Checking if a string contains a dot

Question

Today I was trying to detect if a string contains a dot, but my code isn't working

 String s = "test.test";
 if(s.contains("\\.")) {
     System.out.printLn("string contains dot");
 }

Answer 1

contains() method of String class does not take regular expression as a parameter, it takes normal text.

String s = "test.test";

if(s.contains("."))
{
    System.out.println("string contains dot");
}

Answer 2

String#contains receives a plain CharacterSequence eg a String , not a regex. Remove the \\\\ from there.

String s = "test.test";
if (s.contains(".")) {
    System.out.println("string contains dot");
}

Answer 3

你只需要

s.contains (".");

Answer 4

Sometimes you will need to find a character and do something with it, a similar check can also be done using .indexOf('.') , for instance:

"Mr. Anderson".indexOf('.'); // will return 2

The method will return the index position of the dot, if the character doesn't exist, the method will return -1, you can later do a check on that.

if ((index = str.indexOf('.'))>-1) { .. do something with index.. }

Answer 5

The easiest way is to check with a .contains() statement.

Note: .contains() works only for strings.

From

 String s = "test.test";
 if(s.contains("\\.")) {
     System.out.printLn("string contains dot");
 }

To

String s = "test.test";
 if(s.contains(".")) {
     System.out.printLn("string contains dot");
 }

Do like this to check any symbol or character in a string.

Answer 6

Try this,

String k="test.test";
    String pattern="\\.";
    Pattern p=Pattern.compile(pattern);
    Matcher m=p.matcher(k);
    if(m.find()){
        System.out.println("Contains a dot");
    }
}