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Accepted
AlejandroR
Asked: 2022-06-02 03:57:04 +0800 CST 2022-06-02 03:57:04 +0800 CST

How to know if a value is numeric

  • 772

I am doing a validation. I get two strings back, one of them has to be a numeric value less than 10000 and the other string has to have a non-empty String value.

I propose the following:

public boolean validar(String val1, String val2) {
    if(!esNum(gpag) && Integer.parseInt(gpag) > 10000 && q.isEmpty()) {
        return false;
    }else {
        return true;
    }
}
    
public static boolean esNum(String cadena){     
    try{
        if(cadena!= null){
            Integer.parseInt(cadena);
        }
    }catch(NumberFormatException nfe){
         
    }
    return false;
}

Could someone tell me if it is correct or not?

java

2 Answers

  1. Best Answer

    You have some flaws in logic:

    • isNum always returns false.
    • You are calling Integer.parseInttwice, unnecessarily.

    You could do something like:

    public static boolean esNumMenorQue(String cadena, int limite){     
    try {
        //da igual que sea null, se lanzará una NFE
        return Integer.parseInt(cadena) < limite;
    } catch(NumberFormatException nfe){
      //no es un número
    }
    return false; 
}
    • 3

  2. Apart from what @pablo-lozano provided, a small additional suggestion.

    As long as you have this structure in your code

    if (cond) {
    return true;
} else {
    return false;
}

    You can simplify it as

    return cond;

    If we join this recommendation with Pablo's proposal, the validate method would be

    public boolean validar(String val1, String val2) {
    return esNumMenorQue(val1, 10000) && val2 != null && !val2.isEmpty();
}
    • 0