String[] keywords = {"abstract", "assert", "boolean", "break", "byte", "case", "catch", "char", "class", "const", "continue", "default", "do", "double", "else", "enum", "extends", "for", "final", "finally", "float", "goto", "if", "implements", "import", "instanceof", "int", "interface", "long", "native", "new", "package", "private", "protected", "public", "return", "short", "static", "strictfp", "super", "switch", "synchronized", "this", "throw", "throws", "transient", "try", "void", "volatile", "while", "true", "false", "null"}; Map<String, Integer> keywordCount = new TreeMap<>();请分析这段代码

这段代码定义了一个字符串数组`keywords`，其中存储了Java中的关键字。接着，定义了一个`Map`对象`keywordCount`，用来存储关键字与其出现次数的对应关系。这里使用了`TreeMap`作为`Map`的实现，所以关键字会按照字典序排序。

可以通过以下代码统计`keywords`中每个关键字出现的次数，并将结果存储在`keywordCount`中：

for (String keyword : keywords) {
    if (keywordCount.containsKey(keyword)) {
        keywordCount.put(keyword, keywordCount.get(keyword) + 1);
    } else {
        keywordCount.put(keyword, 1);
    }
}

遍历`keywords`数组中的每个元素，如果`keyword`已经在`keywordCount`中出现过，则将其出现次数加1；否则将其出现次数设为1并将其存入`keywordCount`中。最终，`keywordCount`中存储了每个关键字与其出现次数的对应关系。

相关问题

我是Java语言的初学者，请帮我写一个Java代码，来判断下列哪些标识符是合法的？那些是Java语言的关键字？apps,class,applet,Applet,a++,5#Y,hint++,--hint,$56,#67,public,width

在Java中，合法的标识符必须满足以下几个规则：

1. 只能包含字母、数字、下划线(_)和美元符号($)。
2. 首字符不能是数字。
3. 关键字不能作为标识符。

以下是Java关键字列表，它们不能作为变量名或标识符：

final, static, true, false, null, abstract, class, default, package, super, if, else, for, goto, break, continue, while, do, switch, case, default, throw, throws, try, catch, instanceof, this, return, void, const, volatile, transient, synchronized, strictfp, import, public, private, protected, enum, byte, short, int, long, float, double, char, boolean, String

根据这些规则，我们可以编写一个简单的Java程序来判断给定的标识符是否合法以及是否是关键字：

import java.util.HashSet;
import java.util.Set;

public class IdentifierChecker {
    // 关键字集合
    private static final Set<String> KEYWORDS = new HashSet<>(Arrays.asList(
            "abstract", "assert", "boolean", "break", "byte", ...)); // 全部关键字

    public static void main(String[] args) {
        String[] identifiers = {"apps", "class", "applet", "Applet", "a++", "5#Y", "hint++", "--hint", "$56", "#67",
                "public", "width"};

        for (String identifier : identifiers) {
            System.out.println("Identifier: " + identifier);
            if (KEYWORDS.contains(identifier)) {
                System.out.println("- It's a keyword: " + identifier);
            } else {
                if (isValidIdentifier(identifier)) {
                    System.out.println("- It's a valid identifier.");
                } else {
                    System.out.println("- It's not a valid identifier because it violates naming rules.");
                }
            }
        }
    }

    /**
     * 检查标识符是否符合Java命名规范
     */
    private static boolean isValidIdentifier(String identifier) {
        return identifier.matches("[a-zA-Z_$][a-zA-Z0-9_$]*");
    }
}

运行上述代码，你会看到每个标识符的判断结果。

如下的代码如何输入//Test public method public HashMap(int initialCapacity) { this(initialCapacity, DEFAULT_LOAD_FACTOR); } public HashMap(int initialCapacity, float loadFactor) { if (initialCapacity < 0) throw new IllegalArgumentException("Illegal initial capacity: " + initialCapacity); if (initialCapacity > MAXIMUM_CAPACITY) initialCapacity = MAXIMUM_CAPACITY; if (loadFactor <= 0 || Float.isNaN(loadFactor)) throw new IllegalArgumentException("Illegal load factor: " + loadFactor); this.loadFactor = loadFactor; this.threshold = tableSizeFor(initialCapacity); } exit

你可以使用以下Java代码来读入这段源码：

import java.util.Scanner;

public class Main {
    public static void main(String[] args) {
        Scanner scanner = new Scanner(System.in);

        // 读入源码
        System.out.println("请输入源码：");
        String sourceCode = "";
        String line;
        while (!(line = scanner.nextLine()).equals("exit")) {
            sourceCode += line + "\n";
        }

        // 统计关键字数量
        String[] keywords = {"abstract", "assert", "boolean", "break", "byte", "case", "catch", "char", "class", "const",
            "continue", "default", "do", "double", "else", "enum", "extends", "false", "final", "finally", "float",
            "for", "goto", "if", "implements", "import", "instanceof", "int", "interface", "long", "native", "new",
            "null", "package", "private", "protected", "public", "return", "short", "static", "strictfp", "super",
            "switch", "synchronized", "this", "throw", "throws", "transient", "true", "try", "void", "volatile", "while"};

        int count = 0;
        for (String word : sourceCode.split("\\W+")) {
            if (word.isEmpty()) {
                continue;
            }
            for (String keyword : keywords) {
                if (word.equals(keyword)) {
                    count++;
                    break;
                }
            }
        }

        // 输出关键字数量
        System.out.println("源码中关键字的数量为：" + count);
    }
}

该程序会读入从键盘输入的源码，输入完毕后输入“exit”即可停止输入。程序会统计源码中Java关键字的数量，并输出这个数量。请注意，该程序只是一个简单的演示，实际应用中可能需要更为复杂的处理方式。