Is there a short hand for if(s != null && !s.isEmpty())

Question

There are many != null s and != null && !s.isEmpty()

Like this:

if(sidebar.getModel() != null && !sidebar.getModel().isEmpty()) { ... }

In our code. Too many that it looks not really good. Is there a short hand for this null check. Which Java library provides extensive support for such shorthand functions while does not need that much dependency on other java artifacts?

Like if(notNull(s)) or if(notEmpty(s)) which checks for not null and not empty altogether. Something like this.

If these sort of checks are everywhere in your code, you might benefit from reading http://stackoverflow.com/questions/271526/avoiding-null-statements-in-java?rq=1 — Misha, Apr 03 '15 at 08:48

score 1 · Accepted Answer · answered Apr 03 '15 at 08:37

1

For String class there is StringUtils.isEmpty(String value) in apache-commons-lang3. For other types you can create your own static method and use it via static import.

answered Apr 03 '15 at 08:37

Andremoniy

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Also for strings: "".equals(inputString) will do both a null check and an empty check. – Pieter De Bie Apr 03 '15 at 08:40
2

@PieterDeBie but it returns false if String is null – rzysia Apr 03 '15 at 08:43
@PieterDeBie what? and if `"".equals("")` return `true`, while it is really empty value – Andremoniy Apr 03 '15 at 08:43
Indeed, I was wrong (I don't use that construction too much since i hate yoda statements). You can use it to check for strings without having to worry for null strings. – Pieter De Bie Apr 03 '15 at 08:47

score 1 · Answer 2 · answered Apr 03 '15 at 08:50

Apache commons-lang

Checks if a String is not empty (""), not null and not whitespace only.

StringUtils.isNotBlank(null)      = false
StringUtils.isNotBlank("")        = false
StringUtils.isNotBlank(" ")       = false
StringUtils.isNotBlank("bob")     = true
StringUtils.isNotBlank("  bob  ") = true

Parameters: str - the String to check, may be null

Returns: true if the String is not empty and not null and not whitespace

catch23 · Answer 3 · 2015-04-03T08:59:41.183

From Java 1.7 you can use utility class Objects:

Checks that the specified object reference is not null. This method is designed primarily for doing parameter validation in methods and constructors, as demonstrated below:

 public Foo(Bar bar) {
     this.bar = Objects.requireNonNull(bar);
 }

Useful links:

UPDATE:

For avoiding NullPointerException Java 1.8 has some special class Optional.

Working with this class will be smt as follows:

    String contents = new String(Files.readAllBytes(Paths.get(Test.ALICE_PATH)), StandardCharsets.UTF_8);
    List<String> wordList = Arrays.asList(contents.split("[\\P{L}]+"));

    Optional<String> optionalValue = wordList.stream().filter(s -> s.contains("red")).findFirst();
    optionalValue.ifPresent(s -> System.out.println(s + " contains red"));

    Set<String> results = new HashSet<>();
    optionalValue.ifPresent(results::add);
    Optional<Boolean> added = optionalValue.map(results::add);

    System.out.println(added);
    //
    Optional<String> optionalString = Optional.empty();
    String result = optionalString.orElse("N/A");
    System.out.println("result: " + result);

    result = optionalString.orElseGet(() -> System.getProperty("user.dir"));
    System.out.println("result: " + result);

It is very bad decision: it will throw `NullPointerException` if value is null. Not what really QA wants — Andremoniy, Apr 03 '15 at 08:45
This will throw an exception if the object is null. That's not what the questioner wants. It seems that these methods should be used for validation of parameters. — Mehul Lalan, Apr 03 '15 at 08:46

Is there a short hand for if(s != null && !s.isEmpty())

3 Answers3