Introduction for String
String This is a 'Non-primitive' Data Type for Java. String; There is a group of more than one character. String is written inside double quotes ("").
String these class; java.lang is defined in this package. In C and C ++, character data type and array were used for String. But String object is created in Java.
String is also created in Java like C and C ++.
For example
Source Code:public class Sample {
public static void main (String args []) {
char str1 [] = {'H', 'e', 'l', 'l', 'o', '', 'W', 'o', 'r', 'l', 'd'};
String s = new String (str1);
// both are same.
String str2 = "Hello World";
System.out.println ("String 1:" + s);
System.out.println ("String 2:" + str2);
}
}
Output:String 1: Hello World
String 2: Hello World
String Literal is close in double quotes ("").
For eg.String str = "Hello World";
String Object; How is the store done?
When string literal is used with string object, then string literal; There is a store on string pool.
String Pool This is a special memory to store string object.
for eg.String str1 = "Hello World";

In the following program, two different objects are stored on the string pool.
for eg.String str1 = "Hello";
String str2 = "Hello World";

When two objects are created with the same string, then both objects return the same string literal from the string pool.
for eg.String str1 = "Hello World";
String str2 = "Hello World";

There are many methods for String class in Java.
Java String Methods
Return type and String Methods | Description |
---|---|
boolean contentEquals (StringBuffer strbuff) | String is compared to string buffer and this method returns the boolean value. |
boolean endsWith (String suffix) | In string, the suffix of end is returned to boolean value. |
boolean equals (Object obj) | The two string is compared and boolean value; Return occurs. |
boolean equalsIgnoreCase (String str) | The two string is compared and boolean value; Return occurs. |
boolean matches (string regex) | String boolean value according to whether or not a given regular expression matches. Return occurs. |
boolean regionMatches (boolean ignoreCase, int startIndex, string str, int str_startIndex, int len) | The substring of two string or string is compared. |
boolean regionMatches (int startIndex, String str, int str_StartIndex, int len) | The substring of two string or string is compared. |
boolean startsWith (String prefix) | boolean value by checking string prefix; Returns are made. |
boolean startsWith (String prefix, int startIndex) | boolean value by checking string prefix; Returns are made. |
[byte] getBytes () | Byte array is returned from string. |
char charAt (int index) | Returns the character at the given index. |
char [] toCharArray () | The string is converted into a character array. |
CharSequence subSequence (int beginIndex, int endIndex) | The character sequence is returned. |
int compareTo (Object obj) | String is compared to another object. |
int compareTo (String str2) | String is compared to another string. |
int compareToIgnoreCase (String str2) | String is compared to another string. |
int indexOf (String str) | index of string character or substring; Return is done in integer. |
int indexOf (String str, int fromIndex) | index of string character or substring from starting Index; Return is done in integer. |
int indexOf (int ch) | index of string character; Return is done in integer. |
int indexOf (int ch, int fromIndex) | index of string character or substring from starting Index; Return is done in integer. |
int lastIndexOf (String str) | index of string or substring; Return is done in integer. |
int lastIndexOf (String str, int fromIndex) | index of string character or substring from starting Index; Return is done in integer. |
int lastIndexOf (int ch) | index of string character; Return is done in integer. |
int lastIndexOf (int ch, int fromIndex) | index of string character from starting Index; Return is done in integer. |
int length () | The length of string is returned in integer. |
void getChars (int srcBegin, int srcEnd, char [] dest, int destBegin) | string; The character array is copied. |
static String copyValueOf (char [] data) | character array; string is returned. |
static String copyValueOf (char [] data, int offset, int count) | character array; string is returned. |
static String valueOf (basic data type) | character array; string is returned. |
String concat (String str) | Different types are converted to string. |
String intern () | The canonical representation of string returns. |
String replace (char oldChar, char newChar) | The string is replaced with the given character. |
String replaceAll (String regex, String replacement) | Replaces string with regular expression. |
String replaceFirst (String regex, String replacement) | Replaces string with regular expression. |
String substring (int beginIndex) | The substring is made from string. |
String substring (int beginIndex, int endIndex) | The substring is made from string. |
String toLowerCase () | Converts all uppercase letters to lowercase. |
String toUpperCase () | Converts all lowercase letters to uppercase. |
String trim () | The beginning and end whitespaces are removed. |
String [] split (String regex) | The array of that string by creating a separate substring from the regular expression of the string; Return is done. |
String [] split (String regex, int limit) | The array of that string by creating a separate substring from the regular expression of the string; Return is done. |
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