And the other in which only a particular member of a class is imported.
Syntax
import static packageName.ClassName.membername;
For example:
import static java.lang.Math.*;
public class StaticImportTest
{
public static void main( String args[] )
{
System.out.println( “Square root of 400 =”+sqrt(400.0 ) );
}
}
StringBuilder
StringBuilder is a class, which is very similar to the StringBuffer class. It is a new concept introduced in J2SE 5. Like the String and the StringBuffer classes, it extends directly from the Object class. The StringBuilder class can act as an alternative to StringBuffer in places where the environment is not multithreaded, i.e, where synchronization or multithreading is not significant. The signature of the StringBuilder class is as follows:
public final class StringBuilder extends Object implements Serializable, CharSequence
Since StringBuilder is not synchronized, it offers faster performance than StringBuffer.
An example of using StringBuilder is given below:
import java.util.*;
public class StrBld
{
public static String likeJava(List list)
{
StringBuilder b = new StringBuilder();
for (Iterator i = list.iterator(); i.hasNext(); )
{
b.append(i.next()).append(” “);
}
return b.toString();
}
public static void main(String[] args)
{
List list = new ArrayList();
list.add(“I”);
list.add(“like”);
list.add(“java”);
System.out.println(StrBld.likeJava(list));
}
}
This will compile and execute to give the output “I like java”.
Some of the important methods of StringBuilder class are as follows:
public StringBuilder append(char c)
It appends the string representation of the char argument to the current sequence.
The argument is appended to the contents of this sequence. It increases the length of the sequence by 1.
public int capacity()
This will return the current capacity of the StringBuider.
public StringBuilder insert(int offset,boolean b)
This will insert the string representation of the boolean argument into current sequence.
public StringBuilder reverse()
This will cause the character sequence to be replaced by the reverse of the sequence.
public String toString()
This will return a string representing the data in current sequence
public StringBuilder replace(int start, int end, String str)
This will replace the characters in a substring of this sequence with characters in the specified String. The substring begins at the specified start and extends to the character at index end – 1 or to the end of the sequence if no such character exists.
free study material for CX310-055 OCP Java SE 5 Programmer exam.
