Android 更新UI的幾種方式，android更新ui幾種

Android 更新UI的幾種方式，android更新ui幾種
1、Activity的 runOnUiThread   

 textView = (TextView) findViewById( R.id.tv );        new Thread(new Runnable() {            @Override            public void run() {                runOnUiThread(new Runnable() {                    @Override                    public void run() {                        textView.setText( "更新UI了");                    }                });            }        }).start();

android Activity runOnUiThread() 方法使用2、Handler sendEmptyMessage()

package lib.com.myapplication;import android.os.Handler;import android.os.Message;import android.support.v7.app.AppCompatActivity;import android.os.Bundle;import android.widget.TextView;public class MainActivity extends AppCompatActivity {    private TextView textView ;    Handler handler = new Handler( ) {        @Override        public void handleMessage(Message msg) {            super.handleMessage(msg);            textView.setText( "Ui更新了");        }    };    @Override    protected void onCreate(Bundle savedInstanceState) {        super.onCreate(savedInstanceState);        setContentView(R.layout.activity_main);        textView = (TextView) findViewById( R.id.tv );        new Thread(new Runnable() {            @Override            public void run() {                try {                    Thread.sleep( 2000 );                } catch (InterruptedException e) {                    e.printStackTrace();                }                handler.sendEmptyMessage( 2 ) ;            }        }).start();    }}

3、Handler  post()

package lib.com.myapplication;import android.os.Bundle;import android.os.Handler;import android.support.v7.app.AppCompatActivity;import android.widget.TextView;public class MainActivity extends AppCompatActivity {    private TextView textView ;    Handler handler = new Handler();    @Override    protected void onCreate(Bundle savedInstanceState) {        super.onCreate(savedInstanceState);        setContentView(R.layout.activity_main);        textView = (TextView) findViewById( R.id.tv );        new Thread(new Runnable() {            @Override            public void run() {                try {                    Thread.sleep( 2000 );                } catch (InterruptedException e) {                    e.printStackTrace();                }                handler.post(new Runnable() {                    @Override                    public void run() {                        textView.setText( "Ui更新了");                    }                }) ;            }        }).start();    }}

4、view Post()　

 textView = (TextView) findViewById( R.id.tv );        new Thread(new Runnable() {            @Override            public void run() {                try {                    Thread.sleep( 2000 );                } catch (InterruptedException e) {                    e.printStackTrace();                }                textView.post(new Runnable() {                    @Override                    public void run() {                        textView.setText( "Ui更新了");                    }                }) ;            }        }).start();

總結：

1、其實上面的四種方式都可歸結於一種方式：handler 用於Android線程之間的通訊。

2、為什麼android要求只能在UI線程進行UI操作？ 主要還是為了避免多線程造成的並發的問題。在單線程操作UI是安全的。