【基础知识】java中基本类型与引用类型变量的区别

蔚落 2023-02-15 07:57 21阅读 0赞

一。基本类型

基本类型包括String,  8中基本类型（byte, int, shaort, long, float, double, char, boolen）

二。引用类型

是一个对象，我们创建一个对象后，会存对象所在的地址

Map map = new HashMap();

map存的是 这个Map锁指向的地址

三。引用传递和值传递

我们在方法中，在传参的时候会分为直传递和引用传递，传的如果是对象那就是引用传递，传的是基本类型那就是值传递，会有什么影响呢？或者说在方法中有什么区别呢？我们在做个实验，我写一个方法，如下：

package com.example.demo;
    
    import java.util.ArrayList;
    import java.util.HashMap;
    import java.util.List;
    import java.util.Map;
    
    public class Demo01 {
    
        public static void main(String[] args) {
            String a = "aaaa";
            int b = 0;
            long c = 2000000l;
            double d = 34.8888;
            boolean e = false;
            char f = 'f';
            Map map = new HashMap();
            List list = new ArrayList();
            System.out.println("----------------调用方法前----------------");
    
            System.out.println("a:"+a);
            System.out.println("b:"+b);
            System.out.println("c:"+c);
            System.out.println("d:"+d);
            System.out.println("e:"+e);
            System.out.println("f:"+f);
            System.out.println("map:"+map);
            System.out.println("list:"+list);
    
            method(a, b, c, d, e, f, map, list);
    
            System.out.println("----------------调用方法前----------------");
    
            System.out.println("----------------调用方法后----------------");
            System.out.println("a:"+a);
            System.out.println("b:"+b);
            System.out.println("c:"+c);
            System.out.println("d:"+d);
            System.out.println("e:"+e);
            System.out.println("f:"+f);
            System.out.println("map:"+map.toString());
            System.out.println("list:"+list.toString());
            System.out.println("----------------调用方法后----------------");
        }
    
        private static void method(String a, int b, long c, double d, boolean e, char f, Map map, List list){
            a = "bbbbbb";
            b = 1;
            c = 100000000l;
            d = -334.33333;
            e = true;
            f = 't';
            map.put("a1", "4444");
            map.put("a2", "fffff");
            list.add("list1");
            list.add("list2");
            list.add("list3");
        }
    
    }

我们看在main方法中 我们首先初始化了 一些基本类型的数据 和两个引用类型（Map和List），此时输出应该是初始化的数据，接下来我们写了一个方法，把刚才的这些参数都传进去，然后在这个method方法里面，对这些参数做了一些修改，没有返回值。

结果为：

/Library/Java/JavaVirtualMachines/jdk1.8.0_181.jdk/Contents/Home/bin/java "-javaagent:/Applications/IntelliJ IDEA.app/Contents/lib/idea_rt.jar=64029:/Applications/IntelliJ IDEA.app/Contents/bin" -Dfile.encoding=UTF-8 -classpath /Library/Java/JavaVirtualMachines/jdk1.8.0_181.jdk/Contents/Home/jre/lib/charsets.jar:/Library/Java/JavaVirtualMachines/jdk1.8.0_181.jdk/Contents/Home/jre/lib/deploy.jar:/Library/Java/JavaVirtualMachines/jdk1.8.0_181.jdk/Contents/Home/jre/lib/ext/cldrdata.jar:/Library/Java/JavaVirtualMachines/jdk1.8.0_181.jdk/Contents/Home/jre/lib/ext/dnsns.jar:/Library/Java/JavaVirtualMachines/jdk1.8.0_181.jdk/Contents/Home/jre/lib/ext/jaccess.jar:/Library/Java/JavaVirtualMachines/jdk1.8.0_181.jdk/Contents/Home/jre/lib/ext/jfxrt.jar:/Library/Java/JavaVirtualMachines/jdk1.8.0_181.jdk/Contents/Home/jre/lib/ext/localedata.jar:/Library/Java/JavaVirtualMachines/jdk1.8.0_181.jdk/Contents/Home/jre/lib/ext/nashorn.jar:/Library/Java/JavaVirtualMachines/jdk1.8.0_181.jdk/Contents/Home/jre/lib/ext/sunec.jar:/Library/Java/JavaVirtualMachines/jdk1.8.0_181.jdk/Contents/Home/jre/lib/ext/sunjce_provider.jar:/Library/Java/JavaVirtualMachines/jdk1.8.0_181.jdk/Contents/Home/jre/lib/ext/sunpkcs11.jar:/Library/Java/JavaVirtualMachines/jdk1.8.0_181.jdk/Contents/Home/jre/lib/ext/zipfs.jar:/Library/Java/JavaVirtualMachines/jdk1.8.0_181.jdk/Contents/Home/jre/lib/javaws.jar:/Library/Java/JavaVirtualMachines/jdk1.8.0_181.jdk/Contents/Home/jre/lib/jce.jar:/Library/Java/JavaVirtualMachines/jdk1.8.0_181.jdk/Contents/Home/jre/lib/jfr.jar:/Library/Java/JavaVirtualMachines/jdk1.8.0_181.jdk/Contents/Home/jre/lib/jfxswt.jar:/Library/Java/JavaVirtualMachines/jdk1.8.0_181.jdk/Contents/Home/jre/lib/jsse.jar:/Library/Java/JavaVirtualMachines/jdk1.8.0_181.jdk/Contents/Home/jre/lib/management-agent.jar:/Library/Java/JavaVirtualMachines/jdk1.8.0_181.jdk/Contents/Home/jre/lib/plugin.jar:/Library/Java/JavaVirtualMachines/jdk1.8.0_181.jdk/Contents/Home/jre/lib/resources.jar:/Library/Java/JavaVirtualMachines/jdk1.8.0_181.jdk/Contents/Home/jre/lib/rt.jar:/Library/Java/JavaVirtualMachines/jdk1.8.0_181.jdk/Contents/Home/lib/ant-javafx.jar:/Library/Java/JavaVirtualMachines/jdk1.8.0_181.jdk/Contents/Home/lib/dt.jar:/Library/Java/JavaVirtualMachines/jdk1.8.0_181.jdk/Contents/Home/lib/javafx-mx.jar:/Library/Java/JavaVirtualMachines/jdk1.8.0_181.jdk/Contents/Home/lib/jconsole.jar:/Library/Java/JavaVirtualMachines/jdk1.8.0_181.jdk/Contents/Home/lib/packager.jar:/Library/Java/JavaVirtualMachines/jdk1.8.0_181.jdk/Contents/Home/lib/sa-jdi.jar:/Library/Java/JavaVirtualMachines/jdk1.8.0_181.jdk/Contents/Home/lib/tools.jar:/Users/jiangtao/java/IdeaProjects/demo/target/classes:/Users/jiangtao/java/mavenrepository/org/springframework/boot/spring-boot-starter-web/2.2.6.RELEASE/spring-boot-starter-web-2.2.6.RELEASE.jar:/Users/jiangtao/java/mavenrepository/org/springframework/boot/spring-boot-starter/2.2.6.RELEASE/spring-boot-starter-2.2.6.RELEASE.jar:/Users/jiangtao/java/mavenrepository/org/springframework/boot/spring-boot/2.2.6.RELEASE/spring-boot-2.2.6.RELEASE.jar:/Users/jiangtao/java/mavenrepository/org/springframework/boot/spring-boot-autoconfigure/2.2.6.RELEASE/spring-boot-autoconfigure-2.2.6.RELEASE.jar:/Users/jiangtao/java/mavenrepository/org/springframework/boot/spring-boot-starter-logging/2.2.6.RELEASE/spring-boot-starter-logging-2.2.6.RELEASE.jar:/Users/jiangtao/java/mavenrepository/ch/qos/logback/logback-classic/1.2.3/logback-classic-1.2.3.jar:/Users/jiangtao/java/mavenrepository/ch/qos/logback/logback-core/1.2.3/logback-core-1.2.3.jar:/Users/jiangtao/java/mavenrepository/org/apache/logging/log4j/log4j-to-slf4j/2.12.1/log4j-to-slf4j-2.12.1.jar:/Users/jiangtao/java/mavenrepository/org/apache/logging/log4j/log4j-api/2.12.1/log4j-api-2.12.1.jar:/Users/jiangtao/java/mavenrepository/org/slf4j/jul-to-slf4j/1.7.30/jul-to-slf4j-1.7.30.jar:/Users/jiangtao/java/mavenrepository/jakarta/annotation/jakarta.annotation-api/1.3.5/jakarta.annotation-api-1.3.5.jar:/Users/jiangtao/java/mavenrepository/org/yaml/snakeyaml/1.25/snakeyaml-1.25.jar:/Users/jiangtao/java/mavenrepository/org/springframework/boot/spring-boot-starter-json/2.2.6.RELEASE/spring-boot-starter-json-2.2.6.RELEASE.jar:/Users/jiangtao/java/mavenrepository/com/fasterxml/jackson/core/jackson-databind/2.10.3/jackson-databind-2.10.3.jar:/Users/jiangtao/java/mavenrepository/com/fasterxml/jackson/core/jackson-annotations/2.10.3/jackson-annotations-2.10.3.jar:/Users/jiangtao/java/mavenrepository/com/fasterxml/jackson/core/jackson-core/2.10.3/jackson-core-2.10.3.jar:/Users/jiangtao/java/mavenrepository/com/fasterxml/jackson/datatype/jackson-datatype-jdk8/2.10.3/jackson-datatype-jdk8-2.10.3.jar:/Users/jiangtao/java/mavenrepository/com/fasterxml/jackson/datatype/jackson-datatype-jsr310/2.10.3/jackson-datatype-jsr310-2.10.3.jar:/Users/jiangtao/java/mavenrepository/com/fasterxml/jackson/module/jackson-module-parameter-names/2.10.3/jackson-module-parameter-names-2.10.3.jar:/Users/jiangtao/java/mavenrepository/org/springframework/boot/spring-boot-starter-tomcat/2.2.6.RELEASE/spring-boot-starter-tomcat-2.2.6.RELEASE.jar:/Users/jiangtao/java/mavenrepository/org/apache/tomcat/embed/tomcat-embed-core/9.0.33/tomcat-embed-core-9.0.33.jar:/Users/jiangtao/java/mavenrepository/org/apache/tomcat/embed/tomcat-embed-el/9.0.33/tomcat-embed-el-9.0.33.jar:/Users/jiangtao/java/mavenrepository/org/apache/tomcat/embed/tomcat-embed-websocket/9.0.33/tomcat-embed-websocket-9.0.33.jar:/Users/jiangtao/java/mavenrepository/org/springframework/boot/spring-boot-starter-validation/2.2.6.RELEASE/spring-boot-starter-validation-2.2.6.RELEASE.jar:/Users/jiangtao/java/mavenrepository/jakarta/validation/jakarta.validation-api/2.0.2/jakarta.validation-api-2.0.2.jar:/Users/jiangtao/java/mavenrepository/org/hibernate/validator/hibernate-validator/6.0.18.Final/hibernate-validator-6.0.18.Final.jar:/Users/jiangtao/java/mavenrepository/org/jboss/logging/jboss-logging/3.4.1.Final/jboss-logging-3.4.1.Final.jar:/Users/jiangtao/java/mavenrepository/com/fasterxml/classmate/1.5.1/classmate-1.5.1.jar:/Users/jiangtao/java/mavenrepository/org/springframework/spring-web/5.2.5.RELEASE/spring-web-5.2.5.RELEASE.jar:/Users/jiangtao/java/mavenrepository/org/springframework/spring-beans/5.2.5.RELEASE/spring-beans-5.2.5.RELEASE.jar:/Users/jiangtao/java/mavenrepository/org/springframework/spring-webmvc/5.2.5.RELEASE/spring-webmvc-5.2.5.RELEASE.jar:/Users/jiangtao/java/mavenrepository/org/springframework/spring-aop/5.2.5.RELEASE/spring-aop-5.2.5.RELEASE.jar:/Users/jiangtao/java/mavenrepository/org/springframework/spring-context/5.2.5.RELEASE/spring-context-5.2.5.RELEASE.jar:/Users/jiangtao/java/mavenrepository/org/springframework/spring-expression/5.2.5.RELEASE/spring-expression-5.2.5.RELEASE.jar:/Users/jiangtao/java/mavenrepository/org/slf4j/slf4j-api/1.7.30/slf4j-api-1.7.30.jar:/Users/jiangtao/java/mavenrepository/org/springframework/spring-core/5.2.5.RELEASE/spring-core-5.2.5.RELEASE.jar:/Users/jiangtao/java/mavenrepository/org/springframework/spring-jcl/5.2.5.RELEASE/spring-jcl-5.2.5.RELEASE.jar com.example.demo.Demo01
    ----------------调用方法前----------------
    a:aaaa
    b:0
    c:2000000
    d:34.8888
    e:false
    f:f
    map:{}
    list:[]
    ----------------调用方法前----------------
    ----------------调用方法后----------------
    a:aaaa
    b:0
    c:2000000
    d:34.8888
    e:false
    f:f
    map:{a1=4444, a2=fffff}
    list:[list1, list2, list3]
    ----------------调用方法后----------------
    
    Process finished with exit code 0

此时我们在main方法中调用这个方法后，再输出这些参数，发现，有的参数变了，有的没变。

那我们来看一下，那些变了，Map和List 变了。哪些没变，String, int, long, double, boolean, char 没变。那是什么原因呢？

我们来看，变了的是啥，变了的都是引用数据类型的，也就是说是对象，那么为什么引用数据类型再一个方法中修改之后，即使没有返回值也会变呢？我们知道参数传递有两种，值传递和引用传递，引用数据类型就是引用传递，传递过去的是一个对象的引用地址，在方法内部对这个对象的引用地址的数据进行了修改，那么在方法外部，获得的这个对象的引用地址的数据也会发生变化，这就是原因。而如果是基本类型就是值传递，传进去什么就是什么，在方法内部进行修改以后，没有返回值，在方法外部依然是原来的值，没有改变原来的值，这就是原因。

之后我们家上包装器类型Integer后,来看一下效果：

package com.example.demo;
    
    import java.util.ArrayList;
    import java.util.HashMap;
    import java.util.List;
    import java.util.Map;
    
    public class Demo01 {
    
        public static void main(String[] args) {
            String a = "aaaa";
            int b = 0;
            long c = 2000000l;
            double d = 34.8888;
            boolean e = false;
            char f = 'f';
            Integer g = new Integer(44);
            Map map = new HashMap();
            List list = new ArrayList();
            System.out.println("----------------调用方法前----------------");
    
            System.out.println("a:"+a);
            System.out.println("b:"+b);
            System.out.println("c:"+c);
            System.out.println("d:"+d);
            System.out.println("e:"+e);
            System.out.println("f:"+f);
            System.out.println("g:"+g);
            System.out.println("map:"+map);
            System.out.println("list:"+list);
    
            method(a, b, c, d, e, f, g, map, list);
    
            System.out.println("----------------调用方法前----------------");
    
            System.out.println("----------------调用方法后----------------");
            System.out.println("a:"+a);
            System.out.println("b:"+b);
            System.out.println("c:"+c);
            System.out.println("d:"+d);
            System.out.println("e:"+e);
            System.out.println("f:"+f);
            System.out.println("g:"+g);
            System.out.println("map:"+map.toString());
            System.out.println("list:"+list.toString());
            System.out.println("----------------调用方法后----------------");
        }
    
        private static void method(String a, int b, long c, double d, boolean e, char f, Integer g, Map map, List list){
            a = "bbbbbb";
            b = 1;
            c = 100000000l;
            d = -334.33333;
            e = true;
            f = 't';
            g = new Integer(90000);
            map.put("a1", "4444");
            map.put("a2", "fffff");
            list.add("list1");
            list.add("list2");
            list.add("list3");
        }
    
    }

运行结果：

/Library/Java/JavaVirtualMachines/jdk1.8.0_181.jdk/Contents/Home/bin/java "-javaagent:/Applications/IntelliJ IDEA.app/Contents/lib/idea_rt.jar=65253:/Applications/IntelliJ IDEA.app/Contents/bin" -Dfile.encoding=UTF-8 -classpath /Library/Java/JavaVirtualMachines/jdk1.8.0_181.jdk/Contents/Home/jre/lib/charsets.jar:/Library/Java/JavaVirtualMachines/jdk1.8.0_181.jdk/Contents/Home/jre/lib/deploy.jar:/Library/Java/JavaVirtualMachines/jdk1.8.0_181.jdk/Contents/Home/jre/lib/ext/cldrdata.jar:/Library/Java/JavaVirtualMachines/jdk1.8.0_181.jdk/Contents/Home/jre/lib/ext/dnsns.jar:/Library/Java/JavaVirtualMachines/jdk1.8.0_181.jdk/Contents/Home/jre/lib/ext/jaccess.jar:/Library/Java/JavaVirtualMachines/jdk1.8.0_181.jdk/Contents/Home/jre/lib/ext/jfxrt.jar:/Library/Java/JavaVirtualMachines/jdk1.8.0_181.jdk/Contents/Home/jre/lib/ext/localedata.jar:/Library/Java/JavaVirtualMachines/jdk1.8.0_181.jdk/Contents/Home/jre/lib/ext/nashorn.jar:/Library/Java/JavaVirtualMachines/jdk1.8.0_181.jdk/Contents/Home/jre/lib/ext/sunec.jar:/Library/Java/JavaVirtualMachines/jdk1.8.0_181.jdk/Contents/Home/jre/lib/ext/sunjce_provider.jar:/Library/Java/JavaVirtualMachines/jdk1.8.0_181.jdk/Contents/Home/jre/lib/ext/sunpkcs11.jar:/Library/Java/JavaVirtualMachines/jdk1.8.0_181.jdk/Contents/Home/jre/lib/ext/zipfs.jar:/Library/Java/JavaVirtualMachines/jdk1.8.0_181.jdk/Contents/Home/jre/lib/javaws.jar:/Library/Java/JavaVirtualMachines/jdk1.8.0_181.jdk/Contents/Home/jre/lib/jce.jar:/Library/Java/JavaVirtualMachines/jdk1.8.0_181.jdk/Contents/Home/jre/lib/jfr.jar:/Library/Java/JavaVirtualMachines/jdk1.8.0_181.jdk/Contents/Home/jre/lib/jfxswt.jar:/Library/Java/JavaVirtualMachines/jdk1.8.0_181.jdk/Contents/Home/jre/lib/jsse.jar:/Library/Java/JavaVirtualMachines/jdk1.8.0_181.jdk/Contents/Home/jre/lib/management-agent.jar:/Library/Java/JavaVirtualMachines/jdk1.8.0_181.jdk/Contents/Home/jre/lib/plugin.jar:/Library/Java/JavaVirtualMachines/jdk1.8.0_181.jdk/Contents/Home/jre/lib/resources.jar:/Library/Java/JavaVirtualMachines/jdk1.8.0_181.jdk/Contents/Home/jre/lib/rt.jar:/Library/Java/JavaVirtualMachines/jdk1.8.0_181.jdk/Contents/Home/lib/ant-javafx.jar:/Library/Java/JavaVirtualMachines/jdk1.8.0_181.jdk/Contents/Home/lib/dt.jar:/Library/Java/JavaVirtualMachines/jdk1.8.0_181.jdk/Contents/Home/lib/javafx-mx.jar:/Library/Java/JavaVirtualMachines/jdk1.8.0_181.jdk/Contents/Home/lib/jconsole.jar:/Library/Java/JavaVirtualMachines/jdk1.8.0_181.jdk/Contents/Home/lib/packager.jar:/Library/Java/JavaVirtualMachines/jdk1.8.0_181.jdk/Contents/Home/lib/sa-jdi.jar:/Library/Java/JavaVirtualMachines/jdk1.8.0_181.jdk/Contents/Home/lib/tools.jar:/Users/jiangtao/java/IdeaProjects/demo/target/classes:/Users/jiangtao/java/mavenrepository/org/springframework/boot/spring-boot-starter-web/2.2.6.RELEASE/spring-boot-starter-web-2.2.6.RELEASE.jar:/Users/jiangtao/java/mavenrepository/org/springframework/boot/spring-boot-starter/2.2.6.RELEASE/spring-boot-starter-2.2.6.RELEASE.jar:/Users/jiangtao/java/mavenrepository/org/springframework/boot/spring-boot/2.2.6.RELEASE/spring-boot-2.2.6.RELEASE.jar:/Users/jiangtao/java/mavenrepository/org/springframework/boot/spring-boot-autoconfigure/2.2.6.RELEASE/spring-boot-autoconfigure-2.2.6.RELEASE.jar:/Users/jiangtao/java/mavenrepository/org/springframework/boot/spring-boot-starter-logging/2.2.6.RELEASE/spring-boot-starter-logging-2.2.6.RELEASE.jar:/Users/jiangtao/java/mavenrepository/ch/qos/logback/logback-classic/1.2.3/logback-classic-1.2.3.jar:/Users/jiangtao/java/mavenrepository/ch/qos/logback/logback-core/1.2.3/logback-core-1.2.3.jar:/Users/jiangtao/java/mavenrepository/org/apache/logging/log4j/log4j-to-slf4j/2.12.1/log4j-to-slf4j-2.12.1.jar:/Users/jiangtao/java/mavenrepository/org/apache/logging/log4j/log4j-api/2.12.1/log4j-api-2.12.1.jar:/Users/jiangtao/java/mavenrepository/org/slf4j/jul-to-slf4j/1.7.30/jul-to-slf4j-1.7.30.jar:/Users/jiangtao/java/mavenrepository/jakarta/annotation/jakarta.annotation-api/1.3.5/jakarta.annotation-api-1.3.5.jar:/Users/jiangtao/java/mavenrepository/org/yaml/snakeyaml/1.25/snakeyaml-1.25.jar:/Users/jiangtao/java/mavenrepository/org/springframework/boot/spring-boot-starter-json/2.2.6.RELEASE/spring-boot-starter-json-2.2.6.RELEASE.jar:/Users/jiangtao/java/mavenrepository/com/fasterxml/jackson/core/jackson-databind/2.10.3/jackson-databind-2.10.3.jar:/Users/jiangtao/java/mavenrepository/com/fasterxml/jackson/core/jackson-annotations/2.10.3/jackson-annotations-2.10.3.jar:/Users/jiangtao/java/mavenrepository/com/fasterxml/jackson/core/jackson-core/2.10.3/jackson-core-2.10.3.jar:/Users/jiangtao/java/mavenrepository/com/fasterxml/jackson/datatype/jackson-datatype-jdk8/2.10.3/jackson-datatype-jdk8-2.10.3.jar:/Users/jiangtao/java/mavenrepository/com/fasterxml/jackson/datatype/jackson-datatype-jsr310/2.10.3/jackson-datatype-jsr310-2.10.3.jar:/Users/jiangtao/java/mavenrepository/com/fasterxml/jackson/module/jackson-module-parameter-names/2.10.3/jackson-module-parameter-names-2.10.3.jar:/Users/jiangtao/java/mavenrepository/org/springframework/boot/spring-boot-starter-tomcat/2.2.6.RELEASE/spring-boot-starter-tomcat-2.2.6.RELEASE.jar:/Users/jiangtao/java/mavenrepository/org/apache/tomcat/embed/tomcat-embed-core/9.0.33/tomcat-embed-core-9.0.33.jar:/Users/jiangtao/java/mavenrepository/org/apache/tomcat/embed/tomcat-embed-el/9.0.33/tomcat-embed-el-9.0.33.jar:/Users/jiangtao/java/mavenrepository/org/apache/tomcat/embed/tomcat-embed-websocket/9.0.33/tomcat-embed-websocket-9.0.33.jar:/Users/jiangtao/java/mavenrepository/org/springframework/boot/spring-boot-starter-validation/2.2.6.RELEASE/spring-boot-starter-validation-2.2.6.RELEASE.jar:/Users/jiangtao/java/mavenrepository/jakarta/validation/jakarta.validation-api/2.0.2/jakarta.validation-api-2.0.2.jar:/Users/jiangtao/java/mavenrepository/org/hibernate/validator/hibernate-validator/6.0.18.Final/hibernate-validator-6.0.18.Final.jar:/Users/jiangtao/java/mavenrepository/org/jboss/logging/jboss-logging/3.4.1.Final/jboss-logging-3.4.1.Final.jar:/Users/jiangtao/java/mavenrepository/com/fasterxml/classmate/1.5.1/classmate-1.5.1.jar:/Users/jiangtao/java/mavenrepository/org/springframework/spring-web/5.2.5.RELEASE/spring-web-5.2.5.RELEASE.jar:/Users/jiangtao/java/mavenrepository/org/springframework/spring-beans/5.2.5.RELEASE/spring-beans-5.2.5.RELEASE.jar:/Users/jiangtao/java/mavenrepository/org/springframework/spring-webmvc/5.2.5.RELEASE/spring-webmvc-5.2.5.RELEASE.jar:/Users/jiangtao/java/mavenrepository/org/springframework/spring-aop/5.2.5.RELEASE/spring-aop-5.2.5.RELEASE.jar:/Users/jiangtao/java/mavenrepository/org/springframework/spring-context/5.2.5.RELEASE/spring-context-5.2.5.RELEASE.jar:/Users/jiangtao/java/mavenrepository/org/springframework/spring-expression/5.2.5.RELEASE/spring-expression-5.2.5.RELEASE.jar:/Users/jiangtao/java/mavenrepository/org/slf4j/slf4j-api/1.7.30/slf4j-api-1.7.30.jar:/Users/jiangtao/java/mavenrepository/org/springframework/spring-core/5.2.5.RELEASE/spring-core-5.2.5.RELEASE.jar:/Users/jiangtao/java/mavenrepository/org/springframework/spring-jcl/5.2.5.RELEASE/spring-jcl-5.2.5.RELEASE.jar com.example.demo.Demo01
    ----------------调用方法前----------------
    a:aaaa
    b:0
    c:2000000
    d:34.8888
    e:false
    f:f
    g:44
    map:{}
    list:[]
    ----------------调用方法前----------------
    ----------------调用方法后----------------
    a:aaaa
    b:0
    c:2000000
    d:34.8888
    e:false
    f:f
    g:44
    map:{a1=4444, a2=fffff}
    list:[list1, list2, list3]
    ----------------调用方法后----------------
    
    Process finished with exit code 0

g是Integer 类型，你品，你细品，Integer 也没有变化

不积跬步，无以至千里

不积小流，无以成江海