Core Java

Java String trim() method with Example

Photo of Mary Zheng Mary ZhengFebruary 26th, 2019Last Updated: September 28th, 2020
0 267 9 minutes read

In this post, we feature a comprehensive article about the Java String trim() method with Examples.

1. Introduction

The java.lang.String class represents character strings. It provides a trim() method since version 1.4 to return a new string object whose value is the copy of the original string without any leading or trailing white-space.

Note: a white-space is when the ASCII code of the character is less than or equal to the space character, which is \u0020.

Here is the method syntax:

public String trim()

In this example, I will demonstrate how to trim a string in three ways:

  • Create a Function to trim a string in JDK 8 or higher version
  • Invoke trim for a non-null String object
  • Invoke trim for an Optional String object

2. Technologies Used

The example code in this article was built and run using:

  • Java 1.8.101
  • Maven 3.3.9
  • Eclipse Oxygen
  • JUnit 4.12
  • H2
  • Spring

3. Maven Project

I will create a Maven project via the Spring starter tool. Enter the group and artifact values and click the Generate Project button. A maven project will be generated and downloaded to your workstation. Import it into your Eclipse work space.

3.1 Dependency

Add H2 dependency to pom.xml.

pom.xml

<?xml version="1.0" encoding="UTF-8"?>
<project xmlns="http://maven.apache.org/POM/4.0.0" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
	xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsd">
	<modelVersion>4.0.0</modelVersion>

	<groupId>jcg.zheng.demo</groupId>
	<artifactId>spring-string-trim-demo</artifactId>
	<version>0.0.1-SNAPSHOT</version>
	<packaging>jar</packaging>

	<name>spring-jparepository-demo</name>
	<description>Demo Spring Data JPA Application</description>

	<parent>
		<groupId>org.springframework.boot</groupId>
		<artifactId>spring-boot-starter-parent</artifactId>
		<version>1.5.10.RELEASE</version>
		<relativePath /> <!-- lookup parent from repository -->
	</parent>

	<properties>
		<project.build.sourceEncoding>UTF-8</project.build.sourceEncoding>
		<project.reporting.outputEncoding>UTF-8</project.reporting.outputEncoding>
		<java.version>1.8</java.version>	
	</properties>

	<dependencies>		

		<dependency>
			<groupId>org.springframework.boot</groupId>
			<artifactId>spring-boot-starter-data-jpa</artifactId>
		</dependency>

		<dependency>
			<groupId>com.h2database</groupId>
			<artifactId>h2</artifactId>
			<scope>runtime</scope>
		</dependency>

		<dependency>
			<groupId>org.springframework.boot</groupId>
			<artifactId>spring-boot-starter-test</artifactId>
			<scope>test</scope>
		</dependency>
	</dependencies>


	<build>
		<plugins>
			<plugin>
				<groupId>org.springframework.boot</groupId>
				<artifactId>spring-boot-maven-plugin</artifactId>
			</plugin>
		</plugins>
	</build>
</project>

3.2 Spring Boot Application

I will save contacts into a H2 database table via Spring JpaRepositories. You just need to add @EnableJpaRepositories to the generated DemoApplication.java file.

DemoApplication.java

package jcg.zheng.demo;

import org.springframework.boot.SpringApplication;
import org.springframework.boot.autoconfigure.SpringBootApplication;
import org.springframework.data.jpa.repository.config.EnableJpaRepositories;

@SpringBootApplication
@EnableJpaRepositories(basePackages = "jcg.zheng.demo")
public class DemoApplication {

	public static void main(String[] args) {
		SpringApplication.run(DemoApplication.class, args);
	}

}

3.3 Application Properties

Spring boot will configure a H2 data source based on the values in application.properties.

application.properties

spring.datasource.url=jdbc:h2:file:~/main-source;AUTO_SERVER=TRUE
spring.datasource.username=sa
spring.datasource.password=
spring.datasource.driver-class-name=org.h2.Driver

4. Contact

In this step, I will create a contact class that maps to a database table. It has several data members: id, first name, last name, and a title (optional). The Contact(String, String) constructor uses setFirstName and setLastName to set the first name and last name with trimmed values.

Here are setters that trim a string in three ways:

  • setLastName – it first creates a Java 8 Function to trim a string with a method reference and then uses its apply method to set the last name value. Click my other article for details about Java 8 Function.
  • setFirstName – it calls the trim method on the first name.
  • setTitle – it invokes the trim method if a title exists.

Contact.java

package jcg.zheng.demo.entity;

import java.util.Optional;
import java.util.function.Function;

import javax.persistence.Entity;
import javax.persistence.GeneratedValue;
import javax.persistence.Id;
import javax.persistence.Transient;

import org.springframework.util.StringUtils;


@Entity
public class Contact {

    @Id
    @GeneratedValue
    private Long id;

    private String firstName;

    private String lastName;

    @Transient
    private Optional<String> title;

    public Contact(String firstName, String lastName) {
        if (StringUtils.isEmpty(firstName) || StringUtils.isEmpty(lastName)) {
            throw new IllegalArgumentException("Require both firstName and lastName");
        }
        setFirstName(firstName);
        setLastName(lastName);
    }

    public Long getId() {
        return id;
    }

    public String getFirstName() {
        return firstName;
    }

    public void setFirstName(String firstName) {
        this.firstName = firstName.trim();
    }

    public String getLastName() {
        return lastName;
    }

    public void setLastName(String lastName) {
        Function<String, String> trimF = String::trim;
        this.lastName = trimF.apply(lastName);
    }

    public void setId(Long id) {
        this.id = id;
    }

    public Optional<String> getTitle() {
        return title;
    }

    public void setTitle(Optional<String> title) {
        this.title = title;
        if (title.isPresent()) {
            this.title = Optional.ofNullable(title.get().trim());
        }
    }

}

4.1 ContactTest

I will create several unit tests to demonstrate that the contact’s getFirstName and getLastName methods return a name without any leading and trailing white-spaces.

  • contact_happypath – It constructs a contact object with the first name as " Mary Shan " and last name as " Zheng Jr ". Please note that both names have leading and trailing white-spaces. The last name also has white-spaces in the middle. With the help of the trim method, both leading and trailing white-spaces are removed and the white-spaces in the middle remains as expected.
  • contact_has_title – It sets contact’s title with ” Developer “. Please note that the leading and trailing white-spaces are removed when getTitle() returns.

ContactTest.java

package jcg.zheng.demo.entity;

import static org.junit.Assert.assertEquals;
import static org.junit.Assert.assertFalse;
import static org.junit.Assert.assertTrue;

import java.util.Optional;

import org.junit.Test;

public class ContactTest {

    @Test
    public void contact_happypath() {
        Contact contact = new Contact(" Mary shan ", " Zheng  Jr ");
        assertEquals("Mary shan", contact.getFirstName());
        assertEquals("Zheng  Jr", contact.getLastName());
    }

    @Test(expected = Exception.class)
    public void contact_miss_names() {
        Contact contact = new Contact(null, "");
    }

    @Test
    public void contact_has_no_title() {
        Contact contact = new Contact("Mary", "Zheng");
        contact.setTitle(Optional.ofNullable(null));
        assertFalse(contact.getTitle().isPresent());
    }

    @Test
    public void contact_has_title() {
        Contact contact = new Contact("Mary ", "Zheng");
        contact.setTitle(Optional.ofNullable(" Developer "));
        assertTrue(contact.getTitle().isPresent());
        assertEquals("Developer", contact.getTitle().get());
    }

}

4.2 Demo

Execute mvn test -Dtest=ContactTest. All tests should pass. Capture the output here.

Test results

C:\JCG\spring-string-trim-demo>mvn test -Dtest=ContactTest
[INFO] Scanning for projects...
[INFO]
[INFO] ---------------< jcg.zheng.demo:spring-string-trim-demo >---------------
[INFO] Building spring-jparepository-demo 0.0.1-SNAPSHOT
[INFO] --------------------------------[ jar ]---------------------------------
[INFO]
[INFO] --- maven-resources-plugin:2.6:resources (default-resources) @ spring-string-trim-demo ---
[INFO] Using 'UTF-8' encoding to copy filtered resources.
[INFO] Copying 1 resource
[INFO] Copying 0 resource
[INFO]
[INFO] --- maven-compiler-plugin:3.1:compile (default-compile) @ spring-string-trim-demo ---
[INFO] Nothing to compile - all classes are up to date
[INFO]
[INFO] --- maven-resources-plugin:2.6:testResources (default-testResources) @ spring-string-trim-demo ---
[INFO] Using 'UTF-8' encoding to copy filtered resources.
[INFO] skip non existing resourceDirectory C:\JCG\spring-string-trim-demo\src\test\resources
[INFO]
[INFO] --- maven-compiler-plugin:3.1:testCompile (default-testCompile) @ spring-string-trim-demo ---
[INFO] Nothing to compile - all classes are up to date
[INFO]
[INFO] --- maven-surefire-plugin:2.18.1:test (default-test) @ spring-string-trim-demo ---
[INFO] Surefire report directory: C:\JCG\spring-string-trim-demo\target\surefire-reports

-------------------------------------------------------
 T E S T S
-------------------------------------------------------
Running jcg.zheng.demo.entity.ContactTest
Tests run: 4, Failures: 0, Errors: 0, Skipped: 0, Time elapsed: 0.242 sec - in jcg.zheng.demo.entity.ContactTest

Results :

Tests run: 4, Failures: 0, Errors: 0, Skipped: 0

5. ContactRepository

I will create a ContactRepository class to save contacts into a database without any leading and trailing white-spaces. Click here for my other article Spring JPARepository.

CommonRepository.java

package jcg.zheng.demo.repository;

import java.util.List;

import org.springframework.data.jpa.repository.JpaRepository;
import org.springframework.data.jpa.repository.Query;
import org.springframework.data.repository.query.Param;
import org.springframework.stereotype.Repository;
import org.springframework.transaction.annotation.Transactional;

import jcg.zheng.demo.entity.Contact;

@Repository
@Transactional
public interface ContactRepository extends JpaRepository<Contact, Long> {

    @Query("SELECT con FROM Contact con  WHERE con.lastName= (:lName)")
    List<Contact> findByLastName(@Param("lName") String lName);

}

5.1 ContactRepositoryTest

We have a contact class whose constructor accepts first name and last name and three setter methods trim a string. In this step, I will create test cases with three steps:

  • Construct a contact with both leading and trailing white-spaces names.
  • Save the contact into a H2 database table.
  • Find the saved contact and check the saved values have no any leading and trailing white-spaces.

CommonRepositoryTest.java

package jcg.zheng.demo.repository;

import static org.junit.Assert.assertEquals;

import java.util.List;

import org.junit.Test;
import org.junit.runner.RunWith;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.boot.test.autoconfigure.orm.jpa.DataJpaTest;
import org.springframework.test.context.junit4.SpringRunner;

import jcg.zheng.demo.entity.Contact;

@RunWith(SpringRunner.class)
@DataJpaTest
public class ContactRepositoryTest {

    @Autowired
    private ContactRepository contactRepo;

    @Test
    public void it_can_find_the_contact_after_save_it() {
        Contact contact = new Contact(" Mary ", " Zheng");

        contactRepo.save(contact);

        List contacts = contactRepo.findAll();

        assertEquals(1, contacts.size());
        assertEquals("Mary", contacts.get(0).getFirstName());
        assertEquals("Zheng", contacts.get(0).getLastName());
    }

    @Test
    public void it_can_find_contacts_by_name() {

        contactRepo.save(new Contact(" Mary", " Zheng "));
        contactRepo.save(new Contact("Tom", "Smith"));
        contactRepo.save(new Contact("John", "Joe"));
        contactRepo.save(new Contact("Cindy ", "Zheng"));

        List contactsWithZheng = contactRepo.findByLastName("Zheng");
        assertEquals(2, contactsWithZheng.size());

        Contact foundMary = contactsWithZheng.stream()
                .filter(con -> con.getFirstName().equalsIgnoreCase("Mary"))
                .findFirst().get();
        assertEquals("Mary", foundMary.getFirstName());

        Contact foundCindy = contactsWithZheng.stream()
                .filter(con -> con.getFirstName().equalsIgnoreCase("Cindy"))
                .findAny().get();
        assertEquals("Cindy", foundCindy.getFirstName());

        contactsWithZheng = contactRepo.findByLastName(" Zheng ");
        assertEquals(0, contactsWithZheng.size());
    }

}

5.2 Demo

Execute mvn test -Dtest=ContactRepositoryTest. All tests should pass. Capture the output as the following.

Test Results

2019-02-16 11:53:20.518  INFO 17644 --- [           main] j.z.d.repository.ContactRepositoryTest   : Starting ContactRepositoryTest on S443831 with PID 17644 (started by aa00765 in C:\JCG\spring-string-trim-demo)
2019-02-16 11:53:20.519  INFO 17644 --- [           main] j.z.d.repository.ContactRepositoryTest   : No active profile set, falling back to default profiles: default
2019-02-16 11:53:20.549  INFO 17644 --- [           main] s.c.a.AnnotationConfigApplicationContext : Refreshing org.springframework.context.annotation.AnnotationConfigApplicationContext@12aba8be: startup date [Sat Feb 16 11:53:20 CST 2019]; root of context hierarchy
2019-02-16 11:53:21.505  INFO 17644 --- [           main] beddedDataSourceBeanFactoryPostProcessor : Replacing 'dataSource' DataSource bean with embedded version
2019-02-16 11:53:21.507  INFO 17644 --- [           main] o.s.b.f.s.DefaultListableBeanFactory     : Overriding bean definition for bean 'dataSource' with a different definition: replacing [Root bean: class [null]; scope=; abstract=false; lazyInit=false; autowireMode=3; dependencyCheck=0; autowireCandidate=true; primary=false; factoryBeanName=org.springframework.boot.autoconfigure.jdbc.DataSourceConfiguration$Tomcat; factoryMethodName=dataSource; initMethodName=null; destroyMethodName=(inferred); defined in class path resource [org/springframework/boot/autoconfigure/jdbc/DataSourceConfiguration$Tomcat.class]] with [Root bean: class [org.springframework.boot.test.autoconfigure.jdbc.TestDatabaseAutoConfiguration$EmbeddedDataSourceFactoryBean]; scope=; abstract=false; lazyInit=false; autowireMode=0; dependencyCheck=0; autowireCandidate=true; primary=false; factoryBeanName=null; factoryMethodName=null; initMethodName=null; destroyMethodName=null]
2019-02-16 11:53:22.090  INFO 17644 --- [           main] o.s.j.d.e.EmbeddedDatabaseFactory        : Starting embedded database: url='jdbc:h2:mem:f15dc85a-1020-4cbb-8e97-688f3367bc69;DB_CLOSE_DELAY=-1;DB_CLOSE_ON_EXIT=false', username='sa'
2019-02-16 11:53:22.930  INFO 17644 --- [           main] j.LocalContainerEntityManagerFactoryBean : Building JPA container EntityManagerFactory for persistence unit 'default'
2019-02-16 11:53:22.978  INFO 17644 --- [           main] o.hibernate.jpa.internal.util.LogHelper  : HHH000204: Processing PersistenceUnitInfo [
        name: default
        ...]
2019-02-16 11:53:23.162  INFO 17644 --- [           main] org.hibernate.Version                    : HHH000412: Hibernate Core {5.0.12.Final}
2019-02-16 11:53:23.167  INFO 17644 --- [           main] org.hibernate.cfg.Environment            : HHH000206: hibernate.properties not found
2019-02-16 11:53:23.171  INFO 17644 --- [           main] org.hibernate.cfg.Environment            : HHH000021: Bytecode provider name : javassist
2019-02-16 11:53:23.317  INFO 17644 --- [           main] o.hibernate.annotations.common.Version   : HCANN000001: Hibernate Commons Annotations {5.0.1.Final}
2019-02-16 11:53:23.711  INFO 17644 --- [           main] org.hibernate.dialect.Dialect            : HHH000400: Using dialect: org.hibernate.dialect.H2Dialect
2019-02-16 11:53:24.499  INFO 17644 --- [           main] org.hibernate.tuple.PojoInstantiator     : HHH000182: No default (no-argument) constructor for class: jcg.zheng.demo.entity.Contact (class must be instantiated by Interceptor)
2019-02-16 11:53:24.703  INFO 17644 --- [           main] org.hibernate.tool.hbm2ddl.SchemaExport  : HHH000227: Running hbm2ddl schema export
Hibernate: drop table contact if exists
Hibernate: create table contact (id bigint generated by default as identity, first_name varchar(255), last_name varchar(255), primary key (id))
2019-02-16 11:53:24.732  INFO 17644 --- [           main] org.hibernate.tool.hbm2ddl.SchemaExport  : HHH000230: Schema export complete
2019-02-16 11:53:24.844  INFO 17644 --- [           main] j.LocalContainerEntityManagerFactoryBean : Initialized JPA EntityManagerFactory for persistence unit 'default'
2019-02-16 11:53:25.279  INFO 17644 --- [           main] o.h.h.i.QueryTranslatorFactoryInitiator  : HHH000397: Using ASTQueryTranslatorFactory
2019-02-16 11:53:25.773  INFO 17644 --- [           main] j.z.d.repository.ContactRepositoryTest   : Started ContactRepositoryTest in 6.167 seconds (JVM running for 11.505)
2019-02-16 11:53:25.976  INFO 17644 --- [           main] o.s.t.c.transaction.TransactionContext   : Began transaction (1) for test context [DefaultTestContext@7c469c48 testClass = ContactRepositoryTest, testInstance = jcg.zheng.demo.repository.ContactRepositoryTest@4313f5bc, testMethod = it_can_find_contacts_by_name@ContactRepositoryTest, testException = [null], mergedContextConfiguration = [MergedContextConfiguration@12e61fe6 testClass = ContactRepositoryTest, locations = '{}', classes = '{class jcg.zheng.demo.DemoApplication}', contextInitializerClasses = '[]', activeProfiles = '{}', propertySourceLocations = '{}', propertySourceProperties = '{org.springframework.boot.test.context.SpringBootTestContextBootstrapper=true}', contextCustomizers = set[[ImportsContextCustomizer@7ee955a8 key = [org.springframework.boot.autoconfigure.cache.CacheAutoConfiguration, org.springframework.boot.autoconfigure.data.jpa.JpaRepositoriesAutoConfiguration, org.springframework.boot.autoconfigure.flyway.FlywayAutoConfiguration, org.springframework.boot.autoconfigure.jdbc.DataSourceAutoConfiguration, org.springframework.boot.autoconfigure.jdbc.DataSourceTransactionManagerAutoConfiguration, org.springframework.boot.autoconfigure.jdbc.JdbcTemplateAutoConfiguration, org.springframework.boot.autoconfigure.liquibase.LiquibaseAutoConfiguration, org.springframework.boot.autoconfigure.orm.jpa.HibernateJpaAutoConfiguration, org.springframework.boot.autoconfigure.transaction.TransactionAutoConfiguration, org.springframework.boot.test.autoconfigure.jdbc.TestDatabaseAutoConfiguration, org.springframework.boot.test.autoconfigure.orm.jpa.TestEntityManagerAutoConfiguration]], org.springframework.boot.test.context.filter.ExcludeFilterContextCustomizer@467aecef, org.springframework.boot.test.json.DuplicateJsonObjectContextCustomizerFactory$DuplicateJsonObjectContextCustomizer@2173f6d9, org.springframework.boot.test.mock.mockito.MockitoContextCustomizer@0, org.springframework.boot.test.autoconfigure.OverrideAutoConfigurationContextCustomizerFactory$DisableAutoConfigurationContextCustomizer@5bb21b69, org.springframework.boot.test.autoconfigure.filter.TypeExcludeFiltersContextCustomizer@351584c0, org.springframework.boot.test.autoconfigure.properties.PropertyMappingContextCustomizer@c763d37b, org.springframework.boot.test.autoconfigure.web.servlet.WebDriverContextCustomizerFactory$Customizer@5ed828d], contextLoader = 'org.springframework.boot.test.context.SpringBootContextLoader', parent = [null]]]; transaction manager [org.springframework.orm.jpa.JpaTransactionManager@68ee3b6d]; rollback [true]
Hibernate: insert into contact (id, first_name, last_name) values (null, ?, ?)
Hibernate: insert into contact (id, first_name, last_name) values (null, ?, ?)
Hibernate: insert into contact (id, first_name, last_name) values (null, ?, ?)
Hibernate: insert into contact (id, first_name, last_name) values (null, ?, ?)
Hibernate: select contact0_.id as id1_0_, contact0_.first_name as first_na2_0_, contact0_.last_name as last_nam3_0_ from contact contact0_ where contact0_.last_name=?
Hibernate: select contact0_.id as id1_0_, contact0_.first_name as first_na2_0_, contact0_.last_name as last_nam3_0_ from contact contact0_ where contact0_.last_name=?
2019-02-16 11:53:26.246  INFO 17644 --- [           main] o.s.t.c.transaction.TransactionContext   : Rolled back transaction for test context [DefaultTestContext@7c469c48 testClass = ContactRepositoryTest, testInstance = jcg.zheng.demo.repository.ContactRepositoryTest@4313f5bc, testMethod = it_can_find_contacts_by_name@ContactRepositoryTest, testException = [null], mergedContextConfiguration = [MergedContextConfiguration@12e61fe6 testClass = ContactRepositoryTest, locations = '{}', classes = '{class jcg.zheng.demo.DemoApplication}', contextInitializerClasses = '[]', activeProfiles = '{}', propertySourceLocations = '{}', propertySourceProperties = '{org.springframework.boot.test.context.SpringBootTestContextBootstrapper=true}', contextCustomizers = set[[ImportsContextCustomizer@7ee955a8 key = [org.springframework.boot.autoconfigure.cache.CacheAutoConfiguration, org.springframework.boot.autoconfigure.data.jpa.JpaRepositoriesAutoConfiguration, org.springframework.boot.autoconfigure.flyway.FlywayAutoConfiguration, org.springframework.boot.autoconfigure.jdbc.DataSourceAutoConfiguration, org.springframework.boot.autoconfigure.jdbc.DataSourceTransactionManagerAutoConfiguration, org.springframework.boot.autoconfigure.jdbc.JdbcTemplateAutoConfiguration, org.springframework.boot.autoconfigure.liquibase.LiquibaseAutoConfiguration, org.springframework.boot.autoconfigure.orm.jpa.HibernateJpaAutoConfiguration, org.springframework.boot.autoconfigure.transaction.TransactionAutoConfiguration, org.springframework.boot.test.autoconfigure.jdbc.TestDatabaseAutoConfiguration, org.springframework.boot.test.autoconfigure.orm.jpa.TestEntityManagerAutoConfiguration]], org.springframework.boot.test.context.filter.ExcludeFilterContextCustomizer@467aecef, org.springframework.boot.test.json.DuplicateJsonObjectContextCustomizerFactory$DuplicateJsonObjectContextCustomizer@2173f6d9, org.springframework.boot.test.mock.mockito.MockitoContextCustomizer@0, org.springframework.boot.test.autoconfigure.OverrideAutoConfigurationContextCustomizerFactory$DisableAutoConfigurationContextCustomizer@5bb21b69, org.springframework.boot.test.autoconfigure.filter.TypeExcludeFiltersContextCustomizer@351584c0, org.springframework.boot.test.autoconfigure.properties.PropertyMappingContextCustomizer@c763d37b, org.springframework.boot.test.autoconfigure.web.servlet.WebDriverContextCustomizerFactory$Customizer@5ed828d], contextLoader = 'org.springframework.boot.test.context.SpringBootContextLoader', parent = [null]]].
2019-02-16 11:53:26.262  INFO 17644 --- [           main] o.s.t.c.transaction.TransactionContext   : Began transaction (1) for test context [DefaultTestContext@7c469c48 testClass = ContactRepositoryTest, testInstance = jcg.zheng.demo.repository.ContactRepositoryTest@949c598, testMethod = it_can_find_the_contact_after_save_it@ContactRepositoryTest, testException = [null], mergedContextConfiguration = [MergedContextConfiguration@12e61fe6 testClass = ContactRepositoryTest, locations = '{}', classes = '{class jcg.zheng.demo.DemoApplication}', contextInitializerClasses = '[]', activeProfiles = '{}', propertySourceLocations = '{}', propertySourceProperties = '{org.springframework.boot.test.context.SpringBootTestContextBootstrapper=true}', contextCustomizers = set[[ImportsContextCustomizer@7ee955a8 key = [org.springframework.boot.autoconfigure.cache.CacheAutoConfiguration, org.springframework.boot.autoconfigure.data.jpa.JpaRepositoriesAutoConfiguration, org.springframework.boot.autoconfigure.flyway.FlywayAutoConfiguration, org.springframework.boot.autoconfigure.jdbc.DataSourceAutoConfiguration, org.springframework.boot.autoconfigure.jdbc.DataSourceTransactionManagerAutoConfiguration, org.springframework.boot.autoconfigure.jdbc.JdbcTemplateAutoConfiguration, org.springframework.boot.autoconfigure.liquibase.LiquibaseAutoConfiguration, org.springframework.boot.autoconfigure.orm.jpa.HibernateJpaAutoConfiguration, org.springframework.boot.autoconfigure.transaction.TransactionAutoConfiguration, org.springframework.boot.test.autoconfigure.jdbc.TestDatabaseAutoConfiguration, org.springframework.boot.test.autoconfigure.orm.jpa.TestEntityManagerAutoConfiguration]], org.springframework.boot.test.context.filter.ExcludeFilterContextCustomizer@467aecef, org.springframework.boot.test.json.DuplicateJsonObjectContextCustomizerFactory$DuplicateJsonObjectContextCustomizer@2173f6d9, org.springframework.boot.test.mock.mockito.MockitoContextCustomizer@0, org.springframework.boot.test.autoconfigure.OverrideAutoConfigurationContextCustomizerFactory$DisableAutoConfigurationContextCustomizer@5bb21b69, org.springframework.boot.test.autoconfigure.filter.TypeExcludeFiltersContextCustomizer@351584c0, org.springframework.boot.test.autoconfigure.properties.PropertyMappingContextCustomizer@c763d37b, org.springframework.boot.test.autoconfigure.web.servlet.WebDriverContextCustomizerFactory$Customizer@5ed828d], contextLoader = 'org.springframework.boot.test.context.SpringBootContextLoader', parent = [null]]]; transaction manager [org.springframework.orm.jpa.JpaTransactionManager@68ee3b6d]; rollback [true]
Hibernate: insert into contact (id, first_name, last_name) values (null, ?, ?)
Hibernate: select contact0_.id as id1_0_, contact0_.first_name as first_na2_0_, contact0_.last_name as last_nam3_0_ from contact contact0_
2019-02-16 11:53:26.375  INFO 17644 --- [           main] o.s.t.c.transaction.TransactionContext   : Rolled back transaction for test context [DefaultTestContext@7c469c48 testClass = ContactRepositoryTest, testInstance = jcg.zheng.demo.repository.ContactRepositoryTest@949c598, testMethod = it_can_find_the_contact_after_save_it@ContactRepositoryTest, testException = [null], mergedContextConfiguration = [MergedContextConfiguration@12e61fe6 testClass = ContactRepositoryTest, locations = '{}', classes = '{class jcg.zheng.demo.DemoApplication}', contextInitializerClasses = '[]', activeProfiles = '{}', propertySourceLocations = '{}', propertySourceProperties = '{org.springframework.boot.test.context.SpringBootTestContextBootstrapper=true}', contextCustomizers = set[[ImportsContextCustomizer@7ee955a8 key = [org.springframework.boot.autoconfigure.cache.CacheAutoConfiguration, org.springframework.boot.autoconfigure.data.jpa.JpaRepositoriesAutoConfiguration, org.springframework.boot.autoconfigure.flyway.FlywayAutoConfiguration, org.springframework.boot.autoconfigure.jdbc.DataSourceAutoConfiguration, org.springframework.boot.autoconfigure.jdbc.DataSourceTransactionManagerAutoConfiguration, org.springframework.boot.autoconfigure.jdbc.JdbcTemplateAutoConfiguration, org.springframework.boot.autoconfigure.liquibase.LiquibaseAutoConfiguration, org.springframework.boot.autoconfigure.orm.jpa.HibernateJpaAutoConfiguration, org.springframework.boot.autoconfigure.transaction.TransactionAutoConfiguration, org.springframework.boot.test.autoconfigure.jdbc.TestDatabaseAutoConfiguration, org.springframework.boot.test.autoconfigure.orm.jpa.TestEntityManagerAutoConfiguration]], org.springframework.boot.test.context.filter.ExcludeFilterContextCustomizer@467aecef, org.springframework.boot.test.json.DuplicateJsonObjectContextCustomizerFactory$DuplicateJsonObjectContextCustomizer@2173f6d9, org.springframework.boot.test.mock.mockito.MockitoContextCustomizer@0, org.springframework.boot.test.autoconfigure.OverrideAutoConfigurationContextCustomizerFactory$DisableAutoConfigurationContextCustomizer@5bb21b69, org.springframework.boot.test.autoconfigure.filter.TypeExcludeFiltersContextCustomizer@351584c0, org.springframework.boot.test.autoconfigure.properties.PropertyMappingContextCustomizer@c763d37b, org.springframework.boot.test.autoconfigure.web.servlet.WebDriverContextCustomizerFactory$Customizer@5ed828d], contextLoader = 'org.springframework.boot.test.context.SpringBootContextLoader', parent = [null]]].
Tests run: 2, Failures: 0, Errors: 0, Skipped: 0, Time elapsed: 7.687 sec - in jcg.zheng.demo.repository.ContactRepositoryTest
2019-02-16 11:53:26.392  INFO 17644 --- [       Thread-3] s.c.a.AnnotationConfigApplicationContext : Closing org.springframework.context.annotation.AnnotationConfigApplicationContext@12aba8be: startup date [Sat Feb 16 11:53:20 CST 2019]; root of context hierarchy
2019-02-16 11:53:26.399  INFO 17644 --- [       Thread-3] j.LocalContainerEntityManagerFactoryBean : Closing JPA EntityManagerFactory for persistence unit 'default'
2019-02-16 11:53:26.400  INFO 17644 --- [       Thread-3] org.hibernate.tool.hbm2ddl.SchemaExport  : HHH000227: Running hbm2ddl schema export
Hibernate: drop table contact if exists
2019-02-16 11:53:26.415  INFO 17644 --- [       Thread-3] org.hibernate.tool.hbm2ddl.SchemaExport  : HHH000230: Schema export complete

Results :

Tests run: 2, Failures: 0, Errors: 0, Skipped: 0

[INFO] ------------------------------------------------------------------------
[INFO] BUILD SUCCESS
[INFO] ------------------------------------------------------------------------
[INFO] Total time:  28.066 s
[INFO] Finished at: 2019-02-16T11:53:26-06:00
[INFO] ------------------------------------------------------------------------

C:\JCG\spring-string-trim-demo>

6. Java String trim() method – Summary

In this example, I demonstrated how to trim a string value in three ways:

  • Create a Function to trim a string in JDK8+
  • Invoke trim for a non-null String object
  • Invoke trim for an Optional String object

7. Download the Source Code

This example consists of a Maven project which trims a string before saving it into a database table.

Download
You can download the full source code of this example here: Java String trim() method with Example

Last updated on May 7th, 2020

Photo of Mary Zheng Mary ZhengFebruary 26th, 2019Last Updated: September 28th, 2020
0 267 9 minutes read
Photo of Mary Zheng

Mary Zheng

Mary has graduated from Mechanical Engineering department at ShangHai JiaoTong University. She also holds a Master degree in Computer Science from Webster University. During her studies she has been involved with a large number of projects ranging from programming and software engineering. She works as a senior Software Engineer in the telecommunications sector where she acts as a leader and works with others to design, implement, and monitor the software solution.
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