1) String s = new String();
2) Char chars[ ] = { ‘a’, ‘b’, ‘c’ };
String s = new String(chars);
3) String(char chars[ ], int startIndex, int numChars)
Here, startIndex specifies the index at which the subrange begins, and numChars
specifies the number of characters to use. Here is an example:
4) Char chars[ ] = { ‘a’, ‘b’, ‘c’, ‘d’, ‘e’, ‘f’ };
String s = new String(chars, 2, 3);
5) String(String strObj)
String Methods
| Method call | Task performed |
|---|---|
| s2 = s1.toLowerCase; | Converts the string to all lowercase |
| s2 = s1.toUpperCase; | Converts the string to all uppercase |
| s2 = s1.replace(‘ x ‘ , ‘ y ‘ ); | Replace all appearance of x with y |
| s2 = s1.trim(); | Remove white spaces at the beg and end of the string s1 |
| s1.equals ( s2 ); | Returns ‘ true ‘ if s1 is equal to s2 |
| s1.equalsIgnoreCase ( s2 ) | Returns ‘ true ‘ if s1 = s2, ignoring the case of characters |
| s1.length () | Gives the length of s1 |
| s1.CharAt ( n ) | Gives nth character of s1 |
| s1.CompareTo( s2 ) | Return – ve if s1 < s2, + ve if s1 > s2 and zero if s1 = s2 |
| s1.concat ( s2) | Concatenates s1 and s2 |
| s1.substring( n ) | Gives substring starting from nth character |
| s1.substring( n , m ) | Gives substring start from nth character up to mth(exclud mth) |
| String.ValueOf ( p ) | Creates a string object of the parameter p(simple or object) |
| p.toString () | Creates a string representation of the object p |
| s1.indexOf( ‘ x ‘ ) | Gives the position of the first occurrence of ‘x’ in the string s1 |
| s1.indexOf( ‘ x ‘ , n) | Gives the pos of ‘ x ‘ that occurs after nth position in string s1 |
| String.ValueOf ( var) | Converts the parameter value to string representation |
StringBuffer represents growable and writeable character sequences. StringBuffer may have characters and substrings inserted in the middle or appended to the end. StringBuffer will automatically grow to make room for such additions and often has more characters preallocated than are actually needed.
StringBuffer Constructors
StringBuffer defines these three constructors:
- StringBuffer( )
- StringBuffer(int size)
- StringBuffer(String str)
| Method call | Task performed |
|---|---|
| s1.setCharAt ( ' n ' , ' x ' ) | Modified the nth character to x |
| s1.append (s2) | Appends the string s2 to s1 at the end |
| s1.insert ( n , s2 ) | Inserts the string s2 at the nth position of string s1 |
| s1.setLength ( n ) | Sets the length of the string s1 to n |
| s1.getChars(sourceStart,sourceEnd, target[ ],targetStart) | Gives reversed characters in stringBuffer object |
| s1.reverse(); | Gives reversed characters in stringBuffer object |
| s1.replace(startIndex,endIndex,str) | The substring being replaced is specified by the indexes startIndex and endIndex. |
| s1.delete(startIndex, endIndex) | The substring being replaced is specified by the indexes startIndex and endIndex. |
| s1.substring(startIndex,endIndex) | The substring being replaced is specified by the indexes startIndex and endIndex. |