String Functions in Java

Introduction

 

A string is a sequence of characters. Strings are very important in Java. There are various methods of strings in Java. Some of them are as follows.

 

Creation of string

 

We can create a string in Java in the following way.

package demo99;
public class Demo99 {
 public static void main(String args[]) {
  String abc = "one way of creation";
  String bcd = new String("another way of creation");
  System.out.println(abc);
  System.out.println(bcd);
 }
}

Output

 

 

 

Copying Values of Array to String

 

We can copy the values contained by an array to the specified string in the following manner.

package demo99;
public class Demo99 {
 public static void main(String args[]) {
  char ch[] = {'c','o','m', 'p','u','t','e','r'};
  String Str = String.copyValueOf(ch);
  System.out.println(Str);
 }
}

Output

 

 

 

Concatenation of Two Strings

 

There is a simple concat() method for the concatenation of strings in Java or we can also concat them in the following manner.

package demo99;
public class Demo99 {
 public static void main(String args[]) {
  String a = "COMPUTER ";
  String b = "SCIENCE";
  String c = a + b;
  System.out.println("from first way    " + c);
  System.out.println("\n");
  c = a.concat(b);
  System.out.println("from second way   " + c);
 }
}

Output

 

 

 

Comparing Two Strings

 

We can compare two strings using the equals() method as follows.

package demo99;
public class Demo99 {
 public static void main(String args[]) {
  String a = "COMPUTER";
  String b = "COM";
  String c = "COMPUTER";
  if (a.equals(b)) {
   System.out.println("strings are equal");
  } else {
   System.out.println("strings are not equal");
  }
  if (a.equals(c)) {
   System.out.println("strings are equal");
  } else {
   System.out.println("strings are not equal");
  }
 }
}

Output

 

 

 

Getting Index of a Character or String From Other String

 

We can determine the index of a specific character or string from the other string using the indexOf() method in the following way. 

package demo99;
public class Demo99 {
 public static void main(String args[]) {
  String a = "COMPUTER";
  System.out.println("Index of character 'T' is " + a.indexOf('T'));
  System.out.println("Index of string 'PUT' is " + a.indexOf("PUT"));
 }
}

Output

 

Replacing Characters in the String

 

We can easily replace a character in the string with another character using the replace() method as follows.

package demo99;
public class Demo99 {
 public static void main(String args[]) {
  String a = "COMPUTER";
  System.out.println("Index of character 'T' is " + a.indexOf('T'));
  System.out.println("Index of string 'PUT' is " + a.indexOf("PUT"));
 }
}

Output

 

 

 

Changing the Case of Characters of the String

 

We can change the case of the characters of the string by using the toLowerCase() and toUpperCase() methods as follows.

package demo99;
public class Demo99 {
 public static void main(String args[]) {
  String abc = "COMPUTER";
  System.out.println("To Lower Case: " + abc.toLowerCase());
  System.out.println("To Upper Case: " + abc.toUpperCase());
 }
}

Output

 

 

Summary

 

This article explains the various string functions in Java.