Java Program That Reads Text File and What Index of the Line the String Occurs

Java - Strings Class

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Strings, which are widely used in Java programming, are a sequence of characters. In Java programming language, strings are treated as objects.

The Java platform provides the Cord form to create and manipulate strings.

Creating Strings

The almost direct way to create a string is to write −

Cord greeting = "Hello world!";        

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 whatsoever other object, yous tin can create String objects by using the new keyword and a constructor. The Cord class has 11 constructors that allow you to provide the initial value of the string using dissimilar sources, such as an array of characters.

Example

Alive Demo

public course StringDemo {     public static void chief(Cord args[]) {       char[] helloArray = { 'h', 'due east', 'l', 'l', 'o', '.' };       String helloString = new Cord(helloArray);         System.out.println( helloString );    } }        

This will produce the post-obit upshot −

Output

how-do-you-do.        

Note − The String class is immutable, so that once it is created a String object cannot be changed. If there is a necessity to brand a lot of modifications to Strings of characters, then you should utilize Cord Buffer & String Builder Classes.

String Length

Methods used to obtain information most an object are known as accessor methods. 1 accessor method that yous can apply with strings is the length() method, which returns the number of characters contained in the string object.

The post-obit program is an example of length(), method Cord class.

Example

Alive Demo

public class StringDemo {     public static void main(String args[]) {       String palindrome = "Dot saw I was Tod";       int len = palindrome.length();       Organization.out.println( "String Length is : " + len );    } }        

This volition produce the following outcome −

Output

Cord Length is : 17        

Concatenating Strings

The String class includes a method for concatenating two strings −

string1.concat(string2);        

This returns a new string that is string1 with string2 added to it at the cease. You can likewise use the concat() method with string literals, equally in −

"My proper noun is ".concat("Zara");        

Strings are more commonly concatenated with the + operator, as in −

"Hello," + " world" + "!"        

which results in −

"Hello, globe!"        

Let us wait at the post-obit case −

Example

Live Demo

public course StringDemo {     public static void main(Cord args[]) {       String string1 = "saw I was ";       System.out.println("Dot " + string1 + "Tod");    } }        

This will produce the following result −

Output

Dot saw I was Tod        

Creating Format Strings

You take printf() and format() methods to print output with formatted numbers. The String course has an equivalent form method, format(), that returns a String object rather than a PrintStream object.

Using String's static format() method allows you to create a formatted string that you can reuse, as opposed to a one-time print statement. For example, instead of −

Example

Organisation.out.printf("The value of the bladder variable is " +                   "%f, while the value of the integer " +                   "variable is %d, and the string " +                   "is %s", floatVar, intVar, stringVar);        

You can write −

String fs; fs = String.format("The value of the bladder variable is " +                    "%f, while the value of the integer " +                    "variable is %d, and the string " +                    "is %s", floatVar, intVar, stringVar); System.out.println(fs);        

String Methods

Hither is the list of methods supported by String class −

Sr.No.	Method & Description
1	char charAt(int index) Returns the character at the specified index.
2	int compareTo(Object o) Compares this String to another Object.
3	int compareTo(String anotherString) Compares ii strings lexicographically.
4	int compareToIgnoreCase(String str) Compares ii strings lexicographically, ignoring case differences.
5	String concat(String str) Concatenates the specified string to the stop of this string.
6	boolean contentEquals(StringBuffer sb) Returns true if and but if this String represents the same sequence of characters as the specified StringBuffer.
vii	static String copyValueOf(char[] information) Returns a Cord that represents the character sequence in the array specified.
eight	static String copyValueOf(char[] data, int offset, int count) Returns a String that represents the character sequence in the array specified.
9	boolean endsWith(String suffix) Tests if this string ends with the specified suffix.
x	boolean equals(Object anObject) Compares this cord to the specified object.
11	boolean equalsIgnoreCase(String anotherString) Compares this String to another Cord, ignoring case considerations.
12	byte[] getBytes() Encodes this String into a sequence of bytes using the platform's default charset, storing the result into a new byte array.
13	byte[] getBytes(String charsetName) Encodes this String into a sequence of bytes using the named charset, storing the effect into a new byte array.
fourteen	void getChars(int srcBegin, int srcEnd, char[] dst, int dstBegin) Copies characters from this string into the destination character assortment.
15	int hashCode() Returns a hash code for this string.
sixteen	int indexOf(int ch) Returns the index inside this string of the beginning occurrence of the specified character.
17	int indexOf(int ch, int fromIndex) Returns the alphabetize within this string of the first occurrence of the specified character, starting the search at the specified index.
eighteen	int indexOf(String str) Returns the index inside this string of the outset occurrence of the specified substring.
nineteen	int indexOf(String str, int fromIndex) Returns the index within this string of the first occurrence of the specified substring, starting at the specified index.
20	String intern() Returns a canonical representation for the cord object.
21	int lastIndexOf(int ch) Returns the index within this cord of the concluding occurrence of the specified character.
22	int lastIndexOf(int ch, int fromIndex) Returns the alphabetize within this string of the final occurrence of the specified character, searching backward starting at the specified alphabetize.
23	int lastIndexOf(String str) Returns the index within this string of the rightmost occurrence of the specified substring.
24	int lastIndexOf(String str, int fromIndex) Returns the index within this string of the last occurrence of the specified substring, searching astern starting at the specified index.
25	int length() Returns the length of this string.
26	boolean matches(Cord regex) Tells whether or not this string matches the given regular expression.
27	boolean regionMatches(boolean ignoreCase, int toffset, String other, int ooffset, int len) Tests if two string regions are equal.
28	boolean regionMatches(int toffset, String other, int ooffset, int len) Tests if ii cord regions are equal.
29	Cord supersede(char oldChar, char newChar) Returns a new string resulting from replacing all occurrences of oldChar in this string with newChar.
30	String replaceAll(Cord regex, String replacement Replaces each substring of this cord that matches the given regular expression with the given replacement.
31	Cord replaceFirst(String regex, String replacement) Replaces the starting time substring of this string that matches the given regular expression with the given replacement.
32	Cord[] split(Cord regex) Splits this cord around matches of the given regular expression.
33	String[] separate(String regex, int limit) Splits this string around matches of the given regular expression.
34	boolean startsWith(Cord prefix) Tests if this string starts with the specified prefix.
35	boolean startsWith(String prefix, int toffset) Tests if this cord starts with the specified prefix offset a specified alphabetize.
36	CharSequence subSequence(int beginIndex, int endIndex) Returns a new grapheme sequence that is a subsequence of this sequence.
37	String substring(int beginIndex) Returns a new string that is a substring of this string.
38	Cord substring(int beginIndex, int endIndex) Returns a new string that is a substring of this string.
39	char[] toCharArray() Converts this string to a new character assortment.
40	Cord toLowerCase() Converts all of the characters in this String to lower instance using the rules of the default locale.
41	String toLowerCase(Locale locale) Converts all of the characters in this String to lower case using the rules of the given Locale.
42	Cord toString() This object (which is already a string!) is itself returned.
43	String toUpperCase() Converts all of the characters in this String to upper instance using the rules of the default locale.
44	Cord toUpperCase(Locale locale) Converts all of the characters in this Cord to upper example using the rules of the given Locale.
45	Cord trim() Returns a copy of the string, with leading and trailing whitespace omitted.
46	static String valueOf(primitive data blazon 10) Returns the string representation of the passed information blazon argument.

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Source: https://www.tutorialspoint.com/java/java_strings.htm

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