CODEWITHSUNDEEP
javaguava
Spring
Spring

Reputation: 11835

Get empty string when null

I want to get string values of my fields (they can be type of long string or any object),

if a field is null then it should return empty string, I did this with guava;

nullToEmpty(String.valueOf(gearBox))
nullToEmpty(String.valueOf(id))
...

But this returns null if gearbox is null! Not empty string because valueOf methdod returns string "null" which leads to errors.

Any Ideas?

EDIt: there are 100s fields I look for something easy to implement

Upvotes: 119

Views: 202602

Answers (9)

Flavian-Calinic Stuparu
Flavian-Calinic Stuparu

Reputation: 17

This should do the trick: "" + gearBox

Upvotes: 0

Akshay Sardhara
Akshay Sardhara

Reputation: 178

StringUtils.defaultString(String str) Returns either the passed in String, or if the String is null, an empty String ("").

Example from java doc

StringUtils.defaultString(null) will return "" StringUtils.defaultString("") will return "" StringUtils.defaultString("bat") will return "bat"

Upvotes: 14

Ari Singh
Ari Singh

Reputation: 1306

In Java 9+ use : Objects.requireNonNullElse (obj, defaultObj) https://docs.oracle.com/javase/9/docs/api/java/util/Objects.html#requireNonNullElse-T-T-

//-- returns empty string if obj is null
Objects.requireNonNullElse (obj, "")

Upvotes: 6

Won-Sik Kim
Won-Sik Kim

Reputation: 431

If alternative way, Guava provides Strings.nullToEmpty(String).

Source code

String str = null;
str = Strings.nullToEmpty(str);
System.out.println("String length : " + str.length());

Result

0

Upvotes: 25

Federico Piazza
Federico Piazza

Reputation: 31035

For java 8 you can use Optional approach:

Optional.ofNullable(gearBox).orElse("");
Optional.ofNullable(id).orElse("");

Upvotes: 71

renke
renke

Reputation: 1230

Since you're using guava:

Objects.firstNonNull(gearBox, "").toString();

Upvotes: 6

Keppil
Keppil

Reputation: 46219

If you don't mind using Apache commons, they have a StringUtils.defaultString(String str) that does this.

Returns either the passed in String, or if the String is null, an empty String ("").

If you also want to get rid of "null", you can do: 

StringUtils.defaultString(str).replaceAll("^null$", "")

or to ignore case: 

StringUtils.defaultString(str).replaceAll("^(?i)null$", "")

Upvotes: 38

arshajii
arshajii

Reputation: 129517

You can use Objects.toString() (standard in Java 7):

Objects.toString(gearBox, "")

Objects.toString(id, "")

From the linked documentation:

public static String toString(Object o, String nullDefault)

Returns the result of calling toString on the first argument if the first argument is not null and returns the second argument otherwise.

Parameters:
o - an object
nullDefault - string to return if the first argument is null

Returns:
the result of calling toString on the first argument if it is not null and the second argument otherwise.

See Also:
toString(Object)

Upvotes: 258

Samhain
Samhain

Reputation: 1765

Use an inline null check

gearBox == null ? "" : String.valueOf(gearBox);

Upvotes: 10

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