Android中的Handler机制

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public class HandlerTestActivity extends Activity {

    private TextView tv;

    private static final int UPDATE = 0;

    private Handler handler = new Handler() {

        @Override

        public void handleMessage(Message msg) {

            // TODO 接收消息并且去更新UI线程上的控件内容

            if (msg.what == UPDATE) {

                // Bundle b = msg.getData();

                // tv.setText(b.getString("num"));

                tv.setText(String.valueOf(msg.obj));

            }

            super.handleMessage(msg);

        }

    };

    /** Called when the activity is first created. */

    @Override

    public void onCreate(Bundle savedInstanceState) {

        super.onCreate(savedInstanceState);

        setContentView(R.layout.main);

        tv = (TextView) findViewById(R.id.tv);

        new Thread() {

            @Override

            public void run() {

                // TODO 子线程中通过handler发送消息给handler接收，由handler去更新TextView的值

                try {

                    for (int i = 0; i < 100; i++) {

                        Thread.sleep(500);

                        Message msg = new Message();

                        msg.what = UPDATE;

                        // Bundle b = new Bundle();

                        // b.putString("num", "更新后的值：" + i);

                        // msg.setData(b);

                        msg.obj = "更新后的值：" + i;

                        handler.sendMessage(msg);

                    }

                } catch (InterruptedException e) {

                    e.printStackTrace();

                }

            }

        }.start();

    }

}