Answers for "how to read a string and convert it to a double in java"

string to double java exception

try {
  a = Double.parseDouble(b);
} catch (NumberFormatException e) {
  //the parseDouble failed and you need to handle it here
}

transformer un string en double java

double total = Double.parseDouble(jlbTotal.getText());
double price = Double.parseDouble(jlbPrice.getText());