[英]matching string array content with regular expression java
i am new to java. 我是Java新手。 i am trying to use java regular expression to compare two string arrays containing names and then use a nested for loop to print out the names that have a match and names that don't have a match. 我正在尝试使用Java正则表达式比较包含名称的两个字符串数组,然后使用嵌套的for循环打印出具有匹配项的名称和不具有匹配项的名称。 below is my code 下面是我的代码
public class Main {
public static void main(String[] args) {
// write your code here
String regex;
Pattern pattern;
String stringToBeMatched;
Matcher matcher;
boolean b;
String [] names1 = {"Peter","Harry","Potter","Mary","Jerry"};
String [] names2 = {"Adam","Jerry","Potter","Martin","Chris", "Rose"};
//try a loop with two variables for loop
for (int x=0;x >= names2.length;x++) {
regex = names2[x];
pattern = Pattern.compile(regex);
for(int y = 0; y >= names1.length; y++){
stringToBeMatched = names1[y];
matcher = pattern.matcher(stringToBeMatched);
b = matcher.find();
if (b) {System.out.println(names1[y] +" has a match");}
else{System.out.println(names1[y] +" has no match");}
}
}
}
}
the code executes and returns the output Process finished with exit code 0
without displaying any message specified by any of the System.out.println()
statements. 该代码将执行并返回Process finished with exit code 0
结尾的输出Process finished with exit code 0
而不会显示任何System.out.println()
语句指定的消息。 please guys, what am i not doing right? 拜托,我在做什么不对?
Unless I am misunderstanding your intentions, you should not use Regex here. 除非我误解了您的意图,否则您不应在此处使用Regex。 My understanding is you want to compare two arrays for duplicate elements. 我的理解是您想比较两个数组中重复的元素。
You have your arrays: 您有数组:
String[] names1 = {"Peter", "Harry", "Potter", "Mary", "Jerry"};
String[] names2 = {"Adam", "Jerry", "Potter", "Martin", "Chris", "Rose"};
Method 1 - nested for loops. 方法1-嵌套循环。
for(int i = 0; i < names1.length; i++) {
for(int j = 0; j < names2.length; j++) {
if(names1[i].equals(names2[j])) System.out.println(names1[i] + " is in both arrays.");
}
}
Method 2 - nested foreach loops. 方法2-嵌套的foreach循环。
for(String name1 : names1) {
for(String name2 : names2) {
if(name1.equals(name2)) System.out.println(name1 + " is in both arrays.");
}
}
Method 3 - using a List . 方法3-使用列表 。
List<String> names2List = Arrays.asList(names2);
for(String name1 : names1) {
if(names2List.contains(name1)) System.out.println(name1 + " is in both arrays.");
}
Method 4 - using a Set . 方法4-使用Set 。 This works because HashSet#add() will NOT add duplicates, and returns false if requested. 之所以可行,是因为HashSet#add()不会添加重复项,如果需要,则返回false。
Set<String> names2Set = new HashSet<>(Arrays.asList(names2));
for(String name1 : names1) {
if(!names2Set.add(name1)) System.out.println(name1 + " is in both arrays.");
}
Method 5 - using Streams . 方法5-使用流 。 If you want to get fancy. 如果你想得到幻想。
for(String name1 : names1) {
if(Arrays.stream(names2).anyMatch(name1::equals)) System.out.println(name1 + " is in both arrays.");
}
With lambda functions use "distinct" to not print duplicate values. 对于lambda函数,请使用“ distinct”不打印重复值。
String [] names1 = {"Peter","Harry","Potter","Mary","Jerry"};
String [] names2 = {"Adam","Jerry","Potter","Martin","Chris", "Rose", "Peter", "Peter"};
for (String name1:
names1) {
Arrays.stream(names2).filter(name1::equals).distinct().forEach(System.out::println);
}
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