EditText自定义监听方法实现onFocusChanged的监听

<div class="line number1 index0 alt2" style="list-style: none; line-height: 15.4px; font-family: Consolas, 'Bitstream Vera Sans Mono', 'Courier New', Courier, monospace; font-size: 14px; box-sizing: content-box !important; margin: 0px !important; padding: 0px 1em !important; border: 0px !important; outline: 0px !important; border-radius: 0px !important; bottom: auto !important; float: none !important; height: auto !important; left: auto !important; overflow: visible !important; position: static !important; right: auto !important; top: auto !important; vertical-align: baseline !important; width: auto !important; min-height: auto !important; background-image: none !important; background-attachment: initial !important; background-size: initial !important; background-origin: initial !important; background-clip: initial !important; background-position: initial !important; background-repeat: initial !important;"><span style="color: rgb(0, 102, 153);"><span style="white-space: nowrap;"><span style="font-weight: bold;"><span style="line-height: 15.4px;">    有一定开发经验的程序员知道，EditText控件位于一个Activity的布局最上方时，当<span style="line-height: 15.4px;"><span style="line-height: 15.4px;">EditText实现onFocusChanged的监听方法时，</span></span></span></span></span></span></div><div class="line number1 index0 alt2" style="list-style: none; line-height: 15.4px; font-family: Consolas, 'Bitstream Vera Sans Mono', 'Courier New', Courier, monospace; font-size: 14px; box-sizing: content-box !important; margin: 0px !important; padding: 0px 1em !important; border: 0px !important; outline: 0px !important; border-radius: 0px !important; bottom: auto !important; float: none !important; height: auto !important; left: auto !important; overflow: visible !important; position: static !important; right: auto !important; top: auto !important; vertical-align: baseline !important; width: auto !important; min-height: auto !important; background-image: none !important; background-attachment: initial !important; background-size: initial !important; background-origin: initial !important; background-clip: initial !important; background-position: initial !important; background-repeat: initial !important;"><span style="color: rgb(0, 102, 153);"><span style="white-space: nowrap;"><span style="font-weight: bold;"><span style="line-height: 15.4px;"><span style="line-height: 15.4px;"><span style="line-height: 15.4px;">程序运行的时候，输入光标会自动定位到EditText控件中，这时会触发<span style="line-height: 15.4px;"><span style="line-height: 15.4px;"><span style="line-height: 15.4px;"><span style="line-height: 15.4px;">onFocusChanged监听，执行里面的方法。这会导致一些麻烦</span></span></span></span></span></span></span></span></span></span></div><div class="line number1 index0 alt2" style="list-style: none; line-height: 15.4px; font-family: Consolas, 'Bitstream Vera Sans Mono', 'Courier New', Courier, monospace; font-size: 14px; box-sizing: content-box !important; margin: 0px !important; padding: 0px 1em !important; border: 0px !important; outline: 0px !important; border-radius: 0px !important; bottom: auto !important; float: none !important; height: auto !important; left: auto !important; overflow: visible !important; position: static !important; right: auto !important; top: auto !important; vertical-align: baseline !important; width: auto !important; min-height: auto !important; background-image: none !important; background-attachment: initial !important; background-size: initial !important; background-origin: initial !important; background-clip: initial !important; background-position: initial !important; background-repeat: initial !important;"><span style="color: rgb(0, 102, 153);"><span style="white-space: nowrap;"><strong>（例如空指针）。针对这种情况该怎样解决呢？下面的一个例子利用继承和接口回调实现了onFocusChanged监听方法。</strong></span></span></div><div class="line number1 index0 alt2" style="list-style: none; line-height: 15.4px; font-family: Consolas, 'Bitstream Vera Sans Mono', 'Courier New', Courier, monospace; font-size: 14px; box-sizing: content-box !important; margin: 0px !important; padding: 0px 1em !important; border: 0px !important; outline: 0px !important; border-radius: 0px !important; bottom: auto !important; float: none !important; height: auto !important; left: auto !important; overflow: visible !important; position: static !important; right: auto !important; top: auto !important; vertical-align: baseline !important; width: auto !important; min-height: auto !important; background-image: none !important; background-attachment: initial !important; background-size: initial !important; background-origin: initial !important; background-clip: initial !important; background-position: initial !important; background-repeat: initial !important;"><span style="color: rgb(0, 102, 153);"><span style="white-space: nowrap;"><strong> 具体步骤如下：</strong></span></span></div><div class="line number1 index0 alt2" style="list-style: none; line-height: 15.4px; font-family: Consolas, 'Bitstream Vera Sans Mono', 'Courier New', Courier, monospace; font-size: 14px; box-sizing: content-box !important; margin: 0px !important; padding: 0px 1em !important; border: 0px !important; outline: 0px !important; border-radius: 0px !important; bottom: auto !important; float: none !important; height: auto !important; left: auto !important; overflow: visible !important; position: static !important; right: auto !important; top: auto !important; vertical-align: baseline !important; width: auto !important; min-height: auto !important; background-image: none !important; background-attachment: initial !important; background-size: initial !important; background-origin: initial !important; background-clip: initial !important; background-position: initial !important; background-repeat: initial !important;"><span style="color: rgb(0, 102, 153);"><span style="white-space: nowrap;"><strong>     一、写一个MyEditText类继承EditText,定义一个内部类接口<span style="line-height: 15.4px;">OnImputCompleteListener，该接口具有<code class="java keyword" style="list-style: none; font-size: 1em !important; line-height: 1.1em !important; box-sizing: content-box !important; font-family: Consolas, 'Bitstream Vera Sans Mono', 'Courier New', Courier, monospace !important; padding: 0px !important; border-radius: 0px !important; margin: 0px !important; border: 0px !important; outline: 0px !important; bottom: auto !important; float: none !important; height: auto !important; left: auto !important; overflow: visible !important; position: static !important; right: auto !important; top: auto !important; vertical-align: baseline !important; width: auto !important; min-height: auto !important; background: none !important;">void</code><span style="color: rgb(51, 51, 51); line-height: 15.4px; white-space: pre;"> </span><code class="java plain" style="list-style: none; font-size: 1em !important; line-height: 1.1em !important; box-sizing: content-box !important; font-family: Consolas, 'Bitstream Vera Sans Mono', 'Courier New', Courier, monospace !important; padding: 0px !important; border-radius: 0px !important; margin: 0px !important; border: 0px !important; outline: 0px !important; bottom: auto !important; float: none !important; height: auto !important; left: auto !important; overflow: visible !important; position: static !important; right: auto !important; top: auto !important; vertical-align: baseline !important; width: auto !important; min-height: auto !important; background: none !important;">onImputComplete()</code></span></strong></span></span></div><div class="line number1 index0 alt2" style="list-style: none; line-height: 15.4px; font-family: Consolas, 'Bitstream Vera Sans Mono', 'Courier New', Courier, monospace; font-size: 14px; box-sizing: content-box !important; margin: 0px !important; padding: 0px 1em !important; border: 0px !important; outline: 0px !important; border-radius: 0px !important; bottom: auto !important; float: none !important; height: auto !important; left: auto !important; overflow: visible !important; position: static !important; right: auto !important; top: auto !important; vertical-align: baseline !important; width: auto !important; min-height: auto !important; background-image: none !important; background-attachment: initial !important; background-size: initial !important; background-origin: initial !important; background-clip: initial !important; background-position: initial !important; background-repeat: initial !important;"><span style="color: rgb(0, 102, 153);"><span style="white-space: nowrap;"><strong>方法.</strong></span></span></div><div class="line number1 index0 alt2" style="list-style: none; line-height: 15.4px; font-family: Consolas, 'Bitstream Vera Sans Mono', 'Courier New', Courier, monospace; font-size: 14px; box-sizing: content-box !important; margin: 0px !important; padding: 0px 1em !important; border: 0px !important; outline: 0px !important; border-radius: 0px !important; bottom: auto !important; float: none !important; height: auto !important; left: auto !important; overflow: visible !important; position: static !important; right: auto !important; top: auto !important; vertical-align: baseline !important; width: auto !important; min-height: auto !important; background-image: none !important; background-attachment: initial !important; background-size: initial !important; background-origin: initial !important; background-clip: initial !important; background-position: initial !important; background-repeat: initial !important;"><span style="color: rgb(0, 102, 153);"><span style="white-space: nowrap;"><strong>    二 、在MyEditText中添加<code class="java keyword" style="list-style: none; font-size: 1em !important; line-height: 1.1em !important; box-sizing: content-box !important; font-family: Consolas, 'Bitstream Vera Sans Mono', 'Courier New', Courier, monospace !important; padding: 0px !important; border-radius: 0px !important; margin: 0px !important; border: 0px !important; outline: 0px !important; bottom: auto !important; float: none !important; height: auto !important; left: auto !important; overflow: visible !important; position: static !important; right: auto !important; top: auto !important; vertical-align: baseline !important; width: auto !important; min-height: auto !important; background: none !important;">private</code><span style="color: rgb(51, 51, 51); line-height: 15.4px; white-space: pre;"> </span><code class="java plain" style="list-style: none; font-size: 1em !important; line-height: 1.1em !important; box-sizing: content-box !important; font-family: Consolas, 'Bitstream Vera Sans Mono', 'Courier New', Courier, monospace !important; padding: 0px !important; border-radius: 0px !important; margin: 0px !important; border: 0px !important; outline: 0px !important; bottom: auto !important; float: none !important; height: auto !important; left: auto !important; overflow: visible !important; position: static !important; right: auto !important; top: auto !important; vertical-align: baseline !important; width: auto !important; min-height: auto !important; background: none !important;">OnImputCompleteListener mOnImputCompleteListener属性；</code></strong></span></span></div><div class="line number1 index0 alt2" style="list-style: none; line-height: 15.4px; font-family: Consolas, 'Bitstream Vera Sans Mono', 'Courier New', Courier, monospace; font-size: 14px; box-sizing: content-box !important; margin: 0px !important; padding: 0px 1em !important; border: 0px !important; outline: 0px !important; border-radius: 0px !important; bottom: auto !important; float: none !important; height: auto !important; left: auto !important; overflow: visible !important; position: static !important; right: auto !important; top: auto !important; vertical-align: baseline !important; width: auto !important; min-height: auto !important; background-image: none !important; background-attachment: initial !important; background-size: initial !important; background-origin: initial !important; background-clip: initial !important; background-position: initial !important; background-repeat: initial !important;"><span style="white-space: nowrap; color: rgb(0, 102, 153); line-height: 15.4px;">添加<span style="line-height: 15.4px;">setOnImputCompleteListener<span style="line-height: 15.4px;">(OnImputCompleteListener </span><span style="line-height: 15.4px;">onImputCompleteListener</span><span style="line-height: 15.4px;">)</span>方法，</span></span></div><div class="line number1 index0 alt2" style="list-style: none; line-height: 15.4px; font-family: Consolas, 'Bitstream Vera Sans Mono', 'Courier New', Courier, monospace; font-size: 14px; box-sizing: content-box !important; margin: 0px !important; padding: 0px 1em !important; border: 0px !important; outline: 0px !important; border-radius: 0px !important; bottom: auto !important; float: none !important; height: auto !important; left: auto !important; overflow: visible !important; position: static !important; right: auto !important; top: auto !important; vertical-align: baseline !important; width: auto !important; min-height: auto !important; background-image: none !important; background-attachment: initial !important; background-size: initial !important; background-origin: initial !important; background-clip: initial !important; background-position: initial !important; background-repeat: initial !important;"><span style="white-space: nowrap; color: rgb(0, 102, 153); line-height: 15.4px;"><span style="line-height: 15.4px;">使MyEditText具有<span style="line-height: 15.4px;"><span style="line-height: 15.4px;">OnImputCompleteListener类的的属性，并且能够初始化。</span></span></span></span></div><div class="line number1 index0 alt2" style="list-style: none; line-height: 15.4px; font-family: Consolas, 'Bitstream Vera Sans Mono', 'Courier New', Courier, monospace; font-size: 14px; box-sizing: content-box !important; margin: 0px !important; padding: 0px 1em !important; border: 0px !important; outline: 0px !important; border-radius: 0px !important; bottom: auto !important; float: none !important; height: auto !important; left: auto !important; overflow: visible !important; position: static !important; right: auto !important; top: auto !important; vertical-align: baseline !important; width: auto !important; min-height: auto !important; background-image: none !important; background-attachment: initial !important; background-size: initial !important; background-origin: initial !important; background-clip: initial !important; background-position: initial !important; background-repeat: initial !important;"><span style="white-space: nowrap; color: rgb(0, 102, 153); line-height: 15.4px;"><span style="line-height: 15.4px;"><span style="line-height: 15.4px;"><span style="line-height: 15.4px;">    三、在重写的</span></span></span><span style="line-height: 15.4px;"><span style="line-height: 15.4px;"><span style="line-height: 15.4px;">onFocusChanged中实现<span style="line-height: 15.4px;"><span style="line-height: 15.4px;"><span style="line-height: 15.4px;"><span style="line-height: 15.4px;">OnImputCompleteListener接口的<span style="line-height: 15.4px;"><span style="line-height: 15.4px;"><code class="java plain" style="list-style: none; font-size: 1em !important; line-height: 1.1em !important; box-sizing: content-box !important; font-family: Consolas, 'Bitstream Vera Sans Mono', 'Courier New', Courier, monospace !important; padding: 0px !important; border-radius: 0px !important; margin: 0px !important; border: 0px !important; outline: 0px !important; bottom: auto !important; height: auto !important; left: auto !important; overflow: visible !important; position: static !important; right: auto !important; top: auto !important; vertical-align: baseline !important; width: auto !important; min-height: auto !important; background: none !important;">onImputComplete()方法。具体代码如下：</code></span></span></span></span></span></span></span></span></span></span></div>

public class MyEditText extends EditText{         private OnImputCompleteListener mOnImputCompleteListener;     public MyEditText(Context context) {        super(context);    }     public MyEditText(Context context, AttributeSet attrs) {       super(context, attrs);    }     public MyEditText(Context context, AttributeSet attrs, int defStyleAttr) {       super(context, attrs, defStyleAttr);    }     @SuppressLint("NewApi")    public MyEditText(Context context, AttributeSet attrs, int defStyleAttr, int defStyleRes) {       super(context, attrs, defStyleAttr, defStyleRes);    }         @Override    protected void onFocusChanged(boolean focused, int direction,            Rect previouslyFocusedRect) {        super.onFocusChanged(focused, direction, previouslyFocusedRect);                 if (!focused) {            mOnImputCompleteListener.onImputComplete();        }    }         public void setOnImputCompleteListener(OnImputCompleteListener onImputCompleteListener) {        this.mOnImputCompleteListener = onImputCompleteListener;    } } interface OnImputCompleteListener {    void onImputComplete();}