How to check a string contains only digits and one occurrence of a decimal point?

Question

My idea is something like this but I dont know the correct code

if (mystring.matches(\"[0-9.]+\")){
  //do something here
}else{
  //do something here
}
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Answer 1

You could use indexOf() and lastIndexOf() :

int first = str.indexOf(".");
if ( (first >= 0) && (first - str.lastIndexOf(".")) == 0) {
    // only one decimal point
}
else {
    // no decimal point or more than one decimal point
}