.isBlank() Not Recognized in Java NetBeans

Question

I tried implementing .isBlank() to omit whitespace. The netBeans IDE 11.0 (and 8.2) shows "cannot find symbol" error.

When this project is opened from another PC it works!

public FormulaElement parseFormula(String text) {

        StringTokenizer tokenizer = new StringTokenizer(text, "+-*/^√()!πe% \t", true);

        Vector<Object> vec = new Vector<>();
        while (tokenizer.hasMoreTokens()){
        String temp= tokenizer.nextToken();
        //omitting whitespace
        if(temp.isBlank() == true){
           continue;
        }

How can I fix the issue?

Which Java version are you using? `isBlank()` is available on `String` only in java 11+ — ernest_k, Jul 21 '19 at 04:48
when I run Java -version on CMD it shows, java version "1.8.0_221" Java(TM) SE Runtime Environment (build 1.8.0_221-b11) Java HotSpot(TM) 64-Bit Server VM (build 25.221-b11, mixed mode) — Abheeth Kotelawala, Jul 21 '19 at 04:50
With java 8, You can use like temp==null || temp.isEmpty(). Another way temp==null || temp.length()=0 — prasingh, Jul 21 '19 at 05:04
@prasingh rather `temp==null || temp.trim().isEmpty()` (if you don't `trim`, it will return `false` if the string contains blanks) — ernest_k, Jul 21 '19 at 05:06

score 5 · Accepted Answer · edited Jul 21 '19 at 05:28

To collect all the comments and putting some additional information. Here we are:

JDK 11

String class have isBlank() for checking blank string.

Less then JDK 11

There is no built in function. We have to tackle it is different way.

First check whether the string is null
If it is not null then Trim the string and check its length

Example:

temp == null || temp.trim().length() == 0
or, temp == null || temp.trim().isEmpty(). Note: is empty is internally checking length

Apart from this, there are some 3rd party Libs available that do this for us Like,

Apache common lang

It has various method for String. For our case StringUtils.isBlank is suitable candidate. I recommend you to read other string related methods too.

Guava

This lib also provide methods for string.

Example: Strings.isNullOrEmpty()

.isBlank() Not Recognized in Java NetBeans

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