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Java - How to deal with ${param} [duplicate]

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Java generating Strings with placeholders
(12 answers)
Closed 4 years ago.
The client passed me a parameter str = "${param0},${param1}".
I want to replace ${param0} ${param1} with the value I queried from the database.
such as
//str = "${param0},${param1}"
//str = "${param0},${param1}, ${param2}"
//...
public String format(String str) {
String param0 = repository.query0();
//expect
str = "param0,${param1}";
String param1 = repository.query1();
//expect
str = "param0,param1,${param2}";
return str;
}
I know that java.lang.String#replace can solve the problem. But the parameter str is indefinite. It could also be str = "${param0}, ${param1}, ${param2}" or more. Is there any way to satisfy my request?

If you can be confident that it will always be in the format of ${paramX} then you can do the following:
String str = ...;
for (int i = 0; i < results.length; i++)
{
str = str.replace("${param" + i + "}", results[i]);
}
Replace the contents of the for loop and the resutls[i] portion to be however you access the data returned from your query.
If you instead can't dependent on ${paramX} being in sequential order, you can use a more hacky solution by using the following code:
// create a new StringBuilder to reduce concatentation
StringBuilder result = new StringBuilder();
// our warped string input
String str = "${param0}, ${param12}${param1234}${param2}";
// split it anywhere that is formatted with ${paramXXXX}
String[] parts = str.split("\\$\\{param[0-9]{1,}\\}");
// loop through the pieces
for (int i = 0; i < parts.length; i++)
{
// get the parts of the string that are not ${paramXXXX}
result.append(parts[i]);
// the results from the query.
result.append(queryResults[i]); // Replace with the proper way to read your query results
}
The above code should work no matter the input, as long as there are the same number of query results as there are ${paramXXXX} pieces in the input string.
Be sure to replace the code followed by // Replace with ... with the code to read your query results.

Here is an approach using matcher:
String str = "${param0},${param1}, ${param2}";
System.out.println("Matching: "+str);
Pattern regex = Pattern.compile("\\$\\{(\\w+)\\}");
Matcher matcher = regex.matcher(str);
while (matcher.find()){
System.out.println("found: "+matcher.group());
str = matcher.replaceFirst("results");
matcher = regex.matcher(str);
}
System.out.println("Result: "+str);
This is not very efficient, but easy to use. If you have gigabyte-scale computations, consider looping over your input string and compare characters manually.
Update:
Here is a better approach. More efficient and not susceptible for endless loop if results contain the pattern.
String str = "[${param0},${param1}, ${param2}]";
System.out.println("Matching: " + str);
final Pattern regex = Pattern.compile("\\$\\{(\\w+)\\}");
final Matcher matcher = regex.matcher(str);
final StringBuilder sb = new StringBuilder(str.length());
int prevMatch = 0;
while (matcher.find()) {
System.out.println("found: " + matcher.group());
sb.append(str.substring(prevMatch, matcher.start()));
sb.append("results");
prevMatch = matcher.end();
}
sb.append(str.substring(prevMatch, str.length()));
System.out.println("Result: " + sb.toString());

How to get exact match keyword from the given string using java?

I'm trying to match exact AdvanceJava keyword with the given inputText string but it executes both if and else condition,instead of I want only AdvanceJava keyword matched.
String inputText = ("iwanttoknowrelatedtoAdvancejava").toLowerCase().replaceAll("\\s", "");
String match = "java";
List keywordsList = new ArrayList<>();//where keywordsList{advance,core,programming} -> keywordlist fetch
// from database
Enumeration e = Collections.enumeration(keywordsList);
int size = keywordsList.size();
while (e.hasMoreElements()) {
for (int i = 0; i < size; i++) {
String s1 = (String) keywordsList.get(i);
if (inputText.contains(s1) && inputText.contains(match)) {
System.out.println("Yes we providing " + s1);
} else if (!inputText.contains(s1) && inputText.contains(match)) {
System.out.println("Yes we are working on java");
}
}
break;
}
Thanks

you can simply do this by using pattern and matcher classes
Pattern p = Pattern.compile("java");
Matcher m = p.matcher("Print this");
m.find();
If you want to find multiple matches in a line, you can call find() and group() repeatedly to extract them all.

Here's how you can achieve what you seek using pattern matching.
In the first example I have taken your input text as it is. This only improves your algorithm which has O(n^2) performance.
String inputText = ("iwanttoknowrelatedtoAdvancejava").toLowerCase().replaceAll("\\s", "");
String match = "java";
List<String> keywordsList = Arrays.asList("advance", "core", "programming");
for (String keyword : keywordsList) {
Pattern p = Pattern.compile(keyword.concat(match));
Matcher m = p.matcher(inputText);
//System.out.println(m.find());
if (m.find()) {
System.out.println("Yes we are providing " + keyword.concat(match));
}
}
But we can improve this in to a better implementation. Here's a more generic version of the above implementation. This code doesn't manipulate the input text before matching, rather we provide a more generic regular expression which ignores spaces and matches case insensitive manner.
String inputText = "i want to know related to Advance java";
String match = "java";
List<String> keywordsList = Arrays.asList("advance", "core", "programming");
for (String keyword : keywordsList) {
Pattern p = Pattern.compile(MessageFormat.format("(?i)({0}\\s*{1})", keyword, match));
Pattern p1 = Pattern.compile(MessageFormat.format("(?i)({0})", match));
Matcher m = p.matcher(inputText);
Matcher m1 = p1.matcher(inputText);
//System.out.println(m.find());
if(m.find()) {
System.out.println("Yes we are providing " + keyword.concat(match));
} else if(m1.find()) {
System.out.println("Yes we are working with " + match);
}
}

#sithum - Thanks but it executes both condition of if else in output.Please refer Screen shot which I attached here.
I applied following logic and it works fine. please refer it , Thanks.
String inputText = ("iwanttoknowrelatedtoAdvancejava").toLowerCase().replaceAll("\\s", "");
String match = "java";
List<String> keywordsList = session.createSQLQuery("SELECT QUESTIONARIES_RAISED FROM QUERIES").list(); // Fetch values from database (advance,core,programming)
String uniqueKeyword=null;
String commonKeyword= null;
int size =keywordsList.size();
for(int i=0;i<size;i++){
String s1 = (String) keywordsList.get(i);//get values one by one from list
if(inputText.contains(match)){
if(inputText.contains(s1) && inputText.contains(match)){
Queries q1 = new Queries();
q1.setQuestionariesRaised(s1); //set matched keyword to getter setter method
keywordsList1=session.createQuery("from Queries sentence where questionariesRaised='"+q1.getQuestionariesRaised()+"'").list(); // based on matched keyword fetch according to matched keyword sentence which stored in database
for(Queries ob : keywordsList1){
uniqueKeyword= ob.getSentence().toString();// Store fetched sentence to on string variable
}
break;
}else {
commonKeyword= "java only";
}
}
}}
if(uniqueKeyword!= null){
System.out.println("Yes we providing......................" + uniqueKeyword);
}else if(commonKeyword!= null){
System.out.println("Yes we providing " + commonKeyword);
}else{
}

Replace the words in String without using String replace

Is there any solution on how to replace words in string without using String replace?
As you all can see this is like hard coded it. Is there any method to make it dynamically? I heard that there is some library file able to make it dynamically but I am not very sure.
Any expert out there able to give me some solutions? Thank you so much and have a nice day.
for (int i = 0; i < results.size(); ++i) {
// To remove the unwanted words in the query
test = results.toString();
String testresults = test.replace("numFound=2,start=0,docs=[","");
testresults = testresults.replace("numFound=1,start=0,docs=[","");
testresults = testresults.replace("{","");
testresults = testresults.replace("SolrDocument","");
testresults = testresults.replace("numFound=4,start=0,docs=[","");
testresults = testresults.replace("SolrDocument{", "");
testresults = testresults.replace("content=[", "");
testresults = testresults.replace("id=", "");
testresults = testresults.replace("]}]}", "");
testresults = testresults.replace("]}", "");
testresults = testresults.replace("}", "");

In this case, you will need learn regular expression and a built-in String function String.replaceAll() to capture all possible unwanted words.
For example:
test.replaceAll("SolrDocument|id=|content=\\[", "");

Simply create and use a custom String.replace() method which happens to use the String.replace() method within it:
public static String customReplace(String inputString, String replaceWith, String... stringsToReplace) {
if (inputString.equals("")) { return replaceWith; }
if (stringsToReplace.length == 0) { return inputString; }
for (int i = 0; i < stringsToReplace.length; i++) {
inputString = inputString.replace(stringsToReplace[i], replaceWith);
}
return inputString;
}
In the example method above you can supply as many strings as you like to be replaced within the stringsToReplace parameter as long as they are delimited with a comma (,). They will all be replaced with what you supply for the replaceWith parameter.
Here is an example of how it can be used:
String test = "This is a string which contains numFound=2,start=0,docs=[ crap and it may also "
+ "have numFound=1,start=0,docs=[ junk in it along with open curly bracket { and "
+ "the SolrDocument word which might also have ]}]} other crap in there too.";
testResult = customReplace(strg, "", "numFound=2,start=0,docs=[ ", "numFound=1,start=0,docs=[ ",
+ "{ ", "SolrDocument ", "]}]} ");
System.out.println(testResult);
You can also pass a single String Array which contains all your unwanted strings within its elements and pass that array to the stringsToReplace parameter, for example:
String test = "This is a string which contains numFound=2,start=0,docs=[ crap and it may also "
+ "have numFound=1,start=0,docs=[ junk in it along with open curly bracket { and "
+ "the SolrDocument word which might also have ]}]} other crap in there too.";
String[] unwantedStrings = {"numFound=2,start=0,docs=[ ", "numFound=1,start=0,docs=[ ",
"{ ", "SolrDocument ", "]}]} "};
String testResult = customReplace(test, "", unwantedStrings);
System.out.println(testResult);

complex regular expression in Java

I have a rather complex (to me it seems rather complex) problem that I'm using regular expressions in Java for:
I can get any text string that must be of the format:
M:<some text>:D:<either a url or string>:C:<some more text>:Q:<a number>
I started with a regular expression for extracting the text between the M:/:D:/:C:/:Q: as:
String pattern2 = "(M:|:D:|:C:|:Q:.*?)([a-zA-Z_\\.0-9]+)";
And that works fine if the <either a url or string> is just an alphanumeric string. But it all falls apart when the embedded string is a url of the format:
tcp://someurl.something:port
Can anyone help me adjust the above reg exp to extract the text after :D: to be either a url or a alpha-numeric string?
Here's an example:
public static void main(String[] args) {
String name = "M:myString1:D:tcp://someurl.com:8989:C:myString2:Q:1";
boolean matchFound = false;
ArrayList<String> values = new ArrayList<>();
String pattern2 = "(M:|:D:|:C:|:Q:.*?)([a-zA-Z_\\.0-9]+)";
Matcher m3 = Pattern.compile(pattern2).matcher(name);
while (m3.find()) {
matchFound = true;
String m = m3.group(2);
System.out.println("regex found match: " + m);
values.add(m);
}
}
In the above example, my results would be:
myString1
tcp://someurl.com:8989
myString2
1
And note that the Strings can be of variable length, alphanumeric, but allowing some characters (such as the url format with :// and/or . - characters

You mention that the format is constant:
M:<some text>:D:<either a url or string>:C:<some more text>:Q:<a number>
Capture groups can do this for you with the pattern:
"M:(.*):D:(.*):C:(.*):Q:(.*)"
Or you can do a String.split() with a pattern of "M:|:D:|:C:|:Q:". However, the split will return an empty element at the first index. Everything else will follow.
public static void main(String[] args) throws Exception {
System.out.println("Regex: ");
String data = "M:<some text>:D:tcp://someurl.something:port:C:<some more text>:Q:<a number>";
Matcher matcher = Pattern.compile("M:(.*):D:(.*):C:(.*):Q:(.*)").matcher(data);
if (matcher.matches()) {
for (int i = 1; i <= matcher.groupCount(); i++) {
System.out.println(matcher.group(i));
}
}
System.out.println();
System.out.println("String.split(): ");
String[] pieces = data.split("M:|:D:|:C:|:Q:");
for (String piece : pieces) {
System.out.println(piece);
}
}
Results:
Regex:
<some text>
tcp://someurl.something:port
<some more text>
<a number>
String.split():
<some text>
tcp://someurl.something:port
<some more text>
<a number>

To extract the URL/text part you don't need the regular expression. Use
int startPos = input.indexOf(":D:")+":D:".length();
int endPos = input.indexOf(":C:", startPos);
String urlOrText = input.substring(startPos, endPos);

Assuming you need to do some validation along with the parsing:
break the regex into different parts like this:
String m_regex = "[\\w.]+"; //in jsva a . in [] is just a plain dot
String url_regex = "."; //theres a bunch online, pick your favorite.
String d_regex = "(?:" + url_regex + "|\\p{Alnum}+)"; // url or a sequence of alphanumeric characters
String c_regex = "[\\w.]+"; //but i'm assuming you want this to be a bit more strictive. not sure.
String q_regex = "\\d+"; //what sort of number exactly? assuming any string of digits here
String regex = "M:(?<M>" + m_regex + "):"
+ "D:(?<D>" + d_regex + "):"
+ "C:(?<D>" + c_regex + "):"
+ "Q:(?<D>" + q_regex + ")";
Pattern p = Pattern.compile(regex);
Might be a good idea to keep the pattern as a static field somewhere and compile it in a static block so that the temporary regex strings don't overcrowd some class with basically useless fields.
Then you can retrieve each part by its name:
Matcher m = p.matcher( input );
if (m.matches()) {
String m_part = m.group( "M" );
...
String q_part = m.group( "Q" );
}
You can go even a step further by making a RegexGroup interface/objects where each implementing object represents a part of the regex which has a name and the actual regex. Though you definitely lose the simplicity makes it harder to understand it with a quick glance. (I wouldn't do this, just pointing out its possible and has its own benefits)

Replace a set of substring in a string in more efficient way?

I've to replace a set of substrings in a String with another substrings for example
"^t" with "\t"
"^=" with "\u2014"
"^+" with "\u2013"
"^s" with "\u00A0"
"^?" with "."
"^#" with "\\d"
"^$" with "[a-zA-Z]"
So, I've tried with:
String oppip = "pippo^t^# p^+alt^shefhjkhfjkdgfkagfafdjgbcnbch^";
Map<String,String> tokens = new HashMap<String,String>();
tokens.put("^t", "\t");
tokens.put("^=", "\u2014");
tokens.put("^+", "\u2013");
tokens.put("^s", "\u00A0");
tokens.put("^?", ".");
tokens.put("^#", "\\d");
tokens.put("^$", "[a-zA-Z]");
String regexp = "^t|^=|^+|^s|^?|^#|^$";
StringBuffer sb = new StringBuffer();
Pattern p = Pattern.compile(regexp);
Matcher m = p.matcher(oppip);
while (m.find())
m.appendReplacement(sb, tokens.get(m.group()));
m.appendTail(sb);
System.out.println(sb.toString());
But it doesn't work. tokens.get(m.group()) throws an exception.
Any idea why?

You don't have to use a HashMap. Consider using simple arrays, and a loop:
String oppip = "pippo^t^# p^+alt^shefhjkhfjkdgfkagfafdjgbcnbch^";
String[] searchFor =
{"^t", "^=", "^+", "^s", "^?", "^#", "^$"},
replacement =
{"\\t", "\\u2014", "\\u2013", "\\u00A0", ".", "\\d", "[a-zA-Z]"};
for (int i = 0; i < searchFor.length; i++)
oppip = oppip.replace(searchFor[i], replacement[i]);
// Print the result.
System.out.println(oppip);
Here is an online code demo.
For the completeness, you can use a two-dimensional array for a similar approach:
String oppip = "pippo^t^# p^+alt^shefhjkhfjkdgfkagfafdjgbcnbch^";
String[][] tasks =
{
{"^t", "\\t"},
{"^=", "\\u2014"},
{"^+", "\\u2013"},
{"^s", "\\u00A0"},
{"^?", "."},
{"^#", "\\d"},
{"^$", "[a-zA-Z]"}
};
for (String[] replacement : tasks)
oppip = oppip.replace(replacement[0], replacement[1]);
// Print the result.
System.out.println(oppip);

In regex the ^ means "begin-of-text" (or "not" within a character class as negation). You have to place a backslash before it, which becomes two backslashes in a java String.
String regexp = "\\^[t=+s?#$]";
I have reduced it a bit further.