ArrayList 5.11

ArrayList实例化与使用
本文介绍了ArrayList<String>的实例化方法及其基本用法,包括如何声明一个ArrayList对象并进行初始化。此外还展示了如何定义全局变量及局部变量,并提供了ArrayList中元素删除的操作示例。

ArrayList的实例化方法

ArrayList<String>stringList = new ArrayList<String>();



ArrayList:长度可变的数组,集合对象


static  ArrayList<String>list

//全局变量--在整个类范围定义的,所有方法都可见


//在方法内部定义的,称之为局部变量

int a = 10;

system.out.println(a);

system.out.println(list);


快捷键:ctrl+Alt+↓ 向下复制整行       ctrl+D 删除整行


删除:studentlist.remove(studentList.size()-1);

           System.out.println();






org.springframework.beans.factory.BeanCreationException: Error creating bean with name 'org.springbppt.example.com.MybatisTestApplicationTests': Injection of resource dependencies failed at org.springframework.context.annotation.CommonAnnotationBeanPostProcessor.postProcessProperties(CommonAnnotationBeanPostProcessor.java:372) ~[spring-context-6.2.6.jar:6.2.6] at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.populateBean(AbstractAutowireCapableBeanFactory.java:1451) ~[spring-beans-6.2.6.jar:6.2.6] at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.autowireBeanProperties(AbstractAutowireCapableBeanFactory.java:405) ~[spring-beans-6.2.6.jar:6.2.6] at org.springframework.test.context.support.DependencyInjectionTestExecutionListener.injectDependencies(DependencyInjectionTestExecutionListener.java:156) ~[spring-test-6.2.6.jar:6.2.6] at org.springframework.test.context.support.DependencyInjectionTestExecutionListener.prepareTestInstance(DependencyInjectionTestExecutionListener.java:111) ~[spring-test-6.2.6.jar:6.2.6] at org.springframework.test.context.TestContextManager.prepareTestInstance(TestContextManager.java:260) ~[spring-test-6.2.6.jar:6.2.6] at org.springframework.test.context.junit.jupiter.SpringExtension.postProcessTestInstance(SpringExtension.java:159) ~[spring-test-6.2.6.jar:6.2.6] at org.junit.jupiter.engine.descriptor.ClassBasedTestDescriptor.lambda$invokeTestInstancePostProcessors$11(ClassBasedTestDescriptor.java:378) ~[junit-jupiter-engine-5.11.4.jar:5.11.4] at org.junit.jupiter.engine.descriptor.ClassBasedTestDescriptor.executeAndMaskThrowable(ClassBasedTestDescriptor.java:383) ~[junit-jupiter-engine-5.11.4.jar:5.11.4] at org.junit.jupiter.engine.descriptor.ClassBasedTestDescriptor.lambda$invokeTestInstancePostProcessors$12(ClassBasedTestDescriptor.java:378) ~[junit-jupiter-engine-5.11.4.jar:5.11.4] at java.base/java.util.stream.ForEachOps$ForEachOp$OfRef.accept(ForEachOps.java:183) ~[na:na] at java.base/java.util.stream.ReferencePipeline$3$1.accept(ReferencePipeline.java:197) ~[na:na] at java.base/java.util.stream.ReferencePipeline$2$1.accept(ReferencePipeline.java:179) ~[na:na] at java.base/java.util.stream.ReferencePipeline$3$1.accept(ReferencePipeline.java:197) ~[na:na] at java.base/java.util.ArrayList$ArrayListSpliterator.forEachRemaining(ArrayList.java:1625) ~[na:na] at java.base/java.util.stream.AbstractPipeline.copyInto(AbstractPipeline.java:509) ~[na:na] at java.base/java.util.stream.AbstractPipeline.wrapAndCopyInto(AbstractPipeline.java:499) ~[na:na] at java.base/java.util.stream.ForEachOps$ForEachOp.evaluateSequential(ForEachOps.java:150) ~[na:na] at java.base/java.util.stream.ForEachOps$ForEachOp$OfRef.evaluateSequential(ForEachOps.java:173) ~[na:na] at java.base/java.util.stream.AbstractPipeline.evaluate(AbstractPipeline.java:234) ~[na:na] at java.base/java.util.stream.ReferencePipeline.forEach(ReferencePipeline.java:596) ~[na:na] at org.junit.jupiter.engine.descriptor.ClassBasedTestDescriptor.invokeTestInstancePostProcessors(ClassBasedTestDescriptor.java:377) ~[junit-jupiter-engine-5.11.4.jar:5.11.4] at org.junit.jupiter.engine.descriptor.ClassBasedTestDescriptor.lambda$instantiateAndPostProcessTestInstance$7(ClassBasedTestDescriptor.java:290) ~[junit-jupiter-engine-5.11.4.jar:5.11.4] at org.junit.platform.engine.support.hierarchical.ThrowableCollector.execute(ThrowableCollector.java:73) ~[junit-platform-engine-1.11.4.jar:1.11.4] at org.junit.jupiter.engine.descriptor.ClassBasedTestDescriptor.instantiateAndPostProcessTestInstance(ClassBasedTestDescriptor.java:289) ~[junit-jupiter-engine-5.11.4.jar:5.11.4] at org.junit.jupiter.engine.descriptor.ClassBasedTestDescriptor.lambda$testInstancesProvider$5(ClassBasedTestDescriptor.java:279) ~[junit-jupiter-engine-5.11.4.jar:5.11.4] at java.base/java.util.Optional.orElseGet(Optional.java:364) ~[na:na] at org.junit.jupiter.engine.descriptor.ClassBasedTestDescriptor.lambda$testInstancesProvider$6(ClassBasedTestDescriptor.java:278) ~[junit-jupiter-engine-5.11.4.jar:5.11.4] at org.junit.jupiter.engine.execution.TestInstancesProvider.getTestInstances(TestInstancesProvider.java:31) ~[junit-jupiter-engine-5.11.4.jar:5.11.4] at org.junit.jupiter.engine.descriptor.TestMethodTestDescriptor.lambda$prepare$1(TestMethodTestDescriptor.java:105) ~[junit-jupiter-engine-5.11.4.jar:5.11.4] at org.junit.platform.engine.support.hierarchical.ThrowableCollector.execute(ThrowableCollector.java:73) ~[junit-platform-engine-1.11.4.jar:1.11.4] at org.junit.jupiter.engine.descriptor.TestMethodTestDescriptor.prepare(TestMethodTestDescriptor.java:104) ~[junit-jupiter-engine-5.11.4.jar:5.11.4] at org.junit.jupiter.engine.descriptor.TestMethodTestDescriptor.prepare(TestMethodTestDescriptor.java:68) ~[junit-jupiter-engine-5.11.4.jar:5.11.4] at org.junit.platform.engine.support.hierarchical.NodeTestTask.lambda$prepare$2(NodeTestTask.java:128) ~[junit-platform-engine-1.11.4.jar:1.11.4] at org.junit.platform.engine.support.hierarchical.ThrowableCollector.execute(ThrowableCollector.java:73) ~[junit-platform-engine-1.11.4.jar:1.11.4] at org.junit.platform.engine.support.hierarchical.NodeTestTask.prepare(NodeTestTask.java:128) ~[junit-platform-engine-1.11.4.jar:1.11.4] at org.junit.platform.engine.support.hierarchical.NodeTestTask.execute(NodeTestTask.java:95) ~[junit-platform-engine-1.11.4.jar:1.11.4] at java.base/java.util.ArrayList.forEach(ArrayList.java:1511) ~[na:na] at org.junit.platform.engine.support.hierarchical.SameThreadHierarchicalTestExecutorService.invokeAll(SameThreadHierarchicalTestExecutorService.java:41) ~[junit-platform-engine-1.11.4.jar:1.11.4] at org.junit.platform.engine.support.hierarchical.NodeTestTask.lambda$executeRecursively$6(NodeTestTask.java:160) ~[junit-platform-engine-1.11.4.jar:1.11.4] at org.junit.platform.engine.support.hierarchical.ThrowableCollector.execute(ThrowableCollector.java:73) ~[junit-platform-engine-1.11.4.jar:1.11.4] at org.junit.platform.engine.support.hierarchical.NodeTestTask.lambda$executeRecursively$8(NodeTestTask.java:146) ~[junit-platform-engine-1.11.4.jar:1.11.4] at org.junit.platform.engine.support.hierarchical.Node.around(Node.java:137) ~[junit-platform-engine-1.11.4.jar:1.11.4] at org.junit.platform.engine.support.hierarchical.NodeTestTask.lambda$executeRecursively$9(NodeTestTask.java:144) ~[junit-platform-engine-1.11.4.jar:1.11.4] at org.junit.platform.engine.support.hierarchical.ThrowableCollector.execute(ThrowableCollector.java:73) ~[junit-platform-engine-1.11.4.jar:1.11.4] at org.junit.platform.engine.support.hierarchical.NodeTestTask.executeRecursively(NodeTestTask.java:143) ~[junit-platform-engine-1.11.4.jar:1.11.4] at org.junit.platform.engine.support.hierarchical.NodeTestTask.execute(NodeTestTask.java:100) ~[junit-platform-engine-1.11.4.jar:1.11.4] at java.base/java.util.ArrayList.forEach(ArrayList.java:1511) ~[na:na] at org.junit.platform.engine.support.hierarchical.SameThreadHierarchicalTestExecutorService.invokeAll(SameThreadHierarchicalTestExecutorService.java:41) ~[junit-platform-engine-1.11.4.jar:1.11.4] at org.junit.platform.engine.support.hierarchical.NodeTestTask.lambda$executeRecursively$6(NodeTestTask.java:160) ~[junit-platform-engine-1.11.4.jar:1.11.4] at org.junit.platform.engine.support.hierarchical.ThrowableCollector.execute(ThrowableCollector.java:73) ~[junit-platform-engine-1.11.4.jar:1.11.4] at org.junit.platform.engine.support.hierarchical.NodeTestTask.lambda$executeRecursively$8(NodeTestTask.java:146) ~[junit-platform-engine-1.11.4.jar:1.11.4] at org.junit.platform.engine.support.hierarchical.Node.around(Node.java:137) ~[junit-platform-engine-1.11.4.jar:1.11.4] at org.junit.platform.engine.support.hierarchical.NodeTestTask.lambda$executeRecursively$9(NodeTestTask.java:144) ~[junit-platform-engine-1.11.4.jar:1.11.4] at org.junit.platform.engine.support.hierarchical.ThrowableCollector.execute(ThrowableCollector.java:73) ~[junit-platform-engine-1.11.4.jar:1.11.4] at org.junit.platform.engine.support.hierarchical.NodeTestTask.executeRecursively(NodeTestTask.java:143) ~[junit-platform-engine-1.11.4.jar:1.11.4] at org.junit.platform.engine.support.hierarchical.NodeTestTask.execute(NodeTestTask.java:100) ~[junit-platform-engine-1.11.4.jar:1.11.4] at org.junit.platform.engine.support.hierarchical.SameThreadHierarchicalTestExecutorService.submit(SameThreadHierarchicalTestExecutorService.java:35) ~[junit-platform-engine-1.11.4.jar:1.11.4] at org.junit.platform.engine.support.hierarchical.HierarchicalTestExecutor.execute(HierarchicalTestExecutor.java:57) ~[junit-platform-engine-1.11.4.jar:1.11.4] at org.junit.platform.engine.support.hierarchical.HierarchicalTestEngine.execute(HierarchicalTestEngine.java:54) ~[junit-platform-engine-1.11.4.jar:1.11.4] at org.junit.platform.launcher.core.EngineExecutionOrchestrator.execute(EngineExecutionOrchestrator.java:198) ~[junit-platform-launcher-1.11.4.jar:1.11.4] at org.junit.platform.launcher.core.EngineExecutionOrchestrator.execute(EngineExecutionOrchestrator.java:169) ~[junit-platform-launcher-1.11.4.jar:1.11.4] at org.junit.platform.launcher.core.EngineExecutionOrchestrator.execute(EngineExecutionOrchestrator.java:93) ~[junit-platform-launcher-1.11.4.jar:1.11.4] at org.junit.platform.launcher.core.EngineExecutionOrchestrator.lambda$execute$0(EngineExecutionOrchestrator.java:58) ~[junit-platform-launcher-1.11.4.jar:1.11.4] at org.junit.platform.launcher.core.EngineExecutionOrchestrator.withInterceptedStreams(EngineExecutionOrchestrator.java:141) ~[junit-platform-launcher-1.11.4.jar:1.11.4] at org.junit.platform.launcher.core.EngineExecutionOrchestrator.execute(EngineExecutionOrchestrator.java:57) ~[junit-platform-launcher-1.11.4.jar:1.11.4] at org.junit.platform.launcher.core.DefaultLauncher.execute(DefaultLauncher.java:103) ~[junit-platform-launcher-1.11.4.jar:1.11.4] at org.junit.platform.launcher.core.DefaultLauncher.execute(DefaultLauncher.java:85) ~[junit-platform-launcher-1.11.4.jar:1.11.4] at org.junit.platform.launcher.core.DelegatingLauncher.execute(DelegatingLauncher.java:47) ~[junit-platform-launcher-1.11.4.jar:1.11.4] at org.junit.platform.launcher.core.SessionPerRequestLauncher.execute(SessionPerRequestLauncher.java:63) ~[junit-platform-launcher-1.11.4.jar:1.11.4] at com.intellij.junit5.JUnit5IdeaTestRunner.startRunnerWithArgs(JUnit5IdeaTestRunner.java:57) ~[junit5-rt.jar:na] at com.intellij.rt.junit.IdeaTestRunner$Repeater$1.execute(IdeaTestRunner.java:38) ~[junit-rt.jar:na] at com.intellij.rt.execution.junit.TestsRepeater.repeat(TestsRepeater.java:11) ~[idea_rt.jar:na] at com.intellij.rt.junit.IdeaTestRunner$Repeater.startRunnerWithArgs(IdeaTestRunner.java:35) ~[junit-rt.jar:na] at com.intellij.rt.junit.JUnitStarter.prepareStreamsAndStart(JUnitStarter.java:232) ~[junit-rt.jar:na] at com.intellij.rt.junit.JUnitStarter.main(JUnitStarter.java:55) ~[junit-rt.jar:na] Caused by: org.springframework.beans.factory.NoSuchBeanDefinitionException: No qualifying bean of type 'mapper.UserMapper' available: expected at least 1 bean which qualifies as autowire candidate. Dependency annotations: {@jakarta.annotation.Resource(shareable=true, lookup="", name="", description="", authenticationType=CONTAINER, type=java.lang.Object.class, mappedName="")} at org.springframework.beans.factory.support.DefaultListableBeanFactory.raiseNoMatchingBeanFound(DefaultListableBeanFactory.java:2279) ~[spring-beans-6.2.6.jar:6.2.6] at org.springframework.beans.factory.support.DefaultListableBeanFactory.doResolveDependency(DefaultListableBeanFactory.java:1702) ~[spring-beans-6.2.6.jar:6.2.6] at org.springframework.beans.factory.support.DefaultListableBeanFactory.resolveDependency(DefaultListableBeanFactory.java:1627) ~[spring-beans-6.2.6.jar:6.2.6] at org.springframework.context.annotation.CommonAnnotationBeanPostProcessor.autowireResource(CommonAnnotationBeanPostProcessor.java:599) ~[spring-context-6.2.6.jar:6.2.6] at org.springframework.context.annotation.CommonAnnotationBeanPostProcessor.getResource(CommonAnnotationBeanPostProcessor.java:577) ~[spring-context-6.2.6.jar:6.2.6] at org.springframework.context.annotation.CommonAnnotationBeanPostProcessor$ResourceElement.getResourceToInject(CommonAnnotationBeanPostProcessor.java:739) ~[spring-context-6.2.6.jar:6.2.6] at org.springframework.beans.factory.annotation.InjectionMetadata$InjectedElement.inject(InjectionMetadata.java:272) ~[spring-beans-6.2.6.jar:6.2.6] at org.springframework.beans.factory.annotation.InjectionMetadata.inject(InjectionMetadata.java:146) ~[spring-beans-6.2.6.jar:6.2.6] at org.springframework.context.annotation.CommonAnnotationBeanPostProcessor.postProcessProperties(CommonAnnotationBeanPostProcessor.java:369) ~[spring-context-6.2.6.jar:6.2.6] ... 75 common frames omitted org.springframework.beans.factory.BeanCreationException: Error creating bean with name 'org.springbppt.example.com.MybatisTestApplicationTests': Injection of resource dependencies failed at org.springframework.context.annotation.CommonAnnotationBeanPostProcessor.postProcessProperties(CommonAnnotationBeanPostProcessor.java:372) at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.populateBean(AbstractAutowireCapableBeanFactory.java:1451) at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.autowireBeanProperties(AbstractAutowireCapableBeanFactory.java:405) at org.springframework.test.context.support.DependencyInjectionTestExecutionListener.injectDependencies(DependencyInjectionTestExecutionListener.java:156) at org.springframework.test.context.support.DependencyInjectionTestExecutionListener.prepareTestInstance(DependencyInjectionTestExecutionListener.java:111) at org.springframework.test.context.TestContextManager.prepareTestInstance(TestContextManager.java:260) at org.springframework.test.context.junit.jupiter.SpringExtension.postProcessTestInstance(SpringExtension.java:159) at java.base/java.util.stream.ForEachOps$ForEachOp$OfRef.accept(ForEachOps.java:183) at java.base/java.util.stream.ReferencePipeline$3$1.accept(ReferencePipeline.java:197) at java.base/java.util.stream.ReferencePipeline$2$1.accept(ReferencePipeline.java:179) at java.base/java.util.stream.ReferencePipeline$3$1.accept(ReferencePipeline.java:197) at java.base/java.util.ArrayList$ArrayListSpliterator.forEachRemaining(ArrayList.java:1625) at java.base/java.util.stream.AbstractPipeline.copyInto(AbstractPipeline.java:509) at java.base/java.util.stream.AbstractPipeline.wrapAndCopyInto(AbstractPipeline.java:499) at java.base/java.util.stream.ForEachOps$ForEachOp.evaluateSequential(ForEachOps.java:150) at java.base/java.util.stream.ForEachOps$ForEachOp$OfRef.evaluateSequential(ForEachOps.java:173) at java.base/java.util.stream.AbstractPipeline.evaluate(AbstractPipeline.java:234) at java.base/java.util.stream.ReferencePipeline.forEach(ReferencePipeline.java:596) at java.base/java.util.Optional.orElseGet(Optional.java:364) at java.base/java.util.ArrayList.forEach(ArrayList.java:1511) at java.base/java.util.ArrayList.forEach(ArrayList.java:1511) Caused by: org.springframework.beans.factory.NoSuchBeanDefinitionException: No qualifying bean of type 'mapper.UserMapper' available: expected at least 1 bean which qualifies as autowire candidate. Dependency annotations: {@jakarta.annotation.Resource(shareable=true, lookup="", name="", description="", authenticationType=CONTAINER, type=java.lang.Object.class, mappedName="")} at org.springframework.beans.factory.support.DefaultListableBeanFactory.raiseNoMatchingBeanFound(DefaultListableBeanFactory.java:2279) at org.springframework.beans.factory.support.DefaultListableBeanFactory.doResolveDependency(DefaultListableBeanFactory.java:1702) at org.springframework.beans.factory.support.DefaultListableBeanFactory.resolveDependency(DefaultListableBeanFactory.java:1627) at org.springframework.context.annotation.CommonAnnotationBeanPostProcessor.autowireResource(CommonAnnotationBeanPostProcessor.java:599) at org.springframework.context.annotation.CommonAnnotationBeanPostProcessor.getResource(CommonAnnotationBeanPostProcessor.java:577) at org.springframework.context.annotation.CommonAnnotationBeanPostProcessor$ResourceElement.getResourceToInject(CommonAnnotationBeanPostProcessor.java:739) at org.springframework.beans.factory.annotation.InjectionMetadata$InjectedElement.inject(InjectionMetadata.java:272) at org.springframework.beans.factory.annotation.InjectionMetadata.inject(InjectionMetadata.java:146) at org.springframework.context.annotation.CommonAnnotationBeanPostProcessor.postProcessProperties(CommonAnnotationBeanPostProcessor.java:369) ... 20 more
05-10
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