Search for a general sub-string within a string in Java

Question

I am new to Java. I want to ask how to search for a general sub-string within a given string.

For example:-
In the string 12345.67 I want to search for the sub-string .67
And in the string 1.00 I want to search for the string .00.

I basically want to search for the string after the radical (.), provided the number of characters after radical are only 2.

According to my knowledge search for general sub-string is not possible, I thereby asked for your help.

I wish to print the input (stored in the database) , a floating point number, into Indian Currency format, i.e, comma separated.
I even looked at various previous posts but none of them seemed to help me as almost everyone of them failed to produce the requite output for decimal point

`String test = "12345.67"; test = test.substring();` - Try learning about different substring methods and .contains() method. You will find yourself a solution for the problem. — Krishna Prashatt, Jun 22 '18 at 07:17
*"According to my knowledge search for general sub-string is not possible"* what about a regex? — Federico klez Culloca, Jun 22 '18 at 07:17
@ScaryWombat By far I have been looking at various in-built methods definitions to know if searching a general sub-string is possible — Alpha Sniper, Jun 22 '18 at 07:19
@KrishnaPrashatt I tried this approach too but the problem is that there would be about 800-1000 entries and then perform an operation over them. So, I don't know the numbers after the radical point The entry could be somewhat like #### . ## — Alpha Sniper, Jun 22 '18 at 07:22
@AlphaSniper you have answers below, think about accepting one, or comment the best one to explain what how requirement is not exactly answered — azro, Jun 22 '18 at 10:39

azro · Answer 1 · 2018-07-10T12:43:37.193

4

According to my knowledge search for general sub-string is not possible

So you may learn a bit more, here String substring(int beginIndex) method :

String str = "12345.67";
String res = str.substring(str.indexOf('.')); // .67

If you want to check that there is only 2 digits after . :

String str = "12345.67";
String res = str.substring(str.indexOf('.') + 1); // 67
if(res.length() == 2)
    System.out.println("Good, 2 digits");
else
    System.out.println("Holy sh** there isn't 2 digits);

edited Jul 10 '18 at 12:43

answered Jun 22 '18 at 07:19

azro

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@AlphaSniper or `lastIndexOf` in case you have more than one `.` – achAmháin Jun 22 '18 at 07:23

Sunder R · Answer 2 · 2018-06-22T07:25:39.267

1

You can use split plus the substring to achieve your objective

String test = "12345.67";
System.out.println(test.split("\\.")[1].substring(0,2));

In the split function, you can pass the regex with which you could give the separator and in a substring function with the number of characters you want to extract

edited Jun 22 '18 at 07:25

answered Jun 22 '18 at 07:22

Sunder R

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Hi Sunder! Thanks for the reply. Being a novice myself could you please elaborate your code so it's easier for me to understand – Alpha Sniper Jun 22 '18 at 07:24
the substring is not needed and will fail currently. -> `StringIndexOutOfBounds` – Lino Jun 22 '18 at 07:26
since in the question he mentioned that , he want the control over the number of charachters after the radical, substring will help in achieve that. – Sunder R Jun 22 '18 at 07:28

score 0 · Answer 3 · answered Jun 22 '18 at 07:24

Next to the answer provided from @azro you may also use regex:

String string = "12345.67";
Pattern ppattern = Pattern.compile("\\d+(\\.\\d{2})");
Matcher matcher = pattern.matcher(string);
if(matcher.matches()){
   String sub = matcher.group(1);
   System.out.println(sub);
}

Which prints:

.67

score 0 · Answer 4 · answered Jun 22 '18 at 09:00

0

String str = "12345.67";
String searchString = "." + str.split("\\.")[1];
if(str.contains(searchString)){
    System.out.println("The String contains the subString");
}
else{
    System.out.println("The String doesn't contains the subString");
}

answered Jun 22 '18 at 09:00

SriAji

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`str.split("\\.")[1]` will throw if `str` doesn't contain a dot in it – Thomas Ayoub Jun 22 '18 at 10:19
@ThomasAyoub The question was to "search for the string after the radical (.), provided the number of characters after radical are only 2.". That means the string will have a dot. – SriAji Jun 22 '18 at 10:49
I didn't say you were wrong, I just warn about possible error :) – Thomas Ayoub Jun 22 '18 at 12:15

Search for a general sub-string within a string in Java

4 Answers4