Finding word in string java

Looking back at the original question, we need to find some given keywords in a given sentence, count the number of occurrences and know something about where. I don’t quite understand what «where» means (is it an index in the sentence?), so I’ll pass that one… I’m still learning java, one step at a time, so I’ll see to that one in due time

It must be noticed that common sentences (as the one in the original question) can have repeated keywords, therefore the search cannot just ask if a given keyword «exists or not» and count it as 1 if it does exist. There can be more then one of the same. For example:

// Base sentence (added punctuation, to make it more interesting):
String sentence = "Say that 123 of us will come by and meet you, "
                + "say, at the woods of 123woods.";

// Split it (punctuation taken in consideration, as well):
java.util.List<String> strings = 
                       java.util.Arrays.asList(sentence.split(" |,|\."));

// My keywords:
java.util.ArrayList<String> keywords = new java.util.ArrayList<>();
keywords.add("123woods");
keywords.add("come");
keywords.add("you");
keywords.add("say");

By looking at it, the expected result would be 5 for «Say» + «come» + «you» + «say» + «123woods», counting «say» twice if we go lowercase. If we don’t, then the count should be 4, «Say» being excluded and «say» included. Fine. My suggestion is:

// Set... ready...?
int counter = 0;

// Go!
for(String s : strings)
{
    // Asking if the sentence exists in the keywords, not the other
    // around, to find repeated keywords in the sentence.
    Boolean found = keywords.contains(s.toLowerCase());
    if(found)
    {
        counter ++;
        System.out.println("Found: " + s);
    }
}

// Statistics:
if (counter > 0)
{
    System.out.println("In sentence: " + sentence + "n"
                     + "Count: " + counter);
}

And the results are:

Found: Say
Found: come
Found: you
Found: say
Found: 123woods
In sentence: Say that 123 of us will come by and meet you, say, at the woods of 123woods.
Count: 5

Strings are a very important aspect from a programming perspective as many questions can be framed out among strings. There arise wide varied sets of concepts and questions that are pivotal to understanding strings. Now over here will be discussing different ways to play with strings where we will be playing with characters with strings and substrings which is a part of input strings with help of inbuilt methods and also by proposing logic listing wide varied ways as follows: 

Searching a Character in the String

Way 1: indexOf(char c)

It searches the index of specified characters within a given string. It starts searching from the beginning to the end of the string (from left to right) and returns the corresponding index if found otherwise returns -1. 

Note: If the given string contains multiple occurrences of a specified character then it returns the index of the only first occurrence of the specified character. 

Syntax: 

int indexOf(char c)
// Accepts character as argument, Returns index of 
// the first occurrence of specified character 

Way 2: lastIndexOf(char c)

It starts searching backward from the end of the string and returns the index of specified characters whenever it is encountered. 

Syntax: 

public int lastIndexOf(char c)
// Accepts character as argument, Returns an 
// index of the last occurrence specified 
// character

Way 3: indexOf(char c, int indexFrom)

It starts searching forward from the specified index in the string and returns the corresponding index when the specified character is encountered otherwise returns -1. 

Note: The returned index must be greater than or equal to the specified index. 

Syntax: 

public int IndexOf(char c, int indexFrom)

Parameters: 

• The character to be searched
• An integer from where searching

Return Type: An index of a specified character that appeared at or after the specified index in a forwarding direction.

Way 4: lastIndexOf(char c, int fromIndex)

It starts searching backward from the specified index in the string. And returns the corresponding index when the specified character is encountered otherwise returns -1. 

Note: The returned index must be less than or equal to the specified index. 

Syntax: 

public int lastIndexOf(char c, int fromIndex)

Way 5: charAt(int indexNumber)

Returns the character existing at the specified index, indexNumber in the given string. If the specified index number does not exist in the string, the method throws an unchecked exception, StringIndexOutOfBoundsException. 

Syntax:

char charAt(int indexNumber)

Example:

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

 Way 6: Searching Substring in the String

The methods used for searching a character in the string which are mentioned above can also be used for searching the substring in the string. 

Example

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

Way 7: contains(CharSequence seq): It returns true if the string contains the specified sequence of char values otherwise returns false. Its parameters specify the sequence of characters to be searched and throw NullPointerException if seq is null. 

Syntax: 

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. 

Example 

Found soft?: true
Found war? true
Found wr?: false

 Way 8: Matching String Start and End 

• boolean startsWith(String str): Returns true if the string str exists at the starting of the given string, else false.
• boolean startsWith(String str, int indexNum): Returns true if the string str exists at the starting of the index indexNum in the given string, else false.
• boolean endsWith(String str): Returns true if the string str exists at the ending of the given string, else false.

Example:

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Problem Description

How to search a word inside a string?

Solution

This example shows how we can search a word within a String object using indexOf() method which returns a position index of a word within the string if found. Otherwise it returns -1.

public class SearchStringEmp{
   public static void main(String[] args) {
      String strOrig = "Hello readers";
      int intIndex = strOrig.indexOf("Hello");
      
      if(intIndex == - 1) {
         System.out.println("Hello not found");
      } else {
         System.out.println("Found Hello at index " + intIndex);
      }
   }
}

Result

The above code sample will produce the following result.

Found Hello at index 0

This example shows how we can search a word within a String object

public class HelloWorld {
   public static void main(String[] args) {
      String text = "The cat is on the table";
      System.out.print(text.contains("the"));
   }
}

Result

The above code sample will produce the following result.

true

java_strings.htm

Java Program to Search Word in a String

In java programming, indexOf method is used to find the index of sub string in the string.

indexOf method returns index if sub string is found in the string, otherwise returns -1.

This java program is used to check whether word or substring is found in the string or not.

Here string and word are both user inputs.

indexOf method is used to search the word in string from left to right.

import java.util.Scanner;

public class SearchString {
	public static void main(String[] args){
		Scanner sc=new Scanner(System.in);
		System.out.println("Search word in string"); 
		System.out.println("-----------------------"); 
		System.out.print("Enter String: "); 
		String str = sc.nextLine();
		System.out.print("Enter word to search: ");
		String word =sc.next();
		
		int index = str.indexOf(word); 
		if(index >= 0){
			System.out.print("Search Found index: ");
			System.out.println(index);
		} else {
			System.out.println("No Search Found!");
		}	
	}
}

Output:

D:Java_Programs>javac SearchString.java
D:Java_Programs>java SearchString 
Search word in string
----------------------
Enter String: This is testing in progress
Enter word to search: testing
Search Found index: 8

D:Java_Programs>javac SearchString.java
D:Java_Programs>java SearchString 
Search word in string
---------------------
Enter String: This is testing in progress
Enter word to search: searching
No Search Found!

Java Program to Search Word in a String from Right to Left

lastIndexOf method returns index if sub string is found in the string and matches from end to beginning of the string, otherwise returns -1.

import java.util.Scanner;

public class SearchString {
	public static void main(String[] args){
		Scanner sc=new Scanner(System.in);
		System.out.println("Search word in string from right to left"); 
		System.out.println("------------------------------------------"); 
		System.out.print("Enter String: "); 
		String str = sc.nextLine();
		System.out.print("Enter word to search: ");
		String word =sc.next();
		
		int index = str.lastIndexOf(word); 
		if(index >= 0){
			System.out.print("Search Found index: ");
			System.out.println(index);
		} else {
			System.out.println("No Search Found!");
		}	
	}
}

Output:

D:Java_Programs>javac SearchString.java
D:Java_Programs>java SearchString 
Search word in string from right to left
------------------------------------------
Enter String: This is testing codingpointer.com and is to identify issues!
Enter word to search: is
Search Found index: 53

D:Java_Programs>javac SearchString.java
D:Java_Programs>java SearchString 
Search word in string from right to left
------------------------------------------
Enter String: This is testing in progress
Enter word to search: searching
No Search Found!