Tiger学习 之 parameterized type 参数<generic>

本文详细介绍了Java中泛型的使用方法,包括如何正确地参数化集合类型如List和Map,如何避免ClassCastException异常,以及如何处理1.5版本的语法警告等问题。
方法的参数化...看代码

1->方法参数
[quote]

List list = new ArrayList();
list.add("Hello");
list.add("World");
setList(list);

public static void setList[color=blue](List<String> list[/color]) {
[color=blue]//确保值能传入参数化相同的对象的List,或没有参数化的List [/color]
}
[/quote]
List list = new ArrayList(); 可以嘛?可以,但是,小心会有在运行是出现java.lang.ClassCastException 异常...应该写成List<String> list = new ArrayList<String>();

2>方法的返回
[quote]
public static List<String> getList() {
List<String> list = new ArrayList<String>();
list.add("Hello");
list.add("World");
return list;
}

List<String> List1 = getList();

[/quote]

3->参数化参数
[quote]
Map<String,[color=blue] List<String>[/color]> map = new Map<String, List<String>>();
[color=blue] //还可以继续尖括号下去,只是取值麻烦,不过取值都是自己拆箱的,无需转换[/color]
[/quote]

4->Lint(1.5语法警告)
Eclipse会自动提醒的...或者,在编译时加入 -source 1.5
The type MysqlxCrud.Collection is not generic; it cannot be parameterized with arguments <? extends GrantedAuthority> <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>KuCun2</groupId> <artifactId>KuCun2</artifactId> <version>0.0.1-SNAPSHOT</version> <packaging>war</packaging> <name>KuCun2</name> <description/> <parent> <groupId>org.springframework.boot</groupId> <artifactId>spring-boot-starter-parent</artifactId> <version>2.3.12.RELEASE</version> <!-- 请根据需要选择版本 --> <relativePath/> <!-- lookup parent from repository --> </parent> <properties> <webVersion>4.0</webVersion> <project.build.sourceEncoding>UTF-8</project.build.sourceEncoding> <protobuf.version>3.21.12</protobuf.version> </properties> <dependencies> <dependency> <groupId>javax</groupId> <artifactId>javaee-api</artifactId> <version>8.0</version> <scope>provided</scope> </dependency> <dependency> <groupId>org.glassfish.web</groupId> <artifactId>javax.servlet.jsp.jstl</artifactId> <version>1.2.4</version> </dependency> <!-- Spring Boot Starter Data JPA --> <dependency> <groupId>org.springframework.boot</groupId> <artifactId>spring-boot-starter-data-jpa</artifactId> </dependency> <!-- MySQL Connector --> <dependency> <groupId>mysql</groupId> <artifactId>mysql-connector-java</artifactId> </dependency> <!-- Optional: Lombok for reducing boilerplate code --> <dependency> <groupId>org.projectlombok</groupId> <artifactId>lombok</artifactId> <optional>true</optional> </dependency> <dependency> <groupId>org.springframework.boot</groupId> <artifactId>spring-boot-starter-web</artifactId> </dependency> <dependency> <groupId>org.springframework</groupId> <artifactId>spring-webmvc</artifactId> </dependency> <dependency> <groupId>org.springframework.boot</groupId> <artifactId>spring-boot-starter-web</artifactId> <exclusions> <exclusion> <groupId>org.springframework.boot</groupId> <artifactId>spring-boot-starter-tomcat</artifactId> </exclusion> </exclusions> </dependency> <dependency> <groupId>org.springframework.boot</groupId> <artifactId>spring-boot-starter-tomcat</artifactId> <scope>provided</scope> </dependency> <dependency> <groupId>org.springframework.boot</groupId> <artifactId>spring-boot-starter-web</artifactId> <exclusions> <exclusion> <groupId>com.fasterxml.jackson.datatype</groupId> <artifactId>jackson-datatype-jsr310</artifactId> </exclusion> </exclusions> </dependency> <dependency> <groupId>com.fasterxml.jackson.datatype</groupId> <artifactId>jackson-datatype-jsr310</artifactId> </dependency> <!-- Jackson Databind --> <dependency> <groupId>com.fasterxml.jackson.core</groupId> <artifactId>jackson-databind</artifactId> </dependency> <!-- Jackson Core --> <dependency> <groupId>com.fasterxml.jackson.core</groupId> <artifactId>jackson-core</artifactId> </dependency> <!-- Jackson Annotations --> <dependency> <groupId>com.fasterxml.jackson.core</groupId> <artifactId>jackson-annotations</artifactId> </dependency> <dependency> <groupId>org.springframework.boot</groupId> <artifactId>spring-boot-starter-security</artifactId> <exclusions> <exclusion> <groupId>com.google.protobuf</groupId> <artifactId>protobuf-java</artifactId> </exclusion> </exclusions> </dependency> <dependency> <groupId>com.google.protobuf</groupId> <artifactId>protobuf-java</artifactId> <version>${protobuf.version}</version> </dependency> </dependencies> <build> <plugins> <plugin> <artifactId>maven-compiler-plugin</artifactId> <version>2.3.2</version> <configuration> <source>1.8</source> <target>1.8</target> <compilerArgs> <arg>-parameters</arg> </compilerArgs> </configuration> </plugin> <plugin> <artifactId>maven-war-plugin</artifactId> <version>2.6</version> <configuration> <failOnMissingWebXml>false</failOnMissingWebXml> </configuration> </plugin> </plugins> </build> </project>
05-28
评论
添加红包

请填写红包祝福语或标题

红包个数最小为10个

红包金额最低5元

当前余额3.43前往充值 >
需支付:10.00
成就一亿技术人!
领取后你会自动成为博主和红包主的粉丝 规则
hope_wisdom
发出的红包
实付
使用余额支付
点击重新获取
扫码支付
钱包余额 0

抵扣说明:

1.余额是钱包充值的虚拟货币,按照1:1的比例进行支付金额的抵扣。
2.余额无法直接购买下载,可以购买VIP、付费专栏及课程。

余额充值