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8297288: Example code in Scanner class

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Reviewed-by: lancea, bpb, alanb
This commit is contained in:
Naoto Sato 2022-12-12 17:59:25 +00:00
parent cf93933e21
commit 0267aa528b
1 changed files with 16 additions and 12 deletions

28
src/java.base/share/classes/java/util/Scanner.java

@ -1,5 +1,5 @@
/*
* Copyright (c) 2003, 2021, Oracle and/or its affiliates. All rights reserved.
* Copyright (c) 2003, 2022, Oracle and/or its affiliates. All rights reserved.
* DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
*
* This code is free software; you can redistribute it and/or modify it
@ -51,24 +51,28 @@ import sun.util.locale.provider.ResourceBundleBasedAdapter;
* various {@code next} methods.
*
* <p>For example, this code allows a user to read a number from
* {@code System.in}:
* <blockquote><pre>{@code
* Scanner sc = new Scanner(System.in);
* int i = sc.nextInt();
* }</pre></blockquote>
* the console.
* {@snippet :
* var con = System.console();
* if (con != null) {
* // @link substring="reader()" target="java.io.Console#reader()" :
* Scanner sc = new Scanner(con.reader());
* int i = sc.nextInt();
* }
* }
*
* <p>As another example, this code allows {@code long} types to be
* assigned from entries in a file {@code myNumbers}:
* <blockquote><pre>{@code
* {@snippet :
* Scanner sc = new Scanner(new File("myNumbers"));
* while (sc.hasNextLong()) {
* long aLong = sc.nextLong();
* }
* }</pre></blockquote>
* }
*
* <p>The scanner can also use delimiters other than whitespace. This
* example reads several items in from a string:
* <blockquote><pre>{@code
* {@snippet :
* String input = "1 fish 2 fish red fish blue fish";
* Scanner s = new Scanner(input).useDelimiter("\\s*fish\\s*");
* System.out.println(s.nextInt());
@ -76,7 +80,7 @@ import sun.util.locale.provider.ResourceBundleBasedAdapter;
* System.out.println(s.next());
* System.out.println(s.next());
* s.close();
* }</pre></blockquote>
* }
* <p>
* prints the following output:
* <blockquote><pre>{@code
@ -88,7 +92,7 @@ import sun.util.locale.provider.ResourceBundleBasedAdapter;
*
* <p>The same output can be generated with this code, which uses a regular
* expression to parse all four tokens at once:
* <blockquote><pre>{@code
* {@snippet :
* String input = "1 fish 2 fish red fish blue fish";
* Scanner s = new Scanner(input);
* s.findInLine("(\\d+) fish (\\d+) fish (\\w+) fish (\\w+)");
@ -96,7 +100,7 @@ import sun.util.locale.provider.ResourceBundleBasedAdapter;
* for (int i=1; i<=result.groupCount(); i++)
* System.out.println(result.group(i));
* s.close();
* }</pre></blockquote>
* }
*
* <p>The <a id="default-delimiter">default whitespace delimiter</a> used
* by a scanner is as recognized by {@link Character#isWhitespace(char)