函数语法

.gitignore

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+# use glob syntax.
+syntax: glob
+*.ser
+*.class
+*~
+*.bak
+#*.off
+*.old
+
+# eclipse conf file
+.settings
+.classpath
+.project
+.manager
+.scala_dependencies
+
+# idea
+.idea
+*.iml
+
+# building
+target
+build
+null
+tmp*
+temp*
+dist
+test-output
+build.log
+
+# other scm
+.svn
+.CVS
+.hg*
+
+# switch to regexp syntax.
+#  syntax: regexp
+#  ^\.pc/
+
+#SHITTY output not in target directory
+build.log

pom.xml

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+<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/maven-v4_0_0.xsd">
+  <modelVersion>4.0.0</modelVersion>
+  <groupId>top.fjy8018</groupId>
+  <artifactId>helloscala</artifactId>
+  <version>1.0-SNAPSHOT</version>
+  <name>${project.artifactId}</name>
+  <description>My wonderfull scala app</description>
+  <inceptionYear>2010</inceptionYear>
+  <licenses>
+    <license>
+      <name>My License</name>
+      <url>http://....</url>
+      <distribution>repo</distribution>
+    </license>
+  </licenses>
+
+  <properties>
+    <maven.compiler.source>1.8</maven.compiler.source>
+    <maven.compiler.target>1.8</maven.compiler.target>
+    <encoding>UTF-8</encoding>
+    <scala.version>2.11.8</scala.version>
+  </properties>
+
+  <dependencies>
+    <dependency>
+      <groupId>org.scala-lang</groupId>
+      <artifactId>scala-library</artifactId>
+      <version>${scala.version}</version>
+    </dependency>
+  </dependencies>
+
+  <build>
+    <sourceDirectory>src/main/scala</sourceDirectory>
+    <testSourceDirectory>src/test/scala</testSourceDirectory>
+    <plugins>
+      <plugin>
+        <groupId>org.scala-tools</groupId>
+        <artifactId>maven-scala-plugin</artifactId>
+        <version>2.15.0</version>
+        <executions>
+          <execution>
+            <goals>
+              <goal>compile</goal>
+              <goal>testCompile</goal>
+            </goals>
+            <configuration>
+              <args>
+                <arg>-make:transitive</arg>
+                <arg>-dependencyfile</arg>
+                <arg>${project.build.directory}/.scala_dependencies</arg>
+              </args>
+            </configuration>
+          </execution>
+        </executions>
+      </plugin>
+      <plugin>
+        <groupId>org.apache.maven.plugins</groupId>
+        <artifactId>maven-surefire-plugin</artifactId>
+        <version>2.6</version>
+        <configuration>
+          <useFile>false</useFile>
+          <disableXmlReport>true</disableXmlReport>
+          <!-- If you have classpath issue like NoDefClassError,... -->
+          <!-- useManifestOnlyJar>false</useManifestOnlyJar -->
+          <includes>
+            <include>**/*Test.*</include>
+            <include>**/*Suite.*</include>
+          </includes>
+        </configuration>
+      </plugin>
+    </plugins>
+  </build>
+</project>

src/main/scala/top/fjy8018/App.scala

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+package top.fjy8018
+
+/**
+ * @author ${user.name}
+ */
+object App {
+  
+  def foo(x : Array[String]) = x.foldLeft("")((a,b) => a + b)
+  
+  def main(args : Array[String]) {
+    println( "Hello World!" )
+    println("concat arguments = " + foo(args))
+  }
+
+}

src/main/scala/top/fjy8018/scala/FunctionApp.scala

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+package top.fjy8018.scala
+
+/**
+  * F嘉阳
+  * 2018-11-25 20:21
+  */
+object FunctionApp {
+  def main(args: Array[String]): Unit = {
+    println(add(1,2))
+
+    println(sum(3,4))
+
+    // 调用无参方法可以不加括号
+    printHello
+  }
+
+  def add(x:Int,y:Int):Int={
+    // 函数最后一行为返回值
+    x+y
+  }
+
+  /**
+    * 函数体只有一行可以省略括号，返回值scala会自动进行类型推断
+    * @param x
+    * @param y
+    * @return
+    */
+  def sum(x:Int,y:Int)= x + y
+
+  def printHello()= println("Hello world!")
+
+}

src/main/scala/top/fjy8018/scala/HelloWorld.scala

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+package top.fjy8018.scala
+
+object HelloWorld {
+  def main(args: Array[String]): Unit = {
+    println("Hello world")
+  }
+}