How to add the function of sending free SMS to Android system?

First, you should add the permission to send SMS to the program manifest file AndroidManifest.xml

& ltuses-permission Android:name = " Android . permission . send _ SMS "/& gt；

Includes two TextView components, two EditText components and a Button component, and adds a click event on the send button in the main program.

Private EditText txt _ num

Private EditText txt _ content

public void on create(Bundle saved instancestate){

super . oncreate(savedInstanceState)；

setContentView(r . layout . main)；

txt _ num =(EditText)this . findviewbyid(r . id . txt _ num)；

txt _ content =(EditText)this . findviewbyid(r . id . txt _ content)；

Button BTN _ send =(Button)this . findviewbyid(r . id . BTN _ send)；

BTN _ send . setonclicklistener(new OnClickListener(){

Public void onClick (view v)

String str_num = txt_num.getText()。 toString()； //Get the phone number

string str _ content = txt _ content . gettext()。 toString()； //Get the short message content

SMS manager manager _ SMS = SMS manager . get default()； //Get the SMS Manager.

//Because the message may be longer, split the message.

ArrayList & lt string & gt texts = SMS manager. Divide message (str _ content);

For (string text: text) (

SMS manager . sendtextmessage(str _ num，null，text，null，null)； //Send each message separately.

}

Toast. Maketext (SMS activity. This, "sent successfully!" , toast. Length _ length). show()； //Prompt success

}

});

}

At this point, the function of sending SMS has been introduced.