Flex入门Flex基本语法

1 Flex 变量

   var v1:int = 9; //int v1 = 9;
          var v2:uint = 10;
          var v3:Boolean = true;
          var v4:Number = 4.5;
          var v5:String = "HelloWorld";
          var v6:String = 'HelloWorld Again';
          var v7:* = 3;  //*类型：任意数据类型
          trace(v7);
          v7 = 'hello';
          trace(v7);
          var v8;      //v8只定义没赋值，为undefined
          trace("v8=",v8);
          var v9:String;
          trace(v9);  //String 类似java中的null
          var v10:Array = [2, 3, 4, 5]; //数组
          trace(v10);
          var v11:Object = {id:3, name:"zhangsan",age:18};                                                                                                                                                                                                                   //map v11是个对象类型，写了个大括号，里面是属性-值格式，类似json，或者叫关联性数组。
          trace(v11.name);
Flex中定义变量的格式为: var name:type [ = initvalue]

2 Flex中语句

var v1:Array = ["a", "b", "c", "d"];
for(var i:String in v1) {
    //trace(i); // 0 1 2 3
    trace(v1[i]); // a b c d
}

for each (var propertyValue:String in v1) {
    trace(propertyValue);// a b c d
}

var v2:Object = {id:1, name:'lisi', age:19};
for(var i in v2) {
    trace(i);        //name id age
    trace(v2[i]);    //lisi 1 19
}

for each (var propertyValue in v2) {
    trace(propertyValue);     //lisi 1 19
}

trace(v2["name"]);            //lisi

语句中的for var i 是map中的key-value的key，而arr[i]指的是value，

for each是取出value。

3 函数

public function AS_0400_Functions()

{
    //声明一个匿名函数类型变量traceParameter，定义在后面
    var traceParameter:Function = function   (aParam:String) :void//void f(String aParam)
    {
        trace(aParam);
    };
    traceParameter("hello"); // hello


    var traceArray:Array = new Array(); //定义一个数组
    //数组的0号位置存储了一个函数变量，匿名函数变量，带一个String类型参数
    traceArray[0] = function (aParam:String):void
    {
        trace(aParam);
    };
    traceArray[0]("hello");

    f();
    f('lisi');

    f2(1, 3, 5, 4, 6, 8);

    var arr : Array = ["hello world!","syx",19];
    say(arr,"test",[1,2,2]);
}
//函数可以有默认参数值
public function f(name:String = 'zhangsan') : void {
    trace(name);
}

//函数可以有变参
//args 是一个存储Object类型的数组
public function f2(...args): void {

    trace(args.length);
    for each(var value:String in args) {
        trace(value);
    }
}

public function say(...args): void {
    var strTemp : String = "";
    for each(var value : String in args) {
        strTemp += value + ":";
    }
    trace(strTemp);
}

4 Flex中面向对象思想

入口：

      var s:Student = new Student();//定义对象
      trace(s.name);//zhangsan
      var t:Teacher = new Teacher();
      t.f = function() {//给t增加一个函数
            trace("f");
      }
      t.f();// f
      delete t.f;
      var f:IFlyable = new T();
      t.f();  // TypeError: Error #1006: f 不是函数。

类：

package com.syx.flex.test{
      public class Student{
            private var _name:String = 'zhangsan';
            public function Student() {}
            public function set name(name:String) : void { //setName
            this._name = name;
      }

      public function get name():String {
            return this._name;
      }
}

接口：

package com.syx.flex.test{
      public interface IFlyable {
            function fly():void;
      }
}

实现：

package com.syx.flex.test{
      public class Bird implements IFlyable  {
            public function Bird()  {

            }

            public function fly():void {
                  trace("bird fly!");
            }
      }

}

多态：

      var f:IFlyable = new Bird();

      f.fly();

5 简单字符串处理

var s:String = "syx";
for(var i:int=0; i<s.length; i+=1) {
      trace(s.charAt(i), s.charCodeAt(i) );
}
trace(s.concat(" hellow", " world"));
trace(s.toUpperCase());

6 数组

var a1 : Array = [1, 2, 3];
var a2 : Array = ["a", "b", "c"];
var a3 : Array = new Array();
trace(a3.push("one"));//1
trace(a3.push("two"));//2
trace(a3.push("three"));//3
trace(a3);//one,two,three
var a4 : Array = new Array(3);
trace(a4.length);//3
trace(a4[0]);//undefined
var a5 : Array = new Array('zhangsan', 'lisi', 'wangwu');
a5.unshift('zhaoliu');
trace(a5);//zhaoliu,zhangsan,lisi,wangwu
//function splice(startIndex:int, deleteCount:uint, ... values):Array
a5.splice(1, 0, 'sunqi', 'liuba');
//删除1位置后0个元素（包括1），在插入...args
trace(a5);//zhaoliu,sunqi,liuba,zhangsan,lisi,wangwu
a5.splice(1, 2);
trace(a5);//zhaoliu,zhangsan,lisi,wangwu
//Removes the last element from an array and returns the value of that element
a5.pop();
//Removes the first element from an array and returns that element.
a5.shift();
delete a5[0]; //a5[0] = 'undefined'
trace(a5[0]);//undefined
//Reverses(逆序) the array in place
a5.reverse();
//Sorts the elements in an array. This method sorts according to 
//Unicode values. (ASCII is a subset of Unicode.) 
a5.sort();
a5.sort(Array.CASEINSENSITIVE);
a5.sort(Array.DESCENDING | Array.CASEINSENSITIVE );

var poets:Array = new Array();
poets.push({name:"Angelou", born:"1928"});
poets.push({name:"Blake", born:"1757"});
poets.push({name:"cummings", born:"1894"});
poets.push({name:"Dante", born:"1265"});
poets.push({name:"Wang", born:"701"});
poets.sortOn("born", Array.NUMERIC);

7 异常处理

var a :Array = [1, 2, 3];
try {
      throw new EOFError("error occur");
} catch (error:EOFError) {
     trace(error);
} finally {
     trace("finally");
}