Some problems with the Android Custom View construction method

<span id="Label3"></p><p><p>In Android development, you will often customize the view, then you will use construction methods, such as custom myview, inherit view, will require the implementation of the construction method:</p></p><pre><pre> <span style="color: #0000ff;"></span> public <span style="color: #000000;">MyView (context Context) { </span><span style="color: #0000ff;">Super</span><span style="color: #000000;">(context);<br>LOG.V ("MyView", "MyView (context context)"); </span> <span style="color: #0000ff;"></span> public <span style="color: #000000;">MyView (context context, attributeset attrs) { </span><span style="color: #0000ff;">Super</span><span style="color: #000000;">(context, attrs);<br>LOG.V ("MyView", "MyView (context context, attributeset attrs)"); </span> <span style="color: #0000ff;"></span> public <span style="color: #0000ff;">int</span> <span style="color: #000000;">Defstyleattr) { </span><span style="color: #0000ff;">Super</span><span style="color: #000000;">(context, attrs, defstyleattr); }</span></pre></pre><p><p>so, in the process of real use, how exactly is it called?</p></p><p><p>Add directly to the OnCreate in mainactivity</p></p><p><p>MyView MyView = new MyView (this);</p></p><p><p>The log that was played:</p></p><p><p>06-14 13:19:53.867 21160-21160/? V/myview:myview (context Context)</p></p><p><p>This means that the first constructor method is called</p></p><p><p>When we add in the layout (XML)</p></p><pre><pre><span style="color: #0000ff;"><</span> <span style="color: #800000;">Li.deng.com.test.view.MyView </span> <span style="color: #ff0000;">Android:layout_width</span> <span style="color: #0000ff;">= "match_parent"</span> <span style="color: #ff0000;"> android:layout_height</span><span style="color: #0000ff;">= "wrap_content"</span><span style="color: #0000ff;">/></span></pre></pre><p><p>Comment Out//myview MyView = new MyView (this);</p></p><p><p>Print Log:</p></p><p><p>06-14 13:25:07.196 22697-22697/? V/myview:myview (context context, AttributeSet attrs)</p></p><p><p>before, every time you look at someone Else's code is this:</p></p><pre><pre> <span style="color: #0000ff;">private </span> <span style="color: #000000;"> Context mcontext; </span> <span style="color: #0000ff;">public </span> <span style="color: #000000;"> MyView (context Context) {</span> <span style="color: #0000ff;">super </span> <span style="color: #000000;" (context); log.v (< span> "MyView", "MyView (context)" <span style="color: #000000;" "); < span> <span style="color: #0000ff;">this </span>. mcontext =<span style="color: #000000;"> context; </span> <span style="color: #0000ff;">public </span> <span style="color: #000000;"> MyView (context context, AttributeSet attrs) {</span> <span style="color: #0000ff; >super </span> <span style=" color: #000000; "> (context, att rs); LOG.V (</span> "MyView", "MyView (context context, attributeset attrs)" <span style="color: #000000;">); This.mcontext </span> =<span style="color: #000000;"> context; }</span></span></span></pre></pre><p><p>before, not particularly understand why to write so many construction methods, now understand the use of the construction method, this is because in the process of development, their own definition of</p></p><pre><pre><span>Public<span> MyView (context Context) { Super<span>(context); LOG.V ("MyView", "MyView (context context)"<span>); This.mcontext =<span> context; }<br></span></span></span></span></span>While using the process is defined in the layout file when the view, so that no context object, The result is a null pointer, and then looked at the construction method related knowledge, You must implement the second construction method</pre></pre><pre><pre><span>Public<span> MyView (context context, attributeset attrs) { Super<span>(context, attrs); LOG.V ("MyView", "MyView (context context, attributeset attrs)"<span>); This.mcontext =<span> context; }</span> </span> </span> </span></span><br><br>Reference Article: http://825288003.iteye.com/blog/1595213<br></pre></pre><pre><pre><br><br></pre></pre><p><p></p></p><p><p>Some problems with the Android Custom View construction method</p></p></span>