scala 学习笔记(03) 参数缺省值、不定个数参数、类的属性(Property)、泛型初步

/**
* 参数缺省值
* @param person
* @param msg
*/
def saySomething(person: String = "somebody", msg: String = "Hello") = {
println(person + " say : " + msg);
}

saySomething()
saySomething("jimmy")
saySomething("jimmy", "hi")

public void saySomething(String person, String msg) {
Predef..MODULE$.println(new StringBuilder().append(person).append(" say : ").append(msg).toString());
} public String saySomething$default$1() {
return "somebody";
} public String saySomething$default$2() {
return "Hello";
}

/**
* 定义一个带参主构造器的类
* @param pReadOnly
*/
class Sample(pReadOnly: String) { /**
* 可读写的属性
*/
var myProperty: String = _; private val _readOnly: String = pReadOnly; /**
* 只读属性
*/
def readOnly: String = _readOnly;}

val sample = new Sample("test")
println(sample.readOnly)
sample.myProperty = "a new value"
println(sample.myProperty)

public class Sample
{
private String myProperty;
private final String _readOnly; public String myProperty()
{
return this.myProperty; }
public void myProperty_$eq(String x$1) { this.myProperty = x$1; }
private String _readOnly() {
return this._readOnly;
} public String readOnly()
{
return _readOnly();
} public Sample(String pReadOnly)
{
this._readOnly = pReadOnly;
}
}

/**
* 不固定个数的参数
* @param x
* @return
*/
def add(x: Int*) = {
var i = 0
for (j <- x) i += j
i
}

println(add())
println(add(1, 2, 3, 4, 5))

public final class DefHello$$anonfun$add$1 extends AbstractFunction1.mcVI.sp
implements Serializable
{
public static final long serialVersionUID = 0L;
private final IntRef i$1; public final void apply(int j)
{
apply$mcVI$sp(j); }
public void apply$mcVI$sp(int j) { this.i$1.elem += j; } public DefHello$$anonfun$add$1(IntRef i$1)
{
}
}

public void main(String[] args)
{
Predef..MODULE$.println(BoxesRunTime.boxToInteger(add(Nil..MODULE$)));
Predef..MODULE$.println(BoxesRunTime.boxToInteger(add(Predef..MODULE$.wrapIntArray(new int[] { 1, 2, 3, 4, 5 }))));
...
} public int add(Seq<Object> x)
{
IntRef i = IntRef.create(0);
x.foreach(new AbstractFunction1.mcVI.sp() { public static final long serialVersionUID = 0L; public final void apply(int j) { apply$mcVI$sp(j); }
public void apply$mcVI$sp(int j) { DefHello..this.elem += j; } });
return i.elem;
}

public class SampleClass<T> {
private T _t; public SampleClass(T t) {
this._t = t;
} public T getT() {
return _t;
}
}

SampleClass<String>[] objs = new SampleClass<String>[10];

class MyClass[T](t1: T) {
var t: T = t1;
}

val objs = new Array[MyClass[String]](10)
objs(0) = new MyClass[String]("a")
for (x <- objs; if x != null) println(x.t)

MyClass[] objs = new MyClass[10]; objs[0] = new MyClass("a"); Predef..MODULE$.refArrayOps((Object[])objs).withFilter(new DefHello..anonfun.main.1()).foreach(new DefHello..anonfun.main.2());