stackoverflow转载(关于对attributeSet理解)

how to define AttributeSet parameter for extended layout

up vote 1 down vote favorite

I am having trouble understanding how to instantiate a custom layout in code. Specifically I do not know how to define the requiredAttributeSet parameter. I have gone through the official docs but could not wrap my head around it : http://developer.android.com/training/custom-views/create-view.htmlhttp://developer.android.com/reference/android/util/AttributeSet.html In my activity, i instantiate it with : new MyCustomLayout(getActivity(), attrs) But how do i define attrs? MyCustomLayout.java public class MyCustomLayout extends LinearLayout implements OnClickListener { ... ... public MyCustomLayout(Context context, AttributeSet attrs) { super(context, attrs); LayoutInflater inflater = (LayoutInflater) context.getSystemService(Context.LAYOUT_INFLATER_SERVICE); View view = inflater.inflate(R.layout.mycustomxmllayout, this, true); ... } ... } mycustomxmllayout.xml xml version="1.0" encoding="utf-8"?> xmlns:android="http://schemas.android.com/apk/res/android" > android:id="@+id/txt_1" android:layout_width="60dp" android:layout_height="wrap_content" android:layout_weight="2" android:lines="1"/> android:id="@+id/btn_1" android:layout_width="wrap_content" android:layout_height="wrap_content" android:minHeight="0dp" android:minWidth="0dp" android:background="@null" android:text="x" android:layout_weight="1" /> android share edit edited Nov 1 '14 at 6:50 asked Nov 1 '14 at 6:33 faizal 1,515 2 16 33

add a comment

1 Answer

active oldest votes

up vote 1 down vote accepted

Firstly, you should define your custom attributes in the res/values/attrs.xml, just add, for example: name="MyCustomLayout"> name="showText" format="boolean" /> name="buttonPosition" format="enum"> name="left" value="0"/> name="right" value="1"/> Now you can set your custom attrs via xml, like this: xmlns:android="http://schemas.android.com/apk/res/android" xmlns:custom="http://schemas.android.com/apk/res-auto"> android:layout_width="match_parent" android:layout_height="match_parent" custom:showText="true" custom:buttonPosition="left" /> And in your constructor you can grab that attrs: public MyCustomLayout(Context context, AttributeSet attrs) { super(context, attrs); TypedArray a = context.getTheme().obtainStyledAttributes( attrs, R.styleable.MyCustomLayout, 0, 0); try { mShowText = a.getBoolean(R.styleable.MyCustomLayout_showText, false); mButtonPos = a.getInteger(R.styleable.MyCustomLayout_buttonPosition, 0); } finally { a.recycle(); } } If you want to set your attrs programmatically, you should create public getters/setters for that: private boolean mShowText; private Integer mButtonPos; public void setButtonPos(int pos) { mButtonPos = pos; } public void setShowText(boolean showText) { mShowText = showText; } After that you can set your attrs programmatically: MyCustomLayout layout = new MyCustomLayout(getActivity()); layout.setButtonPos(0); layout.setShowText(true); share edit answered Nov 1 '14 at 6:58 rom4ek 3,151 2 6 14

that's interesting. I was hoping to simply reuse the existing attributes of the framework's LinearLayout. That is why i extended it. I do not want to defined any custom attributes. Do you think that is possible? –  faizal Nov 1 '14 at 7:03 What attrs do you want to use, for example? And where do you want to use it? –  rom4ek Nov 1 '14 at 7:06 I just need theAttributeSet parameter to instantiate the layout in my activity i.e. the second parameter innew MyCustomLayout(getActivity(), attrs). So whatever is the minimum required to get it working is all i am looking for. I am guessing this meanslayout_height and layout_width. If i can skip the parameter all together, it would be even better. –  faizal Nov 1 '14 at 7:10 1   The constructor that haveattrs parameter is only used when you create your layout from xml, not programmatically. If you create your layout programmatically you should also set it properties programmatically. –  rom4ek Nov 1 '14 at 7:12 So instead of usingsuper(context, attrs) in my constructor, are you saying i can simply usesuper(context) and then set the required attributes using setLayoutParams() ? –  faizal Nov 1 '14 at 7:24 事实上理解 AttributeSet就要明白:      1:how do i get attribute sets in the activity to pass to my custom Class       2:一般的: The AttributeSet Constructrs is used when a view is inflated through a layout define in XML  . if you are constructing one in code ,you should use the single argument construct     3: 但是 如果你一定使用 no-single argument constructor 那么你可以按照上面(stackOverflow)的写法来做   就是在 custom class 添加setter/getter方法