PIXELS AND SCREEN COMPATIBILITY

================================

dp to pixels

• float scale = getResources().getDisplayMetrics().density;
• numPixels = (int) (dp * scale + 0.5f);

ViewConfiguration

• .get(myContext).getScaledTouchSlop()
  • returns int of the distance in pixels a touch
  • can wander before we think the user is scrolling

android.util package

=====================

Log

• log stuff to console
• .i
  • information
• .e
  • error
• .d
  • debug

USER INPUT

=======

Button

• android:onClick- the function to call when button is clicked

• alternative\/\/\/

    .setOnClickListener(new View.onClickListener() {
        @Override
        public void onClick(View v) {
            //do something
        }
    }
  

ImageButton

• a button that can have an image on it
• see Button

CheckBox

• yes/no input
• checkBoxElem.isChecked()
  • to get yes/no

Spinner

• dropdown menu but in popup form
• selection choices are strings in an array in strings.xml
  • see string arrays in strings.xml below
• spinnerElem.getSelectedItem().toString()
  • to get selected item

EditText

• collect text input
• lines- number of lines the textbox will have
• editTextElem.getText().toString()
  • to get entered text

LAYOUT

=======

ScrollView

<ScrollView></ScrollView>

• things inside are scrollable

LinearLayout

• one thing after another

    <LinearLayout>
        <Element/>
        <Element/>
    </LinearLayout>
  

strings.xml

===========

• stores app-wide string values/names

    <string-array name="name">
        <item>@string/stringName</item>
  

  • accessed with @array/name

<color name="white">#FFFFFF</color>

• add color
• can be accessed in code w/ @color/white

METHODS

========

findViewById(int id)

• get an element from the UI
• ex: final EditText nameField = (EditText)findViewById(R.id.EditText’sId);
  • where EditText’sId is found in id=”@+id/EditText’sId”

getBaseContext()

• returns base context (replaces this)

finish()

• sends activity to the background

COMMAND PROMPT

===============

pwd

• get your directory

cd

• go to that directory (follow pwd’s format)

SETUP

=======

git config

• –global
  • change setting on all repos
  • disclusion = only change setting on this repo
• –help
  • get local help page
• user.name [“name”]
  • get/set username
    • (put “name” after if you want to set it)
• user.email [“email”]
  • get/set email
• core.editor [“directory”]
  • get/set default editor to type values in when prompted
  • ex: core.editor “atom –wait”

git init

• creates new git repository
  • first cd to the correct folder
  • if you want to see it, go to file manager, options, show hidden files (roughly)

DOING STUFF

============

git status

• shows status of all files in repo
• untracked- hasn’t been anywhere yet
• unmodified- unchanged from last commit/ from after pulling
• modified- changed, but not set to commit yet
• staged- going to commit soon

git add <filename> [<filename> <filename> ...]

• add file’s content to next commit
  • -start TRACKING that file, STAGE files, mark
    • merge-conflicted files as RESOLVED, etc
• see names of untracked files w/ git status
• ex: git add README
• -s
  • makes output shorter
  • M = modified
  • A = added
  • ?? = not tracked
  • 2 columns of symbols ^^
    • left = staging area status
    • right = working area status git commit
• commits the changes in staging area (see git status)
• w/o -m
  • opens core editor to type message describing commit
  • close core editor window to proceed
• -m
  • type commit message w/o opening core editor
• -a
  • commit everything that was changed (skip staging area)

cat .gitignore <press enter> <what to ignore> <enter> <etc>

• make those files not show up in git status
• • *.[extension] - ignore w/ that extension
  • *[part of name] - ignore w/ that in end of name
  • (note the * in front)
  • disregards lines with # (comment)
• no .a files
  • *.a
• but do track lib.a, even though you’re ignoring .a files above
  • !lib.a
• only ignore the TODO file in the current directory, not subdir/TODO
  • /TODO
• ignore all files in the build/ directory
  • build/
• ignore doc/notes.txt, but not doc/server/arch.txt
  • doc/*.txt
• ignore all .pdf files in the doc/ directory
  • doc/*/.pdf

git diff <filename>

• shows difference between working directory and staging area
  • ex: lines of code that were changed
• if discluded, shows all files i think

git log

• gives list of commits w/ their message

git show <commit>

• display what changed in that commit (git log?)
• can be HEAD => the commit you're currently on

git checkout <commit> <filename>

• restore that file in working directory to that commit’s version

git help <commandName>

• your friend. opens up local help page (html file)

.xml FILE STRUCTURE

<?xml version="1.0" encoding="UTF-8"?>
<firstThing>
    <second attribute="this">actual thing</second>
    <yeah lang="en">alsdkjfa</yeah>
</firstThing>

see https://www.w3schools.com/xml/dom_nodes.asp

HOW TO ACCESS

setup

var xhttp = new XMLHttpRequest();
xhttp.onreadystatechange = function() {
    if (this.readyState == 4 && this.status == 200) {
        myFunction(this);
    }
};
xhttp.open("GET", "books.xml", true);
xhttp.send();

get elements

var xmlDoc = xml.responseXML;
var x = xmlDoc.getElementsByTagName("title");

get value

x[3].childNodes[0].nodeValue;
    ^^ 4th child of doc + the 1st child of that element's value/text

OBJECT DESCRIPTION

XMLHttpRequest
    .open(requestType, url, asynchronous/synchronous)
        requestType- "GET" or "POST"
        url- "http://aldkjfalsd" or "file.xml"
        last boolean- true = asyncrhonous (one thing at a time)
            false = synchronous (all at once/real time)
    .send()
        send the request
    .onreadystatechange (event)
        this.
            readyState
                0- request not intialized
                1- server connection established
                2- request recieved
                3- processing request
                4- request finished and response ready
            status
                200- ok
                404- page not found