There are three ways to use classes from other packages in Java: 1. Import the package member using an import statement 2. Import the entire package using an import statement 3. Refer to the member by its fully qualified name without using an import statement

1. Using Classes from Other Packages
• One of the 3 ways can be used:
• Import the package member using import
statement
• Import the member's entire package using
import statement
• Refer to the member by its fully qualified name
(without using import statement)
1

2. Importing Classes from Packages
• To use classes from other package, you need to
import the package of those classes
• By default, all Java programs import the
java.lang.* package
• you can use classes like String and Integer
inside the program even though you haven't
imported any packages
• The import statement is used to import classes from
packages
• There can be any number of import statements in a
source file
2

3. Importing Classes from Packages Contd..
• The syntax of import statement is
import <nameOfPackage>;
• nameOfPackage is any user defined or system
defined package name
• eg. :
• // Importing a class a Date class
• import java. util. Date
• // Importing all classes in java. util package
• import java. util.*;
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4. import javax.swing.*; Example Program
public class SumArray {
public static void main( String Output
args[] ) {
int a[] = { 1, 2, 3, 4, 5, 6};
int total = 0;
for ( int i = 0; i < a.length; i++ )
total += a[ i ];
OptionPane.showMessageDialog
( null, "Total of array elements: " Importing entire
+ total, "Sum the Elements of an package
Array", JOptionPane.INFORMATI
ON_MESSAGE );
System.exit( 0 );
}
}
4

5. Another Example Program
package MyPack; Package in
public class Balance { which Balance Test is other
String name; class is defined package test; package
double bal;
import MyPack.Balance;
public Balance(String n, double b) {
name = n; Importing a
class TestBalance { package member
bal = b; public static void main(String[ ] args)
} {
public void show() { Balance test Bal=
if(bal<0) new Balance("J.
System .out.print("-->> "); J. Jaspers", 99.88);
System.out.println(name + ": $" + testBal.show();
bal); }
} }
}
Output
5

6. Fully Qualified Name
• Another approach to use a class from other packages
• No import statement is used
• Fully Qualify the name of the class
• The following example illustrates:
• public static void main(String[] args) {
• java.util.Date x = new java.util.Date();
• System.out.println(“Today’s Date : “+
x.toString());
}
Date class is
fully qualified
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7. Example Program
package MyPack; package test;
Package in
public class Balance { which Balance Test is other
String name; class TestBalance { package
class is defined
double bal; public static void main(String[ ] args)
public Balance(String n, double b) { {
name = n; MyPack.Balance testBal =
bal = b; new MyPack.Balance("J.
} J. Jaspers", 99.88);
public void show() { testBal.show();
if(bal<0) }
System.out.print("-->> "); }
Fully qualifying class
System.out.println(name + ": $" + name
bal);}}
Output
7