How to check if a string is numeric? [duplicate]

Many options explored at http://www.coderanch.com/t/405258/java/java/String-IsNumeric

One more is

public boolean isNumeric(String s) {  
    return s != null && s.matches("[-+]?\\d*\\.?\\d+");  
}  

Might be overkill but Apache Commons NumberUtils seems to have some helpers as well.

If you are allowed to use third party libraries, suggest the following.

https://commons.apache.org/proper/commons-lang/javadocs/api-2.6/org/apache/commons/lang/math/NumberUtils.html

NumberUtils.isDigits(str:String):boolean
NumberUtils.isNumber(str:String):boolean

Use this

public static boolean isNum(String strNum) {
    boolean ret = true;
    try {

        Double.parseDouble(strNum);

    }catch (NumberFormatException e) {
        ret = false;
    }
    return ret;
}

You can also use ApacheCommons StringUtils.isNumeric - http://commons.apache.org/proper/commons-lang/javadocs/api-2.6/org/apache/commons/lang/StringUtils.html#isNumeric(java.lang.String)

Simple method:

public boolean isBlank(String value) {
    return (value == null || value.equals("") || value.equals("null") || value.trim().equals(""));
}


public boolean isOnlyNumber(String value) {
    boolean ret = false;
    if (!isBlank(value)) {
        ret = value.matches("^[0-9]+$");
    }
    return ret;
}