appeared at or after the specified index in // forward direction
Note: The returned list should be not exactly or equivalent to the predefined file.
Syntax:
public int lastIndexOf(char c, int fromIndex)
Syntax:
char charAt(int indexNumber)
// Java program to illustrate to find a character // in the string. import java.io.*; class GFG { public static void main (String[] args) { // This is a string in which a character // to be searched. String str = "GeeksforGeeks is a computer science portal"; // Returns index of first occurrence of character. int firstIndex = str.indexOf('s'); System.out.println("First occurrence of char 's'" + " is found at : " + firstIndex); // Returns index of last occurrence specified character. int lastIndex = str.lastIndexOf('s'); System.out.println("Last occurrence of char 's' is" + " found at : " + lastIndex); // Index of the first occurrence of specified char // after the specified index if found. int first_in = str.indexOf('s', 10); System.out.println("First occurrence of char 's'" + " after index 10 : " + first_in); int last_in = str.lastIndexOf('s', 20); System.out.println("Last occurrence of char 's'" + " after index 20 is : " + last_in); // gives ASCII value of character at location 20 int char_at = str.charAt(20); System.out.println("Character at location 20: " + char_at); // throws StringIndexOutOfBoundsException // char_at = str.charAt(50); } }
Output:
First occurrence of char 's' is found at : 4 Last occurrence of char 's' is found at : 28 First occurrence of char 's' after index 10 : 12 Last occurrence of char 's' after index 20 is : 15 Character at location 20: 111
Searching Substring in the String
// Java program to illustrate to find a substring // in the string. import java.io.*; class GFG { public static void main (String[] args) { // This is a string in which a substring // is to be searched. String str = "GeeksforGeeks is a computer science portal"; // Returns index of first occurrence of substring int firstIndex = str.indexOf("Geeks"); System.out.println("First occurrence of char Geeks"+ " is found at : " + firstIndex); // Returns index of last occurrence int lastIndex = str.lastIndexOf("Geeks"); System.out.println("Last occurrence of char Geeks is"+ " found at : " + lastIndex); // Index of the first occurrence // after the specified index if found. int first_in = str.indexOf("Geeks", 10); System.out.println("First occurrence of char Geeks"+ " after index 10 : " + first_in); int last_in = str.lastIndexOf("Geeks", 20); System.out.println("Last occurrence of char Geeks " + "after index 20 is : " + last_in); } }
Output:
First occurrence of char Geeks is found at : 0 Last occurrence of char Geeks is found at : 8 First occurrence of char Geeks after index 10 : -1 Last occurrence of char Geeks after index 20 is : 8
public boolean contains(CharSequence seq)
Note: CharSequence is an interface that is implemented by String class, Therefore we use string as an argument in contains() method.
// Java program to illustrate how to find a substring // in the string using contains import java.io.*; import java.lang.*; class GFG { public static void main (String[] args) { // This is a string in which substring // to be searched. String test = "software"; CharSequence seq = "soft"; boolean bool = test.contains(seq); System.out.println("Found soft?: " + bool); // it returns true substring if found. boolean seqFound = test.contains("war"); System.out.println("Found war? " + seqFound); // it returns true substring if found otherwise // return false. boolean sqFound = test.contains("wr"); System.out.println("Found wr?: " + sqFound); } }
Output:
Found soft?: true Found war? true Found wr?: false
Matching String Start and End
// Java program to illustrate to match // of start and end of a substring import java.io.*; class GFG { public static void main (String[] args) { // This is a string in which substring // is to be searched. String str = "GeeksforGeeks is a computer science portal"; System.out.println(str.startsWith("Geek")); System.out.println(str.startsWith("is", 14)); System.out.println(str.endsWith("port")); } }
Output:
true true false