How computers solve problems

  • Computers often solves problems by:

    • Repeatedly executing the same sequence of instructions

  • A commonly used problem solving techniques in Computer Science is:

      • The brute force search technique where the computer program check every possible solution...

  • The programming language construct to make a computer program repeat a series of instructions is:

    • A loop

  • Warning:

    • You can make a loop that never ends (a.ka. an infinite loop)

    • In that case, you computer program will never stop

Making a computer program execute some statements repeatedly

  • The while-statement is one of the 3 types of loop statements in Java.

    Example: this Java program will print "Hello World" 4 times: 

    public class While 
{
   public static void main(String[] args) 
   {
      int i;

      i = 0;
      while ( i < 4 )
      {
         System.out.println("Hello World");
         i++;
      }
   }
}

DEMO: demo/05-loops/01-intro/While.java      (step in BlueJ)

Overview of the loop statements in Java

  • There are 3 different loop statements in Java:

      1. The while-statement

      2. The do-while-statement

      3. The for-statement

    Each type of loop statement is designed for some special situation (problem)

  • We will study all of them in this chapter