With an example explain the different string methods in java?

Answer 1

Strings, which are widely used in Java programming, are a sequence of characters. In the Java programming language, strings are objects. The Java platform provides the String class to create and manipulate strings. Creating Strings The most direct way to create a string is to write: String greeting = "Hello world!"; In this case, "Hello world!" is a string literal-a series of characters in your code that is enclosed in double quotes. Whenever it encounters a string literal in your code, the compiler creates a String object with its value-in this case, Hello world!. As with any other object, you can create String objects by using the new keyword and a constructor. The String class has 11 constructors that allow you to provide the initial value of the string using different sources, such as an array of characters: char[] helloArray = { 'h', 'e', 'l', 'l', 'o', '.'}; String helloString = new String(helloArray); System.out.println(helloString); The last line of this code snippet displays hello. Note: The String class is immutable, so that once it is created a String object cannot be changed. The String class has a number of methods, some of which will be discussed below, that appear to modify strings. Since strings are immutable, what these methods really do is create and return a new string that contains the result of the operation.

Answer 2

String class is the java class that is used for string manipulations. For ex: you want to display a greeting to the user based on his inputs for a set of questions like what is your name, where are you from etc. A sample message to the user could be:

"Hi Steve, how are you? Hope everyone is fine in Atlanta"

So here, this will not be one simple message. It will be parts. Like:

public String greetUser(String name, String city) {

return "Hi " + name + ", how are you? Hope everyone is fine in " + city;

}

Here we are doing a string manipulation where we are forming a string based on user inputs. Though we did not specifically declare or create a string, a string is what is being created/modified in this method.

Some of the methods in a string are:

a. Equals - to check if two strings are equal

b. subString - to pick out a specific portion of the string

c. length - to calculate the length of the string

Answer 3

Strings, which are widely used in Java programming, are a sequence of characters. In the Java programming language, strings are objects. The Java platform provides the String class to create and manipulate strings. Creating Strings The most direct way to create a string is to write: String greeting = "Hello world!"; In this case, "Hello world!" is a string literal-a series of characters in your code that is enclosed in double quotes. Whenever it encounters a string literal in your code, the compiler creates a String object with its value-in this case, Hello world!. As with any other object, you can create String objects by using the new keyword and a constructor. The String class has 11 constructors that allow you to provide the initial value of the string using different sources, such as an array of characters: char[] helloArray = { 'h', 'e', 'l', 'l', 'o', '.'}; String helloString = new String(helloArray); System.out.println(helloString); The last line of this code snippet displays hello. Note: The String class is immutable, so that once it is created a String object cannot be changed. The String class has a number of methods, some of which will be discussed below, that appear to modify strings. Since strings are immutable, what these methods really do is create and return a new string that contains the result of the operation.

Answer 4

String methods is the same as the int, char, double etc. methods...

we have four (4) methods in java namely:

1. methods without argument

2. methods with one argument

3. methods with multiple arguments and

4. methods that returns a value

Examples:

1. methods without argument

import java.io.*; //import packages

public class chuva //class name

{

public static void main(String a[]) throws Exception //main method

{

string1(); //call the string method without argument

}

public static void string1() throws Exception //method without argument

{

System.out.println("Ally Cha"); //print string

}

} //end class

2. methods with one argument

import java.io.*; //import packages

public class chuva2 //class name

{

public static void main(String a[]) throws Exception //main method

{

String ako = "Ally Cha"; //initialize the string

string2(ako); //call the string method with one argument

}

public static void string2(String hehe) throws Exception //method with one argument

{

System.out.println(hehe);

}

} //end class

3. methods with multiple argument

import java.io.*; //import packages

public class chuva3 //class name

{

public static void main(String a[]) throws Exception //main method

{

String ako = "Ally Cha"; //initialize the first string

String ikaw = "Philippines"; //initialize the second string

String tayo = "PUP Taguig"; //initialize the third string

string2(ako, ikaw, tayo); //call the string method with multiple argument

}

public static void string2(String hehe, String haha, String hoho) throws Exception //method with multiple argument

{

System.out.println(hehe+ " " +haha+ " " +hoho);

}

} //end class

4. methods that return a value argument

import java.io.*; //import packages

public class chuva4 //class name

{

public static void main(String a[]) throws Exception //main method

{

int x = 10; //initialize an integer

evenOddNeu(x);

}

public static String evenOddNeu(int num1) throws Exception //method that returns a String value

{

int modul;

modul = num1 % 2;

if (num1==0)

return "Neutral";

else if (modul == 0)

return "Even";

else

return "Odd";

}

} //end class

Answer 5

There are literally almost 100 methods of the string class and almost nobody knows all of them off the top of their head, however, i can name you some common ones:

*assume "str" is a String variable*

str.length() = returns length of the string (int)

str.substring(int a, int b) = returns string between a & b

str.charAt(int a) = returns (char) at point listed

str.replace(charAt(int a), string b) = replaces one letter with another

str.endsWith(string a) = returns boolean (checks if suffix of str = a)

str.equals(Anything here) = returns boolean (compares to another object)

str.toLowerCase(int a, int b) = pretty obvious

str.toUpperCase(int a, int b) = also pretty obvious

for further information regarding strings, see the websites in the related links section.

Answer 6

The following methods are some of the more commonly used methods in the String class, and also the ones that you're most likely to encounter on the exam. They are:

public char charAt(int index)

This method returns the character located at the String's specified index. String indexes are zero-based-for example,

String x = "Rocky";

System.out.println( x.charAt(2) ); // output is 'o'

public String concat(String s)

This method returns a String with the value of the String passed in to the method appended to the end of the String used to invoke the method-for example,

String x = "ferrari ";

System.out.println( x.concat(" car") ); // output is "ferrari car"

The overloaded + and += operators perform functions similar to the concat() method-for example,

String x = "ferrari";

System.out.println( x + " car"); // output is "ferrari car"

String x = "ferrari";

x+= " car";

System.out.println( x ); // output is "ferrari car"

In the preceding "ferrari car" example, notice that the value of x really did change! Remember that the += operator is an assignment operator, so line 2 is really creating a new String, "ferrari car", and assigning it to the x variable. After line 2 executes, the original String x was referring to, "ferrari", is abandoned.

public boolean equalsignoreCase(String s)

This method returns a boolean value (true or false) depending on whether the value of the String in the argument is the same as the value of the String used to invoke the method. This method will return true even when characters in the String objects being compared have differing cases-for example,

String x = "ferrari";

System.out.println( x.equalsIgnoreCase("FERRARI")); // is "true"

System.out.println( x.equalsIgnoreCase("BMW")); // is "false"

public int length()

This method returns the length of the String used to invoke the method-for example,

String x = "Rocky";

System.out.println( x.length() ); // returns "5"

public String replace(char old, char new)

This method returns a String whose value is that of the String used to invoke the method, updated so that any occurrence of the char in the first argument is replaced by the char in the second argument-for example,

String x = "ABABABABA";

System.out.println( x.replace('A', 'a') ); // output is

// "aBaBaBaBa"

public String toLowerCase()

This method returns a String whose value is the String used to invoke the method, but with any uppercase characters converted to lowercase-for example,

String x = "ROCKY";

System.out.println( x.toLowerCase() ); // output is "rocky"

public String toString()

This method returns the value of the String used to invoke the method. You are probably thinking why do I need a toString() method for a String? Isnt it useless or redundant? To answer you my friend, if you remember String is an Object and all java objects have a toString() method. And hence, eventhough the current object under consideration is a String, we still have a toString() method. For example:

String x = "Rocky";

System.out.println( x.toString() ); // output - "Rocky"

public String toUpperCase()

This method returns a String whose value is the String used to invoke the method, but with any lowercase characters converted to uppercase-for example,

String x = "rocky";

System.out.println( x.toUpperCase() ); // output is "ROCKY"

public String trim()

This method returns a String whose value is the String used to invoke the method, but with any leading or trailing blank spaces removed-for example,

String x = " Rock ";

System.out.println( x + "y" ); // result is " Rock y"

System.out.println( x.trim() + "y"); // result is "Rocky"