actionscript 3 - flash simple button with text -

i have simple button in flash cs5 - as3 called btn1 dynamic text called text_txt inside inside it.

the goal change text however...

btn1.visible=true; // works fine this.btn1.text_txt.text="hello"; // give null error 

my question is: how programatically change text inside button ?

because have flashdevelop can show how programmatically.

if dealing sprite object(which recommend) following how access textfield in sprite object:

var textfield:textfield = new textfield(); textfield.name = "textfield"; textfield.mouseenabled = false;  var rectangleshape:shape = new shape(); rectangleshape.graphics.beginfill(0xff0000); rectangleshape.graphics.drawrect(0, 0, 100, 25); rectangleshape.graphics.endfill();  var buttonsprite:sprite = new sprite(); buttonsprite.addchild(rectangleshape); buttonsprite.addchild(textfield); addchild(buttonsprite);  var tf:textfield = textfield(buttonsprite.getchildbyname("textfield")); tf.text = "button sprite text"; 

first textfield object called textfield instantiated , name property assigned string "textfield" same setting instance name.

next shape object called rectangleshape instantiated graphically configured simple red rectangle.

next sprite display object object called buttonsprite instantiated , textfield , rectangleshape display objects added it. sprite display object container added stage.

finally buttonsprite display object container's getchildbyname() method called , returns textfield display object. the textfield display object's name property has given getchildbyname() methods's argument. next returned textfield object stored in local textfield object called tf gives access textfield.

[update]

the following approach accessing textfield object via simplebutton object similar accessing via sprite object(i don't recommend though):

var textfield:textfield = new textfield(); textfield.name = "textfield"; textfield.mouseenabled = false;  var rectangleshape:shape = new shape(); rectangleshape.graphics.beginfill(0xff0000); rectangleshape.graphics.drawrect(0, 0, 100, 25); rectangleshape.graphics.endfill();  var simplebuttonsprite:sprite = new sprite(); simplebuttonsprite.name = "simplebuttonsprite"; simplebuttonsprite.addchild(rectangleshape); simplebuttonsprite.addchild(textfield);  var simplebutton:simplebutton = new simplebutton(); simplebutton.upstate = simplebuttonsprite; simplebutton.overstate = simplebuttonsprite; simplebutton.downstate = simplebuttonsprite; simplebutton.hitteststate = simplebuttonsprite; addchild(simplebutton);  // local simplebuttonsprite object var sbs:displayobjectcontainer = displayobjectcontainer(simplebutton.upstate); //local textfield object var tf:textfield = textfield(sbs.getchildbyname("textfield"));   tf.text = "simple button text ";