Java Tutorials

• Exercise
• Exercise

StringBuffer class

• The StringBuffer class is often used when you need the ability to modify strings in your programs.
• Manipulating a StringBuffer can be faster than creating-re-creating String objects during heavy text manipulation.
• StringBuffer objects are mutable.
• Useful methods include append(), charAt(), indexOf(), insert(), length(), and replace().

Exercise

• What is the output of the following class?

  class StringTest {
     public static void main (String args[]) {
        String str1 = null;
        String str2 = null;
        str1 = "Fred";
        str2 = str1;
        System.out.println("str1: " + str1);
        System.out.println("str2: " + str2);
        
        str1 = "Barney";
        System.out.println("str1: " + str1);
        System.out.println("str2: " + str2);
     }
  }
  

Exercise

• Modify the Hello application so it reads the a user's name from the command line, and writes the user's name as part of the output.
• Here is the source code for the original class:

  public class Hello
  {
    public static void main(String[] args) {
      System.out.println( "Hello, world" );
    }
  }
  

• Assuming that the users name is Al, after the changes the output of the program should be:

  Hello, Al