Strings in Java

String is a class of package java.lang which is used to store a set of characters or words.

String class also contains pre-defined methods for String or word operations like copying, merging, finding length of a string, etc.

We don't need to import any class or package to use String, since java.lang classes will be imported by java compiler by default.

Possible usages of Strings

String str="123";

String str="123"+"2";

String a="123"; String s=a+"567";

char a[]={'a','b','c'};

String nstr=new String("123");

System.out.print("Hi"+a);

Important constructors of String class are

String()

It is used to create a new String object with empty value.

Example

class StringTest{

public static void main(String args[]){

String str=new String();

str="123";

System.out.println("The value of variable str is "+str);

}

Output

The value of variable str is 123

String(char[] value)

It is used to create a new String object with character array value.

We can use this to convert a character array to String.

Example

class StringTest{

public static void main(String args[]){

char a[]={'a','b','c'};

String str=new String(a);

System.out.println("The value of variable str is "+str);

}

Output

The value of variable str is abc

String(char[] value,int offset,int count)

It is used to create a new String object with character array value from the offset position to the number of characters.

Example

class StringTest{

public static void main(String args[]){

char a[]={'a','b','c','d'};

String str=new String(a,2,2);

System.out.println("The value of variable str is "+str);

}

Output

The value of variable str is cd

String(String str)

It is used to create a new String object with existing String object value.

Example

class StringTest{

public static void main(String args[]){

char a[]={'a','b','c','d'};

String estr=new String(a);

String str=new String(estr);

System.out.println("The value of variable str is "+str);

}

Output

The value of variable str is abcd

String(StringBuilder str)

It is used to create a new String object with existing StringBuilder class object value

We can use this to convert a StringBuilder object to String.

Example

class StringTest{

public static void main(String args[]){

StringBuilder builder=new StringBuilder("123");

String str=new String(builder);

System.out.println("The value of variable str is "+str);

}

Output

The value of variable str is 123

String(StringBuffer str)

It is used to create a new String object with existing StringBuffer class object value

We can use this to convert a StringBuffer object to String.

Example

class StringTest{

public static void main(String args[]){

StringBuffer buffer=new StringBuffer("123");

String str=new String(buffer);

System.out.println("The value of variable str is "+str);

}

Output

The value of variable str is 123

String(byte[] byte)

It is used to create a new String object with byte array value

We can use this to convert a byte array to String.

class StringTest{

public static void main(String args[]){

byte a[]={'a','b','c'};

String str=new String(a);

System.out.println("The value of variable str is "+str);

}

Output

The value of variable str is abc

String(byte[] value,int offset,int count)

It is used to create a new String object with byte array value from the offset position to the number of bytes.

Example

class StringTest{

public static void main(String args[]){

byte a[]={'a','b','c','d'};

String str=new String(a,2,2);

System.out.println("The value of variable str is "+str);

}

Output

The value of variable str is cd

Methods of String Class are

char charAt(int index)
int codePointAt(int index)
int codePointBefore(int index)
int codePointCount(int beginIndex, int endIndex)
int compareTo(String anotherString)
int compareToIgnoreCase(String str)
String concat(String str)
boolean contains(CharSequence s)
boolean contentEquals(CharSequence cs)
boolean contentEquals(StringBuffer sb)
static String copyValueOf(char[] data)
static String copyValueOf(char[] data, int offset, int count)
boolean endsWith(String suffix)
boolean equals(Object anObject)
boolean equalsIgnoreCase(String anotherString)
static String format(Locale l, String format, Object... args)
static String format(String format, Object... args)
byte[] getBytes()
byte[] getBytes(Charset charset)
byte[] getBytes(String charsetName)
void getChars(int srcBegin, int srcEnd, char[] dst, int dstBegin)
int hashCode()
int indexOf(int ch)
int indexOf(int ch, int fromIndex)
int indexOf(String str)
int indexOf(String str, int fromIndex)
String intern()
boolean isEmpty()
int lastIndexOf(int ch)
int lastIndexOf(int ch, int fromIndex)
int lastIndexOf(String str)
int lastIndexOf(String str, int fromIndex)
int length()
boolean matches(String regex)
int offsetByCodePoints(int index, int codePointOffset)
boolean regionMatches(boolean ignoreCase, int toffset, String other, int ooffset, int len)
boolean regionMatches(int toffset, String other, int ooffset, int len)
String replace(char oldChar, char newChar)
String replace(CharSequence target, CharSequence replacement)
String replaceAll(String regex, String replacement)
String replaceFirst(String regex, String replacement)
String[] split(String regex)
String[] split(String regex, int limit)
boolean startsWith(String prefix)
boolean startsWith(String prefix, int toffset)
CharSequence subSequence(int beginIndex, int endIndex)
String substring(int beginIndex)
String substring(int beginIndex, int endIndex)
char[] toCharArray()
String toLowerCase()
String toLowerCase(Locale locale)
String toString()
String toUpperCase()
String toUpperCase(Locale locale)
String trim()
static String valueOf(boolean b)
static String valueOf(char c)
static String valueOf(char[] data)
static String valueOf(char[] data, int offset, int count)
static String valueOf(double d)
static String valueOf(float f)
static String valueOf(int i)
static String valueOf(long l)
static String valueOf(Object obj)

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