Java中满足匹配条件时如何终止多个非嵌套for循环

你现有代码的问题是break只会终止当前所在的单层循环，所以第一个数组查到匹配项后，后面三个数组的循环还是会依次执行，以下是两种可直接落地的实现方案：

方案1：新增匹配状态标记 #

新增布尔变量标记是否已经找到匹配项，每个数组遍历前先判断状态，未找到才执行遍历：

import java.io.IOException;
import java.nio.charset.StandardCharsets;
import java.nio.file.Files;
import java.nio.file.Paths;
import java.util.regex.Matcher;
import java.util.regex.Pattern;

public class practice {

    static String wfound;

    public static void main(String[] args) throws IOException {
        String a[] = { "universe", "world", "html" ,"name"};
        String b[] = { "animal", "Bird", "HTML" };
        String c[] = { "choclate", "HTML", "hello" };
        String d[] = { "css", "side"};

        String file= new String(Files.readAllBytes(Paths.get("D://test1.txt")), StandardCharsets.UTF_8);
        // 新增匹配状态标记，默认未找到
        boolean hasFound = false;

        for (String an : a) {
            Pattern p = Pattern.compile("\\b" + an + "\\b", Pattern.CASE_INSENSITIVE);
            Matcher m = p.matcher(file);
            if (m.find()) {
                wfound = an;
                System.out.println("In array 1: " + an);
                hasFound = true;
                break;
            }
        }
        // 只有未找到才执行下一个数组的遍历
        if (!hasFound) {
            for (String ab : b) {
                Pattern p = Pattern.compile("\\b" + ab + "\\b", Pattern.CASE_INSENSITIVE);
                Matcher m = p.matcher(file);
                if (m.find()) {
                    wfound = ab;
                    System.out.println("In array 2: " + ab);
                    hasFound = true;
                    break;
                }
            }
        }
        if (!hasFound) {
            for (String ac : c) {
                Pattern p = Pattern.compile("\\b" + ac + "\\b", Pattern.CASE_INSENSITIVE);
                Matcher m = p.matcher(file);
                if (m.find()) {
                    wfound = ac;
                    System.out.println("In array 3: " + ac);
                    hasFound = true;
                    break;
                }
            }
        }
        if (!hasFound) {
            for (String ad : d) {
                Pattern p = Pattern.compile("\\b" + ad + "\\b", Pattern.CASE_INSENSITIVE);
                Matcher m = p.matcher(file);
                if (m.find()) {
                    wfound = ad;
                    System.out.println("In array 4: " + ad);
                    hasFound = true;
                    break;
                }
            }
        }
    }
}

方案2：优化重复代码+标签跳出 #

四个数组的遍历逻辑完全一致，可以把它们打包成二维数组统一遍历，配合Java的带标签break直接跳出外层循环，代码更简洁易维护：

import java.io.IOException;
import java.nio.charset.StandardCharsets;
import java.nio.file.Files;
import java.nio.file.Paths;
import java.util.regex.Matcher;
import java.util.regex.Pattern;

public class practice {

    static String wfound;

    public static void main(String[] args) throws IOException {
        String a[] = { "universe", "world", "html" ,"name"};
        String b[] = { "animal", "Bird", "HTML" };
        String c[] = { "choclate", "HTML", "hello" };
        String d[] = { "css", "side"};
        // 把四个数组按优先级打包成二维数组
        String[][] allKeywords = {a, b, c, d};

        String file= new String(Files.readAllBytes(Paths.get("D://test1.txt")), StandardCharsets.UTF_8);

        // 给外层循环加标签
        search:
        for (int i = 0; i < allKeywords.length; i++) {
            String[] currentArr = allKeywords[i];
            for (String keyword : currentArr) {
                Pattern p = Pattern.compile("\\b" + keyword + "\\b", Pattern.CASE_INSENSITIVE);
                Matcher m = p.matcher(file);
                if (m.find()) {
                    wfound = keyword;
                    System.out.println("In array " + (i+1) + ": " + keyword);
                    // 直接跳出外层的search循环，所有遍历直接终止
                    break search;
                }
            }
        }
    }
}

后续如果新增关键词数组只要往allKeywords里追加即可，不用重复写循环逻辑。

内容的提问来源于stack exchange，提问作者john