STRINGS - Introduction to Java Programming - page 361

The expression is passed as a string in one argument and it is split into three parts—
tokens[0] , tokens[1] , and tokens[2] —using the split method (line 15) with a space
as a delimiter.
Integer.parseInt(tokens[0]) (line 19) converts a digital string into an integer. The
string must consist of digits. If it doesn't, the program will terminate abnormally.
For this program to work, the expression must be entered in the form of “operand1 opera-
tor operand2”. The operands and operator are separated by exactly one space. You can mod-
ify the program to accept the expressions in different forms (see Programming Exercise 9.28).

9.22

✓ ✓

This topic declares the main method as

Check

Point

public static void main(String[] args)

Can it be replaced by one of the following lines?

public static void main(String args[])
public static void main(String[] x)
public static void main(String x[])
static void main(String x[])

9.23

Show the output of the following program when invoked using

1. java Test I have a dream

2. java Test “1 2 3”

3. java Test

public class Test {
public static void main(String[] args) {
System.out.println( "Number of strings is " + args.length);
for ( int i = 0 ; i < args.length; i++)
System.out.println(args[i]);

}

}

K EY T ERMS

interned string 337 wrapper class 350

C HAPTER S UMMARY
1. Strings are objects encapsulated in the String class. A string can be constructed
using one of the 13 constructors or simply using a string literal. Java treats a string lit-
eral as a String object.

2. A String object is immutable; its contents cannot be changed. To improve effi-
ciency and save memory, the JVM stores two literal strings that have the same char-
acter sequence in a unique object. This unique object is called an interned string
object .

3. You can get the length of a string by invoking its length() method, retrieve a char-
acter at the specified index in the string using the charAt(index) method, and use
the indexOf and lastIndexOf methods to find a character or a substring in a
string.