虎克的Android SDK百科全書: 8月 2013

2013年8月29日星期四

防止鍵盤因為ScrollView上有EditText而自動彈出

修改AndroidManifest.xml，於scroll view對應的activity裡設定windowSoftInputMode

ex:

<activity
android:name=".AddFoodActivity"
android:label="@string/app_name"
android:windowSoftInputMode="stateHidden" >

</activity>

防止表格over scroll時出現藍色線條

listView.setOverScrollMode(View.OVER_SCROLL_NEVER);

基本表格操作

透過ListView顯示表格

1. 新增xml，定義ListView

2. 新增xml，定義表格裡每一行的UI

3. 新增繼承自ArrayAdapter的類別 (.java)
定義getView method。此method將回傳表格每一行的UI

4. 在activity的程式碼裡設定listView的adapter

設定cell的高度
由定義表格裡每一行UI的XML的layout_height決定

更新表格內容
ex:
dataListView.invalidateViews();

2013年8月28日星期三

UI元件的隱藏

設定
呼叫setVisibility
Parameters
visibility One of VISIBLE, INVISIBLE, or GONE.

判斷是否隱藏
呼叫isShown

字串和數字的轉換

int count = Integer.parseInt("100");

float value = Float.parseFloat("100.33");

產生UUID

String uniqueID = UUID.randomUUID().toString();

2013年8月27日星期二

設定action bar

XML

<menu xmlns:android="http://schemas.android.com/apk/res/android" >

<item
android:id="@+id/action_done"
android:showAsAction="always"
android:title="完成"
/>
</menu>

JAVA
@Override
public boolean onCreateOptionsMenu(Menu menu) {
   // Inflate the menu items for use in the action bar
   MenuInflater inflater = getMenuInflater();
   inflater.inflate(R.menu.done, menu);
   return super.onCreateOptionsMenu(menu);
}

button被點選

public boolean onOptionsItemSelected(MenuItem item) {

return true;

}

設定透明顏色

XML:

<ImageButton
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_toRightOf="@+id/addFecesDiarrheaButton"
android:layout_alignBottom="@+id/addFecesCountLabel"
android:src="@drawable/irregularity"
android:background="@android:color/transparent"
/>

JAVA:

addFoodButton.setBackgroundColor(Color.TRANSPARENT);

2013年8月26日星期一

利用picker設定日期和時間

ex:

dateButton.setOnClickListener(new View.OnClickListener() {

@Override
public void onClick(View v) {
// TODO Auto-generated method stub
DatePickerDialog dialog = new DatePickerDialog(AddFecesActivity.this, new DatePickerDialog.OnDateSetListener() {

@Override
public void onDateSet(DatePicker view, int year, int monthOfYear,
int dayOfMonth) {
// TODO Auto-generated method stub
currentTime.set(0, currentTime.minute, currentTime.hour, dayOfMonth,
monthOfYear,year);
String timeStr = currentTime.format("%Y-%m-%d");
dateButton.setText(timeStr);
}
}, currentTime.year, currentTime.month, currentTime.monthDay);
dialog.show();
}
});

timeButton.setOnClickListener(new View.OnClickListener() {

@Override
public void onClick(View v) {
// TODO Auto-generated method stub

TimePickerDialog dialog = new TimePickerDialog(AddFecesActivity.this, new TimePickerDialog.OnTimeSetListener(){
@Override
public void onTimeSet(TimePicker view, int hourOfDay, int minute) {

currentTime.set(0, minute, hourOfDay, currentTime.monthDay,
currentTime.month+1, currentTime.year);
String timeStr = currentTime.format("%H:%M");
timeButton.setText(timeStr);

}

}, currentTime.hour, currentTime.minute,
false);

dialog.show();

}
});

時間轉字串

ex:

Time time = new Time();
time.setToNow();
String str = time.format("%Y-%m-%d %H:%M");

->

2013-08-27 11:31

取得目前時間

Time time = new Time();
time.setToNow();

XML Drawables

Layer List
State List
Level List
TransitionDrawable
InsetDrawable
ClipDrawable
ScaleDrawable
ShapeDrawable

http://www.vogella.com/articles/AndroidDrawables/article.html

9-patch image

http://radleymarx.com/blog/simple-guide-to-9-patch/

http://www.ootpapps.com/2013/02/android-9-patch-imageshow-they-work-and-how-to-create-them/

draw 9 patch image

draw9patch

density

For example, you might decide that your default padding is going to be 16px for XHDPI. That means it will be 12px for HDPI and 8px for MDPI (which is also 8dp). Approach your design with the 2:3:4 ratio in mind; that’s the ratio of MDPI pixels to HDPI pixels to XHDPI pixels

2013年8月25日星期日

fragment

A Fragment represents a behavior or a portion of user interface in an Activity. You can combine multiple fragments in a single activity to build a multi-pane UI and reuse a fragment in multiple activities. You can think of a fragment as a modular section of an activity, which has its own lifecycle, receives its own input events, and which you can add or remove while the activity is running (sort of like a "sub activity" that you can reuse in different activities).

AdapterView

You have a data set, you throw it at an Adapter, and you end up with views in your layout

ex:

ListView

ExpandableListView

group list data by categories. It has the capability of expanding and collapsing the groups when user touches header.

GridView

Spinner

ViewPager

Adapter is the interface that takes a data set and returns views representing that data. The adapter is able to say how many items there are, return an item for a specific position, and return the view associated with a position, among other things. For a ListView, you will use the ListAdapter interface that extends Adapter to add a couple of list-specific methods. Similarly, you will use the SpinnerAdapter interface for use in a Spinner.

gravity and layout_gravity

android:gravity sets the gravity of the content of the View its used on.
android:layout_gravity sets the gravity of the View or Layout in its parent.

ex:

<Button
android:id="@+id/addFoodDateButton"
android:layout_width="140dp"
android:layout_height="40dp"
android:layout_marginTop="12dp"
android:layout_marginLeft="12dp"
android:textColor="#000000"
android:background="@android:color/transparent"
android:layout_toRightOf="@id/addFoodDateTitleImageView"
android:text="2013-09-12"
android:gravity="left|center_vertical"
/>

android:gravity
center_vertical, top , bottom

ex:

calorieTextView.setGravity(Gravity.CENTER);

ViewGroup

the ViewGroup class is for views that can contain one or more child views. ViewGroup provides the standardized methods for these classes to use so that they can perform tasks such as adding, removing, getting, and counting child views.

Iterating through a ViewGroup’s Children
ex:

final int childCount = myViewGroup.getChildCount();
for (int i = 0; i < childCount; i++) {
View v = myViewGroup.getChildAt(i);
// Do something with the View
}

FrameLayout
LinearLayout
RelativeLayout
ListView
GridView
Spinner
ViewPager
AdapterViewAnimator
AdapterViewFlipper
AppWidgetHostView
DialerFilter
FragmentBreadCrumbs
GestureOverlayView
GridLayout
HorizontalScrollView
ImageSwitcher
MediaController
PagerTabStrip
PagerTitleStrip
ScrollView
SearchView
SlidingDrawer
StackView
TabHost
TabWidget
TableLayout
TableRow
TextSwitcher
ViewAnimator
ViewFlipper
ViewSwitcher
ZoomControls

圖片縮放

scaleType

resize bitmap:

int width = 1000;
int height = 500;

Bitmap resizeBitmap = Bitmap.createScaledBitmap(oldBitmap, width, height, true);

JAVA:

categoryButton.setScaleType(ImageView.ScaleType.FIT_XY );

XML:

<ImageButton
android:id="@+id/foodDetailBigBut"
android:layout_width="match_parent"
android:layout_height="match_parent"
android:layout_alignTop="@+id/foodDetailViewPager"
android:layout_alignLeft="@+id/foodDetailViewPager"
android:src="@drawable/bigbut"
android:scaleType="fitXY"
android:background="@android:color/transparent"
/>

維持比例縮放: centerCrop & centerInside
不維持比例，縮放到指定的大小: fitXY

android UI元件基本介紹

TextView: 顯示文字

EditText: 輸入文字

Button: 按鈕

ImageView: 顯示圖片

ImageButton: 顯示圖片的button

CheckBox, RadioButton, Switch , ToggleButton

CalendarView

CheckedTextView

DatePicker

RatingBar

SeekBar

Spinner

TimePicker

AnalogClock

Chronometer

DigitalClock

KeyboardView

MediaRouteButton

QuickContactBadge

ProgressBar

WebView

VideoView

2013年8月23日星期五

split action bar

模擬器的dpi

2013年8月22日星期四

鍵盤(keyboard)樣式

http://developer.android.com/reference/android/widget/TextView.html#attr_android:inputType

設定inputType

ex:

<EditText android:layout_width="match_parent"
android:layout_height="40dp"
android:inputType="textEmailAddress"
android:layout_marginTop="10dp"
android:textColor="#000000"/>

輸入數字和小數點: numberDecimal

只能輸入數字:

android:inputType="phone"
android:digits="1234567890"

設定顏色(color)和顏色的透明度

在XML裡設定
ex:
<EditText android:layout_width="match_parent"
android:layout_height="40dp"
android:inputType="textEmailAddress"
android:layout_marginTop="10dp"
android:textColor="#000000"/>

如果有4個byte，第一個byte設定透明度
ex:
#00000000

從Java設定

ex:

seperatorView.setBackgroundColor(Color.argb(51, 255, 255, 255));
wordTextView2.setTextColor(Color.rgb(0,0,0));

ex:
calorieView.getBackground().setAlpha(127);

讓模擬器顯示虛擬鍵盤 (keyboard)

1. 點選Edit button

2. uncheck "Hardware keyboard present"

margin and padding

margin: 外部間距，和其它UI元件的間距

padding: 內部間距，UI元件自己內部的間距

ex:

android:paddingBottom="20dp"

ex:

layoutParams.setMargins(0, normalCalorieTextViewStartY, 0, 0);

2013年8月20日星期二

action bar overlay

設定action bar overlay ( themes.xml)

<resources>

<style name="FitMiTheme" parent="@android:style/Theme.Holo">
<item name="android:windowActionBarOverlay">true</item>
</style>

設定UI在action bar之後

從XML

<LinearLayout android:layout_width="match_parent"
android:layout_height="wrap_content"
android:orientation="horizontal"
android:paddingTop="?android:attr/actionBarSize" >

從Java

TypedValue tv = new TypedValue();
this.getTheme().resolveAttribute(android.R.attr.actionBarSize, tv, true);
int actionBarHeight = getResources().getDimensionPixelSize(tv.resourceId);
layoutParams.setMargins(0, actionBarHeight, 0, 0);

layout

for layout_height & layout_width:
match_parent & wrap_content

relative layout:

http://developer.android.com/reference/android/widget/RelativeLayout.LayoutParams.html

it also allows you to create overlapping views and views that appear to float on top of others.

ex:

android:layout_centerHorizontal="true"

android:layout_toRightOf="@+id/addPeriodStartDateTitleImageView"

linear layout :
延著水平或垂直排列

android:orientation="horizontal"
或
android:orientation="vertical"

ex:

<LinearLayout android:layout_width="match_parent"
android:layout_height="wrap_content"
android:orientation="horizontal" >

<Button android:text="add"
android:layout_width="0px"
android:layout_height="wrap_content"
android:layout_weight="1"
/>
FrameLayout
<Button android:text="subtract"
android:layout_width="0px"
android:layout_height="wrap_content"
android:layout_weight="1"
/>

</LinearLayout>
說明:
一樣的weight，兩個button平分畫面。記得width的寬度要設成0px。

FrameLayout

http://www.onlymobilepro.com/2012/05/22/android-frame-layout-for-absolute-beginner/

一層一層疊view。

java:

layoutParams.addRule(RelativeLayout.BELOW, titleTextView.getId());

RelativeLayout.LayoutParams layoutParams = new RelativeLayout.LayoutParams(
LayoutParams.MATCH_PARENT, LayoutParams.MATCH_PARENT);

設定背景圖片或背景顏色

每個UI元件都有background attribute

設定activity的xml:

<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:tools="http://schemas.android.com/tools"
android:layout_width="match_parent"
android:layout_height="match_parent"
android:background="@drawable/mainbackground"
tools:context=".MainActivity" >

<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:tools="http://schemas.android.com/tools"
android:layout_width="match_parent"
android:layout_height="match_parent"
android:background="#000000"
tools:context=".MainActivity" >

theme and style

http://mobile.tutsplus.com/tutorials/android/android-sdk-exploring-styles-and-themes/

1. create values/themes.xml
ex:

<?xml version="1.0" encoding="utf-8"?>
<resources>

<style name="TestTheme" parent="android:Theme.Light">
</style>

</resources>

2. modify AndroidManifest.xml

ex:

<application
android:allowBackup="true"
android:icon="@drawable/ic_launcher"
android:label="@string/app_name"
android:theme="@style/TestTheme" >

2013年8月19日星期一

App Icon image & Icon title

AndroidManifest.xml

<?xml version="1.0" encoding="utf-8"?>
<manifest xmlns:android="http://schemas.android.com/apk/res/android"
package="com.cookbook.simple_activity"
android:versionCode="1"
android:versionName="1.0">
<application android:icon="@drawable/icon"
android:label="@string/app_name">
<activity android:name=".SimpleActivity"
android:label="@string/app_name">

app version

AndroidManifest.xml

<manifest xmlns:android="http://schemas.android.com/apk/res/android"
package="com.cookbook.simple_activity"
android:versionCode="1"
android:versionName="1.0">

2013年8月18日星期日

取得硬體資訊

android.os.Build.MODEL

ex:
if(android.os.Build.MODEL.equals("Nexus+One")) { ... }

android documentation

http://developer.android.com/index.html

android version

android version比例圖表

http://developer.android.com/about/dashboards/index.html

AndroidManifest.xml:
設定minimum required SDK version and the target SDK version
ex:

<uses-sdk
android:minSdkVersion="8"
android:targetSdkVersion="17" />

說明:

minSdkVersion: API >= 8 的皆可安裝

Target SDK version: 一般採用最新的SDK

Build SDK version: 一般採用最新的SDK

設定Build SDK Version

檢查device的version

ex:

if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.HONEYCOMB) {

}

API version

http://developer.android.com/guide/topics/manifest/uses-sdk-element.html#ApiLevels

設定起始畫面activity( launcher activity )

在AndroidManifest.xml:

ex:

<application
... >
<activity
android:name="com.bignerdranch.android.geoquiz.QuizActivity"
android:label="@string/app_name" >
<intent-filter>
<action android:name="android.intent.action.MAIN" />
<category android:name="android.intent.category.LAUNCHER" />
</intent-filter>
</activity>
<activity
android:name=".CheatActivity"
android:label="@string/app_name" />
</application>

啟動舊專案

2013年8月16日星期五

activity的啟動和返回和intent

intent:
Your app should handle reasonable Intents, which is the class Android uses to indicate what the user is trying to do and to find an appropriate app to accomplish that objective
說明:
android會依據intent尋找相關的App來給使用者挑選

利用intent

public void startActivity(Intent intent);

ex:

Intent i = new Intent(QuizActivity.this, CheatActivity.class);
startActivity(i);

說明:
顯示另一個activity，原本activity的onStop被呼叫.
當按下back鍵後，將回到原來的activity

在activity間傳遞資訊: 透過intent的putExtra & getIntent

ex:

Intent i = new Intent(MainActivity.this, CheatActivity.class);
boolean answerIsTrue = mAnswerKey[mCurrentIndex].isTrueQuestion();
i.putExtra(CheatActivity.EXTRA_ANSWER_IS_TRUE, answerIsTrue);
startActivity(i);
說明:傳送

mAnswerIsTrue = getIntent().getBooleanExtra(EXTRA_ANSWER_IS_TRUE, false);

說明: 取得

Getting a result back from a child activity

1.
parent activity呼叫
public void startActivityForResult(Intent intent, int requestCode);
說明 :
之後才能夠取得child activity回傳的資料

2.
child activity呼叫
public final void setResult(int resultCode, Intent data);
說明:
回傳結果和Intent，資料包在intent裡。結果有2種:
Activity.RESULT_OK
Activity.RESULT_CANCELED.
這裡的intent有兩種產生方法:
1. Intent data = new Intent();
2. Intent i = getIntent();
get the intent that start this activity

3. parent activity經由onActivityResult取得資料
ex:

protected void onActivityResult(int requestCode, int resultCode, Intent data) {
if (data == null) {
return;
}
mIsCheater = data.getBooleanExtra(CheatActivity.EXTRA_ANSWER_SHOWN, false);
}
說明:
利用requestCode判斷是從哪個activity回來

返回:
按下back鍵或是activity物件呼叫finish method

Explicit intents:
explicitly defines the component which should be called by the Android system, by using the Java class as identifier.
ex:
Intent i = new Intent(this, ActivityTwo.class);

Implicit Intents:
Implicit intents specify the action which should be performed and optionally data which provides data for the action.

ex:

Intent i = new Intent(Intent.ACTION_VIEW, Uri.parse("http://www.vogella.com"));
startActivity(i);

說明:
The most commonly used intent filter is an action,

static analyzer : lint

設定exception breakpoint

2013年8月15日星期四

殺死執行中的App

1. 從DDMS選擇執行中的Process

2. 點選Stop button

列印stack

Log.d("MyClass", "Test", new Exception());

利用new Exception()列印stack trace

DDMS

1. 顯示Devices清單和LogCat

2. 控制LogCat顯示哪個device的log

3. 查詢device裡儲存的資料

4. 可以將檔案從device抓出或是將檔案傳到device

File Explorer

show DDMS Perspective

儲存activity的資料

protected void onSaveInstanceState(Bundle outState);

onSaveInstanceState is called before onPause(), onStop(), and onDestroy()

將資料存到bundle，之後再從bundle讀取

ex:

@Override
public void onSaveInstanceState(Bundle savedInstanceState) {
super.onSaveInstanceState(savedInstanceState);
savedInstanceState.putInt("currentIndex", mCurrentIndex);
}

說明: 儲存

@Override

protected void onCreate(Bundle savedInstanceState) {

super.onCreate(savedInstanceState);

if (savedInstanceState != null) {

mCurrentIndex = savedInstanceState.getInt(KEY_INDEX, 0);

}

說明: 讀取, 也可以override onRestoreInstanceState method讀取儲存的資料。

當使用者從App主畫面按下back鍵，存到bundle的資料將被清空

畫面的轉向(rotate)

設定不同方向時，採用不用的activity layout

landscape時將讀取layout-land資料夾

rotate emulator:
Mac: ctrl + fn + f12

限制轉向
設定AndroidManifest.xml 裡的activity
ex:

<activity
android:name=".FoodDetailActivity"
android:label="@string/app_name"
android:screenOrientation="portrait" >

</activity>

activity life cycle

App用到的activity 必須要記錄在AndroidManifest.xml

ex:

<?xml version="1.0" encoding="utf-8"?>

<manifest xmlns:android="http://schemas.android.com/apk/res/android"

package="com.example.hana"

android:versionCode="1"

android:versionName="1.0" >

<uses-sdk

android:minSdkVersion="8"

android:targetSdkVersion="17" />

<application

android:allowBackup="true"

android:icon="@drawable/ic_launcher"

android:label="@string/app_name"

android:theme="@style/AppTheme" >

<activity

android:name="com.example.hanana.MainActivity"

android:label="@string/app_name" >

<intent-filter>

</intent-filter>

</activity>

<activity

android:name=".CheatActivity"

android:label="@string/app_name" />

</application>

</manifest>

說明:
指定android:name時，開頭的package name可以用一點簡寫，如果package name等於manifest的package name。

於App的主畫面按下back鍵: 結束App， activity的onDestroy被呼叫

按下home鍵: App進入背景，onStop被呼叫

activity被destroy的case:

1. 當runtime configuration改變時，比方畫面轉向時，原本的activity會被destroy，產生新的activity。

2. 當系統需要更多的記憶體，而activity在paused or stopped狀態

Changing the screen orientation destroys and re-creates the activity from scratch.

Pressing the Home key pauses the activity but does not destroy it.

Pressing the application icon might start a new instance of the activity, even if the old one was not destroyed.

Letting the screen sleep pauses the activity, and the screen awakening resumes it. (This is similar to taking an incoming phone call.)

圖片處理

drawable-ldpi : 120 dpi
drawable-mdpi : 160 dpi
drawable-hdpi : 240 dpi
drawable-xhdpi : 320 dpi

drawable-xxhdpi : 480 dpi

加入圖片到資料夾下後，將自動產生圖片的resource ID

從XML設定圖片

ex:

<Button
android:id="@+id/next_button"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:text="@string/next_button"
android:drawableRight="@drawable/arrow_right"
android:drawablePadding="4dp" />

To adjust for the different device screen densities, we need to follow a 3:4:6:8 scaling ratio between the four density sizes. (For the iPhone, it’s easy: it’s just a 2:1 ratio between the iPhone 4 and 3GS.) Using our ratios and some simple math, we can create four different versions of our bitmap to hand off to our developer for production:
75 × 75 for low-density screens (i.e. ×0.75);
100 × 100 for medium-density screens (our baseline);
150 × 150 for high-density screens (×1.5);
200 × 200 for extra high-density screens (×2.0). (We’re concerned with only lDPI, mDPI and hDPI for Android smartphone apps.)

reference:

http://mobile.smashingmagazine.com/2011/06/30/designing-for-android/

http://developer.android.com/design/style/iconography.html

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2013年8月29日 星期四

2013年8月28日 星期三

2013年8月27日 星期二

2013年8月26日 星期一

2013年8月25日 星期日

2013年8月23日 星期五

2013年8月22日 星期四

2013年8月20日 星期二

2013年8月19日 星期一

2013年8月18日 星期日

2013年8月16日 星期五

2013年8月15日 星期四