Chapter 4 Practice cont.

Practice with nested loops 1.What will be the output of the following program segment: 1.for (int i = 1; i <5; i++) { for (int j = 1; j < 5; j++) System.out.print (2*i+j + “ “); System.out.println(); } 2.for (int i = 1; i <5; i++) { for (int j = 0; j <= i; j++) System.out.print (2*i+j + “ “); System.out.println(); }

Practice with File input and output 1.Write code that does the following: opens a file named MyName.txt, writes your name to the file, then closes the file. 2.Write code that does the following: opens a file named MyName.txt, reads the first line from the file and displays it, then closes the file. 3.A text file contains a sequence of integers, each in a separate line. Write code that reads this file and displays the sum of all numbers in the file.

Practice with Random class 1.Write code to display a random number in the interval [0, 1). 2.Write code to display a random number in the interval [0, 100). 3.Write code to display a random number in the interval [13, 19] (teenager) 4.Write code to display a random letter [A..Z] 5.Write code to display a string of 5 random letters.

Sample Problems 1.The sum S(n) is defined as: S(n) = 1 + ½ + 1/3 + … + 1/n. Write a program that reads a number M from keyboard, then displays the smallest value of n so that S(n) >= M. 2.Write a program to calculate the square root of a non-negative number n, using the while loop. Compare the result with the Math.sqrt() method. See instructions in class.