时间戳

首页 > 解决方案 > 我的代码中缺少什么？JAVA

java - 我的代码中缺少什么？JAVA

问题描述

这是我的代码块。我正在使用 for 循环遍历字符串，取出一个标记（一个由空格分隔的单词），确定它是否是保留字，如果是，则打印“保留字为：”，否则打印“当前单词是：“。这就是我到目前为止所得到的，我被困在如何使 isKeyWord 工作上。注意：我不能使用拆分功能、扫描仪或标记器。只是一个for循环。

public class Week3Project {
    final static String program = "/*\n" +
" * To change this license header, choose License Headers in Project Properties.\n" +
" * To change this template file, choose Tools | Templates\n" +
" * and open the template in the editor.\n" +
" */\n" +
"package testapplication2;\n" +
"\n" +
"import java.util.Scanner;\n" +
"\n" +
"/**\n" +
" *\n" +
" * @author james\n" +
" */\n" +
"public class TestApplication2 {\n" +
"\n" +
"    /**\n" +
"     * @param args the command line arguments\n" +
"     */\n" +
"    public static void main(String[] args) {\n" +
"        Scanner input = new Scanner(System.in);\n" +
"        \n" +
"        System.out.println(\"Enter integer #1\");\n" +
"        int num1 = input.nextInt();\n" +
"        \n" +
"        System.out.println(\"Enter integer #2\");\n" +
"        int num2 = input.nextInt();\n" +
"        \n" +
"        System.out.println(\"Enter integer #3\");\n" +
"        int num3 = input.nextInt();\n" +
"        \n" +
"        System.out.println(\"Enter integer #4\");\n" +
"        int num4 = input.nextInt();\n" +
"        \n" +
"        System.out.println(\"Enter integer #5\");\n" +
"        int num5 = input.nextInt();\n" +
"        \n" +
"        //determine the sum\n" +
"        int sum = num1 + num2 + num3 + num4 + num5;\n" +
"        \n" +
"        //this is helpful to make sure your sum is correct\n" +
"        System.out.println(\"The sum is: \" + sum);\n" +
"        \n" +
"        //why doesn't this generate the sum correctly\n" +
"        double average = sum / 5;\n" +
"        \n" +
"        //The average, lets hope its right...\n" +
"        System.out.println(\"The average of your numbers is: \" + average);\n" +
"        \n" +
"    }\n" +
"    \n" +
"}\n" +
"";


    public static void main(String[] args)
    {
        String str = program;

        String s = "";
        String[] keywords = {"abstract", "assert", "boolean", "break", "byte", "case", "catch", "char", "class", "const", "continue", "default", "do", "double", "else", "enum",
 "extends", "final", "finally", "float", "for", "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"};
        for (int i = 0; i < str.length(); i++) {
            s += str.charAt(i) + "";
            if (str.charAt(i) == ' ' || str.charAt(i) == '\t' || str.charAt(i) == '\n') {
                String currentWord = s.toString();
                //System.out.println(currentWord);                
                boolean isKeyWord = false; 
                for (int j = 0; j < keywords.length; j++) { 
                    if (currentWord.equalsIgnoreCase(keywords[j])) { 
                        isKeyWord = true;
                    }
                } break; } }
                if (isKeyWord == true) {
                    System.out.println("Reserved word is: ["  + currentWord + "]");
                }
                else {
                    System.out.println("Current word is: [" + currentWord + "]")
                }
                s = "";//Clear the string to get it ready to build next token.


            }
        }

标签： javastring

解决方案

    for (int i = 0; i < str.length(); i++) {
        if (str.charAt(i) == ' ' || str.charAt(i) == '\t' || str.charAt(i) == '\n') {
            // end of token, check if key word
            String currentWord = s.toString();     
            boolean isKeyword = false       
            for (int j = 0; j < keywords.length; j++) { 
                if (currentWord.equalsIgnoreCase(keywords[j])) { 
                    isKeyword = true;
                    break;
                } 
            }
            if(isKeyword) {
                System.out.println("Reserved word is: ["  + currentWord + "]");
            } else {
                System.out.println("Current word is: [" + currentWord + "]");
            }
            s = "";//Clear the string to get it ready to build next token.
        } else {
            // continue building token
            s += str.charAt(i) + "";
        }
    }

您的循环版本在检查之前会附加空格/制表符/换行符，这会导致当前单词永远不会与您的关键字匹配。

推荐阅读