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                        /JUnit—Java单元测试必备工具

空指针异常

applicationContext.xml

<?xml version="1.0" encoding="UTF-8"?>
<beans
    xmlns="http://www.springframework.org/schema/beans"
    xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
    xmlns:p="http://www.springframework.org/schema/p"
    xsi:schemaLocation="http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans-3.0.xsd">  
    <!-- 配置需要被Spring管理的Bean（创建，创建后放在了Spring IOC容器里面）-->
    <bean id="date" class="java.util.Date">
        <!-- 配置该Bean需要注入的属性（是通过属性set方法来注入的） -->
       <!--<property name="info" value="Happy New Year!"/>  --> 
    </bean>
</beans>

springTest.java

package com.imooc.confirm;
import java.util.Date;
import org.junit.BeforeClass;
import org.junit.jupiter.api.Test;
import org.springframework.context.ApplicationContext;
import org.springframework.context.support.ClassPathXmlApplicationContext;
public class springTest {
private static ApplicationContext context =null;
@BeforeClass
public static void setUpBeforeClass() throws Exception {
context=new ClassPathXmlApplicationContext("applicationContext.xml");
}
@Test
public void test() {
Date date=(Date) context.getBean("date");
System.out.println(date);
}
}

运行后报空指针异常，下面是Failure Trace

java.lang.NullPointerException

at com.imooc.confirm.springTest.test(springTest.java:22)

at java.base/jdk.internal.reflect.NativeMethodAccessorImpl.invoke0(Native Method)

at java.base/jdk.internal.reflect.NativeMethodAccessorImpl.invoke(Unknown Source)

at java.base/jdk.internal.reflect.DelegatingMethodAccessorImpl.invoke(Unknown Source)

at java.base/java.lang.reflect.Method.invoke(Unknown Source)

at org.junit.platform.commons.util.ReflectionUtils.invokeMethod(ReflectionUtils.java:389)

at org.junit.jupiter.engine.execution.ExecutableInvoker.invoke(ExecutableInvoker.java:115)

at org.junit.jupiter.engine.descriptor.TestMethodTestDescriptor.lambda$invokeTestMethod$6(TestMethodTestDescriptor.java:167)

at org.junit.jupiter.engine.execution.ThrowableCollector.execute(ThrowableCollector.java:40)

at org.junit.jupiter.engine.descriptor.TestMethodTestDescriptor.invokeTestMethod(TestMethodTestDescriptor.java:163)

at org.junit.jupiter.engine.descriptor.TestMethodTestDescriptor.execute(TestMethodTestDescriptor.java:110)

at org.junit.jupiter.engine.descriptor.TestMethodTestDescriptor.execute(TestMethodTestDescriptor.java:57)

at org.junit.platform.engine.support.hierarchical.HierarchicalTestExecutor.lambda$execute$3(HierarchicalTestExecutor.java:83)

at org.junit.platform.engine.support.hierarchical.SingleTestExecutor.executeSafely(SingleTestExecutor.java:66)

at org.junit.platform.engine.support.hierarchical.HierarchicalTestExecutor.execute(HierarchicalTestExecutor.java:77)

at org.junit.platform.engine.support.hierarchical.HierarchicalTestExecutor.lambda$null$2(HierarchicalTestExecutor.java:92)

at java.base/java.util.stream.ForEachOps$ForEachOp$OfRef.accept(Unknown Source)

at java.base/java.util.stream.ReferencePipeline$2$1.accept(Unknown Source)

at java.base/java.util.Iterator.forEachRemaining(Unknown Source)

at java.base/java.util.Spliterators$IteratorSpliterator.forEachRemaining(Unknown Source)

at java.base/java.util.stream.AbstractPipeline.copyInto(Unknown Source)

at java.base/java.util.stream.AbstractPipeline.wrapAndCopyInto(Unknown Source)

at java.base/java.util.stream.ForEachOps$ForEachOp.evaluateSequential(Unknown Source)

at java.base/java.util.stream.ForEachOps$ForEachOp$OfRef.evaluateSequential(Unknown Source)

at java.base/java.util.stream.AbstractPipeline.evaluate(Unknown Source)

at java.base/java.util.stream.ReferencePipeline.forEach(Unknown Source)

at org.junit.platform.engine.support.hierarchical.HierarchicalTestExecutor.lambda$execute$3(HierarchicalTestExecutor.java:92)