I am poor in Regular Expressions. I googled and got basic understanding of it.
I have below requirement: My command may contain some strings with "$(VAR_NAME)" pattern. I need to find out whether it has such type of strings or not. If so, I have to resolve those(I know what should I do, if such strings are there). But, problem is, how to find whether command has strings with "$(VAR_NAME)" pattern. There might be multiple or zero of such string patterns in my command.
As per my knowledge, I have written below code. If I use, 'pattern1'
, in below code, it is matching. But, not with 'pattern'
Can someone help in this?
Thank you in advance.
final String command = "somescript.file $(ABC_PATH1) $(ENV_PATH2) <may be other args too here>";
final String pattern = "\\Q$(\\w+)\\E";
//final String pattern1 = "\\Q$(ABC_PATH1)\\E";
final Pattern pr = Pattern.compile(pattern);
final Matcher match = pr.matcher(command);
if (match.find())
{
System.out.println("Found value: " + match.group(0));
}
else
{
System.out.println("NO MATCH");
}
您可以使用Pattern.quote("Q$(w+)E")
方法添加Pattern以传入编译方法。
final Pattern pr = Pattern.compile(Pattern.quote("Q$(w+)E"));
I think you are overcomplicating the problem.
Since $(
is a reserved "word", just do this to check if there are occurrences:
command.indexOf("$(");
Usage example:
public class Test
{
private static final String[] WORDS;
static {
WORDS = new String[] {
"WORD1",
"WORD2"
};
}
public static void main(final String[] args) {
String command = "somescript.file $(ABC_PATH1) $(ENV_PATH2)";
int index = 0;
int i = 0;
while (true) {
index = command.indexOf("$(", index);
if (index < 0) {
break;
}
command = command.replace(command.substring(index, command.indexOf(")", index) + 1), WORDS[i++]);
}
}
}
It prints: somescript.file WORD1 WORD2
Sticking to the original source:
public class Test
{
public static void main(final String[] args) {
final String command = "somescript.file $(ABC_PATH1) $(ENV_PATH2)";
int index = 0;
int occurrences = 0;
while (true) {
index = command.indexOf("$(", index);
if (index < 0) {
break;
}
occurrences++;
System.out.println(command.substring(index, command.indexOf(")", index++) + 1));
}
if (occurrences < 1) {
System.out.println("No placeholders found");
}
}
}
Using \\Q and \\E will mean you cannot setup a capture group for the variable name because the round brackets will be interpreted literally.
I'd probably do it like this, just escape the outer $, ( and ).
Also if you need multiple matches you need to call find() multiple times, I've used a while loop for this.
final String command = "somescript.file $(ABC_PATH1) $(ENV_PATH2) <may be other args too here>";
final String pattern = "\\$\\((\\w+)\\)";
final Pattern pr = Pattern.compile(pattern);
final Matcher match = pr.matcher(command);
while (match.find()) {
System.out.println("Found value: " + match.group(1));
}
Output
Found value: ABC_PATH1
Found value: ENV_PATH2
The pattern could look like:
public static void main(String[] args) {
final String command = "somescript.file $(ABC_PATH1) $(ENV_PATH2) <may be other args too here>";
final String pattern = "\\$\\((.*?)\\)";
// final String pattern1 = "\\Q$(ABC_PATH1)\\E";
final Pattern pr = Pattern.compile(pattern);
final Matcher match = pr.matcher(command);
while (match.find()) {
System.out.println("Found value: " + match.group(1));
}
}
prints:
Found value: ABC_PATH1
Found value: ENV_PATH2
The problem is that quoting applies to the \\w+ in the pattern as well and I think it was not the intention (as it is, it matches the string "cmd $(\\w+)" that includes the backslash, 'w' and plus sign).
The pattern can be replaced with:
final String pattern = "\\$\\(\\w+\\)";
Or, if you'd still like to use \\Q and \\E on the first part:
final String pattern = "\\Q$(\\E\\w+\\)";
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