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一：工作线程中的回掉更新UI
public class MainActivity extends AppCompatActivity { private int i; private Callback mCallback; private TextView textView; @Override protected void onCreate(Bundle savedInstanceState) { super.onCreate(savedInstanceState); setContentView(R.layout.activity_main); textView = (TextView) findViewById(R.id.text); mCallback = new Callback() { @Override public void callback(int i) { textView.setText("i"); } }; doWorkAsNewThread(5000,mCallback); } /** * 开启工作线程 * @param delayMs 延时，以便对比 * @param callback 回掉，更新Ui */ private void doWorkAsNewThread(final long delayMs, final Callback callback){ new Thread(){ @Override public void run() { super.run(); try { Thread.sleep(delayMs); } catch (InterruptedException e) { e.printStackTrace(); } do { i++; }while(i<100); callback.callback(i); } }.start(); } interface Callback{ void callback(int i); }
可以看到5s后报错了：Only the original thread that created a view hierarchy can touch its views.
二：改造2，在线程里切换到UI线程回掉
private void doWorkAsNewThread(final long delayMs, final Callback callback){ new Thread(){ @Override public void run() { super.run(); try { Thread.sleep(delayMs); } catch (InterruptedException e) { e.printStackTrace(); } do { i++; }while(i<100); textView.post(new Runnable() { @Override public void run() { callback.callback(i); } }); } }.start(); }
这样是可行的，没报错。直接在Callback中改也可以：
mCallback = new Callback() { @Override public void callback(final int i) { textView.post(new Runnable() { @Override public void run() { textView.setText(String.valueOf(i)); } }); } };
但是两边都有回掉的话，好像会有问题。
三：异步线程内，用handler去更新是无效的。
new Handler().post(new Runnable() { @Override public void run() { textView.setText(String.valueOf(i)); } });
Can‘t create handler inside thread that has not called Looper.prepare()
加上loop一样还是其他线程。
Looper.prepare(); new Handler().post(new Runnable() { @Override public void run() { textView.setText(String.valueOf(i)); } }); Looper.loop();
四：回掉自行区分选择在哪个线程：
private void callbackOnWorkThread(final int i, final Callback callback){ Looper.prepare(); new Handler().post(new Runnable() { @Override public void run() { callback.callback(i); } }); Looper.loop(); } private void callbackOnMainThread(final int i, final Callback callback){ new Handler(Looper.getMainLooper()).post(new Runnable() { @Override public void run() { callback.callback(i); } }); }
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原文地址：http://www.cnblogs.com/bvin/p/5390769.html
