{"id":11250,"date":"2014-07-09T11:00:32","date_gmt":"2014-07-09T08:00:32","guid":{"rendered":"http:\/\/examples.javacodegeeks.com\/?p=11250"},"modified":"2022-07-06T14:24:40","modified_gmt":"2022-07-06T11:24:40","slug":"java-util-scanner-example","status":"publish","type":"post","link":"https:\/\/examples.javacodegeeks.com\/java-util-scanner-scanner-java-example\/","title":{"rendered":"java.util.Scanner – Scanner Java Example (with video)"},"content":{"rendered":"

In this example, we will show the range of functionality provided by the java.util.Scanner – Scanner Java class. We will also see how to use the Java Scanner class to read a Java input form the console. A simple text scanner which can parse primitive types and strings using regular expressions.<\/p>\n

You can also check this tutorial in the following video:<\/p>\n

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Scanner Java Example – Video<\/figcaption><\/figure>\n<\/div>\n

1. Introduction<\/h2>\n

A Scanner<\/a> breaks its input into tokens using a delimiter pattern, which by default matches whitespace.<\/p>\n

The resulting tokens may then be converted into values of different types using the various next methods.<\/p>\n

For example, this code allows a user to read a number from System.in<\/a><\/code>:<\/p>\n

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Scanner sc = <\/code>new<\/code> Scanner(System.in);<\/code><\/div>\n
int<\/code> i = sc.nextInt();<\/code><\/div>\n<\/div>\n<\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n<\/div>\n<\/div>\n

The scanner can also use delimiters other than whitespace. This example reads several items in from a string:<\/p>\n

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String input = <\/code>\"1 fish 2 fish red fish blue fish\"<\/code>;<\/code><\/div>\n
Scanner s = <\/code>new<\/code> Scanner(input).useDelimiter(<\/code>\"\\\\s*fish\\\\s*\"<\/code>);<\/code><\/div>\n
System.out.println(s.nextInt());<\/code><\/div>\n
System.out.println(s.nextInt());<\/code><\/div>\n
System.out.println(s.next());<\/code><\/div>\n
System.out.println(s.next());<\/code><\/div>\n
s.close();<\/code><\/div>\n<\/div>\n<\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n<\/div>\n<\/div>\n

The following code shows you how you can use the Java Scanner class to read a Java input form the console. To start, you create a Scanner object passing System.in<\/a><\/code> (which is the keyboard) as a parameter to the Constructor. Like the System.out<\/a><\/code> object, the System.in<\/a><\/code> object is created by Java automatically. Because of that, you can use this object with a Scanner object whenever you want to get a console input.<\/p>\n

Once you’ve created a Scanner<\/a><\/code> object, you can use the next methods to read data from the console. The method you use depends on the type of data you need to read. To read string data, for example, you use the next<\/em> method. To read integer data, you use the nextInt<\/em> method. To read double data, you use the the nextDouble<\/em> method. And to read all of the data on a line, you use the nextLine<\/em> method. When one of the methods of the Scanner<\/a><\/code> class is run, the application waits for the user to enter data with the keyboard. To complete the entry, the user presses the Enter<\/em> key.<\/p>\n

Since the Scanner<\/a><\/code> class is in the java.util<\/a><\/code> package, you’ll want to include an import statement whenever you use this class.<\/p>\n

2. Scanner Constructors<\/h2>\n

Here is a list of the Constructors in the Java scanner Class. <\/p>\n

\n\n\n\n\n\n\n\n\n\n\n\n\n\n
<\/th>\nConstructor<\/th>\nDescription<\/th>\n<\/tr>\n
1.<\/td>\nScanner(File source)<\/td>\nConstructs a new Scanner that produces values scanned from the specified file.<\/td>\n<\/tr>\n
2.<\/td>\nScanner(File source, String charsetName)<\/td>\nConstructs a new Scanner that produces values scanned from the specified file.<\/td>\n<\/tr>\n
3.<\/td>\nScanner(InputStream source)<\/td>\nConstructs a new Scanner that produces values scanned from the specified Java input stream.<\/td>\n<\/tr>\n
4.<\/td>\nScanner(InputStream source, String charsetName)<\/td>\nConstructs a new Scanner that produces values scanned from the specified Java input stream.<\/td>\n<\/tr>\n
5.<\/td>\nScanner(Path source)<\/td>\nConstructs a new Scanner that produces values scanned from the specified file.<\/td>\n<\/tr>\n
6.<\/td>\nScanner(Path source, String charsetName)<\/td>\nConstructs a new Scanner that produces values scanned from the specified file.<\/td>\n<\/tr>\n
7.<\/td>\nScanner(Readable source)<\/td>\nConstructs a new Scanner that produces values scanned from the specified source.<\/td>\n<\/tr>\n
8.<\/td>\nScanner(ReadableByteChannel source)<\/td>\nConstructs a new Scanner that produces values scanned from the specified channel.<\/td>\n<\/tr>\n
9.<\/td>\nScanner(ReadableByteChannel source, String charsetName)<\/td>\nConstructs a new Scanner that produces values scanned from the specified channel.<\/td>\n<\/tr>\n
10.<\/td>\nScanner(String source)<\/td>\nConstructs a new Scanner that produces values scanned from the specified string.\n<\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n<\/figure>\n

3. Scanner Methods<\/h2>\n

Here is a list of the Methods in the Java scanner class.<\/p>\n

\n\n\n\n\n\n\n\n\n\n\n\n\n\n\n\n\n\n\n\n\n\n\n\n\n\n\n\n\n\n\n\n\n\n\n\n\n\n\n\n\n\n\n\n\n\n\n\n\n\n\n\n\n\n\n\n\n\n
<\/th>\nReturn Type<\/th>\nMethod Name<\/th>\nDescription<\/th>\n<\/tr>\n
1.<\/td>\nvoid<\/td>\nclose()<\/td>\nCloses this scanner.<\/td>\n<\/tr>\n
2.<\/td>\nPattern<\/td>\ndelimiter()<\/td>\nReturns the Pattern this Scanner is currently using to match delimiters.<\/td>\n<\/tr>\n
3.<\/td>\nString<\/td>\nfindInLine(String pattern)<\/td>\nAttempts to find the next occurrence of a pattern constructed from the specified string, ignoring delimiters.<\/td>\n<\/tr>\n
4.<\/td>\nString<\/td>\nfindInLine(Pattern pattern)<\/td>\nAttempts to find the next occurrence of the specified pattern ignoring delimiters.<\/td>\n<\/tr>\n
5.<\/td>\nString<\/td>\nfindWithinHorizon(Pattern pattern, int horizon)<\/td>\nAttempts to find the next occurrence of the specified pattern.<\/td>\n<\/tr>\n
6.<\/td>\nString<\/td>\nfindWithinHorizon(String pattern, int horizon)<\/td>\nAttempts to find the next occurrence of a pattern constructed from the specified string, ignoring delimiters.<\/td>\n<\/tr>\n
7.<\/td>\nboolean<\/td>\nhasNext()<\/td>\nReturns true if this scanner has another token in its input.<\/td>\n<\/tr>\n
8.<\/td>\nboolean<\/td>\nhasNext(Pattern pattern)<\/td>\nReturns true if the next complete token matches the specified pattern.<\/td>\n<\/tr>\n
9.<\/td>\nboolean<\/td>\nhasNext(String pattern)<\/td>\nReturns true if the next token matches the pattern constructed from the specified string.<\/td>\n<\/tr>\n
10.<\/td>\nboolean<\/td>\nhasNextBigDecimal()<\/td>\nReturns true if the next token in this scanner’s Java input can be interpreted as a BigDecimal using the nextBigDecimal() method.<\/td>\n<\/tr>\n
11.<\/td>\nboolean<\/td>\nhasNextBigInteger()<\/td>\nReturns true if the next token in this scanner’s input can be interpreted as a BigInteger in the default radix using the nextBigInteger() method.<\/td>\n<\/tr>\n
12.<\/td>\nboolean<\/td>\nhasNextBigInteger(int radix)<\/td>\nReturns true if the next token in this scanner’s input can be interpreted as a BigInteger in the specified radix using the nextBigInteger() method.<\/td>\n<\/tr>\n
13.<\/td>\nboolean<\/td>\nhasNextBoolean()<\/td>\nReturns true if the next token in this scanner’s input can be interpreted as a boolean value using a case insensitive pattern created from the string “true|false”.<\/td>\n<\/tr>\n
14.<\/td>\nboolean<\/td>\nhasNextByte()<\/td>\nReturns true if the next token in this scanner’s input can be interpreted as a byte value in the default radix using the nextByte() method.<\/td>\n<\/tr>\n
15.<\/td>\nboolean<\/td>\nhasNextByte(int radix)<\/td>\nReturns true if the next token in this scanner’s input can be interpreted as a byte value in the specified radix using the nextByte() method.<\/td>\n<\/tr>\n
16.<\/td>\nboolean<\/td>\nhasNextDouble()<\/td>\nReturns true if the next token in this scanner’s input can be interpreted as a double value using the nextDouble() method.<\/td>\n<\/tr>\n
17.<\/td>\nboolean<\/td>\nhasNextFloat()<\/td>\nReturns true if the next token in this scanner’s input can be interpreted as a float value using the nextFloat() method.<\/td>\n<\/tr>\n
18.<\/td>\nboolean<\/td>\nhasNextInt()<\/td>\nReturns true if the next token in this scanner’s input can be interpreted as an int value in the default radix using the nextInt() method.<\/td>\n<\/tr>\n
19.<\/td>\nboolean<\/td>\nhasNextInt(int radix)<\/td>\nReturns true if the next token in this scanner’s input can be interpreted as an int value in the specified radix using the nextInt() method.<\/td>\n<\/tr>\n
20.<\/td>\nboolean<\/td>\nhasNextLine()<\/td>\nReturns true if there is another line in the input of this scanner.<\/td>\n<\/tr>\n
21.<\/td>\nboolean<\/td>\nhasNextLong()<\/td>\nReturns true if the next token in this scanner’s input can be interpreted as a long value in the default radix using the nextLong() method.<\/td>\n<\/tr>\n
22.<\/td>\nboolean<\/td>\nhasNextLong(int radix)<\/td>\nReturns true if the next token in this scanner’s input can be interpreted as a long value in the specified radix using the nextLong() method.<\/td>\n<\/tr>\n
23.<\/td>\nboolean<\/td>\nhasNextShort()<\/td>\nReturns true if the next token in this scanner’s input can be interpreted as a short value in the default radix using the nextShort() method.<\/td>\n<\/tr>\n
24.<\/td>\nboolean<\/td>\nhasNextShort(int radix)<\/td>\nReturns true if the next token in this scanner’s input can be interpreted as a short value in the specified radix using the nextShort() method.<\/td>\n<\/tr>\n
25.<\/td>\nIOException<\/td>\nioException()<\/td>\nReturns the IOException last thrown by this Scanner’s underlying Readable.<\/td>\n<\/tr>\n
26.<\/td>\nLocale<\/td>\nlocale()<\/td>\nReturns this scanner’s locale.<\/td>\n<\/tr>\n
27.<\/td>\nMatchResult<\/td>\nmatch()<\/td>\nReturns the match result of the last scanning operation performed by this scanner.<\/td>\n<\/tr>\n
28.<\/td>\nString<\/td>\nnext()<\/td>\nFinds and returns the next complete token from this scanner.<\/td>\n<\/tr>\n
29.<\/td>\nString<\/td>\nnext(Pattern pattern)<\/td>\nReturns the next token if it matches the specified pattern.<\/td>\n<\/tr>\n
30.<\/td>\nString<\/td>\nnext(String pattern)<\/td>\nReturns the next token if it matches the pattern constructed from the specified string.<\/td>\n<\/tr>\n
31.<\/td>\nBigDecimal<\/td>\nnextBigDecimal()<\/td>\nScans the next token of the input as a BigDecimal.<\/td>\n<\/tr>\n
32.<\/td>\nBigInteger<\/td>\nnextBigInteger()<\/td>\nScans the next token of the input as a BigInteger.<\/td>\n<\/tr>\n
33.<\/td>\nBigInteger<\/td>\nnextBigInteger(int radix)<\/td>\nScans the next token of the input as a BigInteger.<\/td>\n<\/tr>\n
34.<\/td>\nboolean<\/td>\nnextBoolean()<\/td>\nScans the next token of the input into a boolean value and returns that value.<\/td>\n<\/tr>\n
35.<\/td>\nbyte<\/td>\nnextByte()<\/td>\nScans the next token of the input as a byte.<\/td>\n<\/tr>\n
36.<\/td>\nbyte<\/td>\nnextByte(int radix)<\/td>\nScans the next token of the input as a byte.<\/td>\n<\/tr>\n
37.<\/td>\ndouble<\/td>\nnextDouble()<\/td>\nScans the next token of the input as a float.<\/td>\n<\/tr>\n
38.<\/td>\nint<\/td>\nnextInt()<\/td>\nScans the next token of the input as an int.<\/td>\n<\/tr>\n
39.<\/td>\nint<\/td>\nnextInt(int radix)<\/td>\nScans the next token of the input as an int.<\/td>\n<\/tr>\n
40.<\/td>\nString<\/td>\nnextLine()<\/td>\nAdvances this scanner past the current line and returns the input that was skipped.<\/td>\n<\/tr>\n
41.<\/td>\nlong<\/td>\nnextLong()<\/td>\nScans the next token of the input as a long.<\/td>\n<\/tr>\n
42.<\/td>\nlong<\/td>\nnextLong(int radix)<\/td>\nScans the next token of the input as a long.<\/td>\n<\/tr>\n
43.<\/td>\nshort<\/td>\nnextShort()<\/td>\nScans the next token of the input as a short.<\/td>\n<\/tr>\n
44.<\/td>\nshort<\/td>\nnextShort(int radix)<\/td>\nScans the next token of the input as a short.<\/td>\n<\/tr>\n
45.<\/td>\nint<\/td>\nradix()<\/td>\nReturns this scanner’s default radix.<\/td>\n<\/tr>\n
46.<\/td>\nvoid<\/td>\nremove()<\/td>\nThe remove operation is not supported by this implementation of Iterator.<\/td>\n<\/tr>\n
47.<\/td>\nScanner<\/td>\nreset()<\/td>\nResets this scanner.<\/td>\n<\/tr>\n
48.<\/td>\nScanner<\/td>\nskip(Pattern pattern)<\/td>\nSkips input that matches the specified pattern, ignoring delimiters.<\/td>\n<\/tr>\n
49.<\/td>\nScanner<\/td>\nskip(String pattern)<\/td>\nSkips input that matches a pattern constructed from the specified string.<\/td>\n<\/tr>\n
50.<\/td>\nString<\/td>\ntoString()<\/td>\nReturns the string representation of this Scanner.<\/td>\n<\/tr>\n
51.<\/td>\nScanner<\/td>\nuseDelimiter(Pattern pattern)<\/td>\nSets this scanner’s delimiting pattern to the specified pattern.<\/td>\n<\/tr>\n
52.<\/td>\nScanner<\/td>\nuseDelimiter(String pattern)<\/td>\nSets this scanner’s delimiting pattern to a pattern constructed from the specified String.<\/td>\n<\/tr>\n
53.<\/td>\nScanner<\/td>\nuseLocale(Locale locale)<\/td>\nSets this scanner’s locale to the specified locale.<\/td>\n<\/tr>\n
54.<\/td>\nScanner<\/td>\nuseRadix(int radix)<\/td>\nSets this scanner’s default radix to the specified radix.<\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n<\/figure>\n

4. Scanner Java Example<\/h2>\n

Let’s see a Scanner Java Example.

<\/div> <\/div><\/p>\n

JavaUtilScannerExample.java<\/span><\/em><\/p>\n

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package<\/code> com.javacodegeeks.examples;<\/code><\/div>\n
 <\/div>\n
import<\/code> java.util.Scanner;<\/code><\/div>\n
 <\/div>\n
public<\/code> class<\/code> JavaUtilScannerExample {<\/code><\/div>\n
 <\/div>\n
    <\/code>public<\/code> static<\/code> void<\/code> main(String[] args) {<\/code><\/div>\n
        <\/code>\/\/ Create a Scanner object<\/code><\/div>\n
        <\/code>try<\/code> (Scanner scanner = <\/code>new<\/code> Scanner(System.in)) {<\/code><\/div>\n
 <\/div>\n
            <\/code>\/\/ Read values from Console<\/code><\/div>\n
 <\/div>\n
            <\/code>\/\/ A String value<\/code><\/div>\n
            <\/code>System.out.print(<\/code>\"Enter Item Code: \"<\/code>);<\/code><\/div>\n
            <\/code>String itemCode = scanner.next();<\/code><\/div>\n
 <\/div>\n
            <\/code>\/\/ A double value<\/code><\/div>\n
            <\/code>System.out.print(<\/code>\"Enter Price: \"<\/code>);<\/code><\/div>\n
            <\/code>double<\/code> price = scanner.nextDouble();<\/code><\/div>\n
 <\/div>\n
            <\/code>\/\/ An int value<\/code><\/div>\n
            <\/code>System.out.print(<\/code>\"Enter Quantity: \"<\/code>);<\/code><\/div>\n
            <\/code>int<\/code> quantity = scanner.nextInt();<\/code><\/div>\n
 <\/div>\n
            <\/code>\/\/ Display entered values<\/code><\/div>\n
            <\/code>double<\/code> total = price * quantity;<\/code><\/div>\n
            <\/code>System.out.println();<\/code><\/div>\n
            <\/code>System.out.printf(<\/code>\"%d %s @ %f = %f\"<\/code>, quantity, itemCode, price, total);<\/code><\/div>\n
 <\/div>\n
            <\/code>\/\/ Read three int values<\/code><\/div>\n
            <\/code>System.out.printf(<\/code>\"Enter three integer values: \"<\/code>);<\/code><\/div>\n
            <\/code>int<\/code> i1 = scanner.nextInt();<\/code><\/div>\n
            <\/code>int<\/code> i2 = scanner.nextInt();<\/code><\/div>\n
            <\/code>int<\/code> i3 = scanner.nextInt();<\/code><\/div>\n
            <\/code> <\/div>\n
            <\/code>\/\/ Calculate the average and display the result<\/code><\/div>\n
            <\/code>int<\/code> avg = (i1 + i2 + i3) \/ <\/code>3<\/code>;<\/code><\/div>\n
            <\/code> <\/div>\n
            <\/code>System.out.printf(<\/code>\"Average: %d\"<\/code>, avg);<\/code><\/div>\n
        <\/code>} <\/code>catch<\/code> (Exception e) {<\/code><\/div>\n
            <\/code>e.printStackTrace(System.err);<\/code><\/div>\n
        <\/code>}<\/code><\/div>\n
    <\/code>}<\/code><\/div>\n
}<\/code><\/div>\n<\/div>\n<\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n<\/div>\n<\/div>\n

Let\u2019s explain the methods used in the above example.<\/p>\n