Java 在 ArrayList 中搜索字符串中的某个字符
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Search ArrayList for certain character in string
提问by InDeep
What is the correct syntax for searching an ArrayListof strings for a single character? I want to check each string in the array for a single character.
Ultimately I want to perform multiple search and replaces on all strings in an array based on the presence of a single character in the string.
I have reviewed java-examples.com and java docs as well as several methods of searching ArrayLists. None of them do quite what I need.
P.S. Any pointers on using some sort of file library to perform multiple search and replaces would be great.
搜索ArrayList单个字符的字符串的正确语法是什么？我想检查数组中的每个字符串是否有单个字符。最终，我想根据字符串中单个字符的存在对数组中的所有字符串执行多次搜索和替换。我已经查看了 java-examples.com 和 java 文档以及搜索 ArrayList 的几种方法。他们都没有做我需要的。PS任何关于使用某种文件库来执行多次搜索和替换的指针都会很棒。
--- Edit ---
- - 编辑 - -
As per MightyPork's recommendations arraylistrevised to use simple stringtype. This also made it compatible with hoosssein's solution which is included.
根据 MightyPork 的建议arraylist修改为使用简单string类型。这也使它与包含的 hoosssein 的解决方案兼容。
public void ArrayInput() {
String FileName; // set file variable
FileName = fileName.getText(); // get file name
ArrayList<String> fileContents = new ArrayList<String>(); // create arraylist
try {
BufferedReader reader = new BufferedReader(new FileReader(FileName)); // create reader
String line = null;
while ((line = reader.readLine()) != null) {
if(line.length() > 0) { // don't include blank lines
line = line.trim(); // remove whitespaces
fileContents.add(line); // add to array
}
}
for (String row : fileContents) {
System.out.println(row); // print array to cmd
}
String oldstr;
String newstr;
oldstr = "}";
newstr = "!!!!!";
for(int i = 0; i < fileContents.size(); i++) {
if(fileContents.contains(oldstr)) {
fileContents.set(i, fileContents.get(i).replace(oldstr, newstr));
}
}
for (String row : fileContents) {
System.out.println(row); // print array to cmd
}
// close file
}
catch (IOException ex) { // E.H. for try
JOptionPane.showMessageDialog(null, "File not found. Check name and directory.");
}
}
采纳答案by Hossein Nasr
first you need to iterate the list and search for that character
首先，您需要迭代列表并搜索该字符
string.contains("A");
for replacing the character you need to keep in mind that String is immutable and you must replace new string with old string in that list
要替换字符，您需要记住 String 是不可变的，您必须用该列表中的旧字符串替换新字符串
so the code is like this
所以代码是这样的
public void replace(ArrayList<String> toSearchIn,String oldstr, String newStr ){
for(int i=0;i<toSearchIn.size();i++){
if(toSearchIn.contains(oldstr)){
toSearchIn.set(i, toSearchIn.get(i).replace(oldstr, newStr));
}
}
}
回答by MightyPork
You can try this, modify as needed:
你可以试试这个，根据需要修改：
public static ArrayList<String> findInString(String needle, List<String> haystack) {
ArrayList<String> found = new ArrayList<String>();
for(String s : haystack) {
if(s.contains(needle)) {
found.add(s);
}
}
return found;
}
(to search char, just do myChar+""and you have string)
（要搜索字符，只需执行即可myChar+""获得字符串）
To add the find'n'replace functionality should now be fairly easy for you.
添加 find'n'replace 功能现在对您来说应该相当容易。
Here's a variant for searching String[]:
这是搜索的变体String[]：
public static ArrayList<String[]> findInString(String needle, List<String[]> haystack) {
ArrayList<String[]> found = new ArrayList<String[]>();
for(String fileLines[] : haystack) {
for(String s : fileLines) {
if(s.contains(needle)) {
found.add(fileLines);
break;
}
}
}
return found;
}
回答by arynaq
For the search and replace you are better off using a dictionary, if you know that you will replace Hiwith Hello. The first one is a simple search, here with the index and the string being returned in a Object[2], you will have to cast the result. It returns the first match, you were not clear on this.
对于搜索和替换，最好使用字典，如果您知道将替换Hi为Hello. 第一个是简单的搜索，这里的索引和字符串在 Object[2] 中返回，您必须转换结果。它返回第一场比赛，您对此不清楚。
public static Object[] findStringMatchingCharacter(List<String> list,
char character) {
if (list == null)
return null;
Object[] ret = new Object[2];
for (int i = 0; i < list.size(); i++) {
String s = list.get(i);
if (s.contains("" + character)) {
ret[0] = s;
ret[1] = i;
}
return ret;
}
return null;
}
public static void searchAndReplace(ArrayList<String> original,
Map<String, String> dictionary) {
if (original == null || dictionary == null)
return;
for (int i = 0; i < original.size(); i++) {
String s = original.get(i);
if (dictionary.get(s) != null)
original.set(i, dictionary.get(s));
}
}
回答by Naman
Another way by using iterator
使用迭代器的另一种方式
public static void main(String[] args) {
ArrayList<String> list = new ArrayList<>();
list.add("Naman");
list.add("Aman");
list.add("Nikhil");
list.add("Adarsh");
list.add("Shiva");
list.add("Namit");
Iterator<String> iterator = list.iterator();
while (iterator.hasNext()) {
String next = iterator.next();
if (next.startsWith("Na")) {
System.out.println(next);
}
}
}
回答by Luk
You don't need to iterate over lines twice to do what you need. You can make replacement when iterating over file.
你不需要重复行两次来做你需要的。您可以在迭代文件时进行替换。
Java 8 solution
Java 8 解决方案
try (BufferedReader reader = Files.newBufferedReader(Paths.get("pom.xml"))) {
reader
.lines()
.filter(x -> x.length() > 0)
.map(x -> x.trim())
.map(x -> x.replace("a", "b"))
.forEach(System.out::println);
} catch (IOException e){
//handle exception
}
