Sometimes you want to check for a number of related conditions and choose one of several actions. One way to do this is by chaining a series of ifs and elses. Look at the following code segment : if (x > 0) { System.out.println(“x is positive”); } else if (x < 0) { System.out.println(“x is negative”); }…
Prior to Java SE 7, you can use a finally block to ensure that a resource is closed regardless of whether the try statement completes normally or abruptly. In Java SE 7 or later you can use try-with-resources statement to ensure that each resource is closed at the end of the statement. Following program explains this : import java.io.FileReader;…
It is often necessary to compare strings to see if they are the same, or to see which comes first in alphabetical order. It would be nice if we could use the comparison operators, like == and >, but we can’t. To compare Strings, we have to use the equals and compareTo methods. Syntax for using method compareTo : str1.compareTo(str2); The…
Accepting keyboard input in Java is done using a Scanner object. Consider the following statement Scanner console = new Scanner(System.in) This statement declares a reference variable named console. The Scanner object is associated with standard input device (System.in). To get input from keyboard, you can call methods of Scanner class. For example in following statment…
In Section 2.5, you learned how to use a Scanner object to input data from the standard input device (keyboard). Recall that the following statement creates the Scanner object console and initializes it to the standard input device: Scanner console = new Scanner(System.in); You can also use the Scanner class to read input from a file….
Writing Data to a Text File The simplest way to write text to a file requires us to use PrintWriter class from the standard package java.io . The class PrintWriter has the familiar print() and println() methods we have been using for writing to the console. The following program writes the name of four oceans…
Introduction to File Input and Output Data stored in variables and arrays is temporary — it’s lost when the program terminates. Java allows a program to read data from a file or write data to a file. Once the data is saved in a file on computer disk, it will remain there after the program…
File Input Output 10.1 Introduction to File Input and Output 10.2 Writing Data to Text File 10.3 Reading Data from Text File 10.4 Reading and Writing Premitive Data
Consider the following statement: X = 5 + 30 * 10 x will store 305. In this equation, the numbers 30 and 10are multiplied first, and the number 5 is added to their product. Multiplication, division and modulus have higher order than addition and subtraction, which means that they’re performed first. If two operators sharing…
1.1 Getting Started In order to teach you about java programming, we assume that you’ve done little or no programming in the past and you are using a machine running Windows. What you need To write all our code, we’ll use Notepad, a simple editor included with the Windows platforms. In order to run Java programs,…
