Android考虑到线程安全问题,不允许在线程中执行UI线程。
所以在线程中不允许有UI操作
可以利用Handler机制来接收Timer每隔一秒发出的信息,也可以直接利用handler机制的
1、方法一:Handler+Thread
package com.example.yuyin_lixian; import android.os.Bundle; import android.app.Activity; import android.view.Menu; import java.util.Timer; import java.util.TimerTask; import android.app.Activity; import android.os.Bundle; import android.os.Handler; import android.os.Message; import android.util.Log; import android.view.View; import android.widget.Button; import android.widget.TextView; /** * handler定时器 * * @author Smalt * */ public class MainActivity extends Activity { TextView tvShow; private int i = 0; @Override public void onCreate(Bundle savedInstanceState) { super.onCreate(savedInstanceState); setContentView(R.layout.activity_main); tvShow = (TextView) findViewById(R.id.textView1); new Thread(new ThreadShow()).start(); } // handler类接收数据 Handler handler = new Handler() { public void handleMessage(Message msg) { if (msg.what == 1) { tvShow.setText(Integer.toString(i++)); System.out.println("receive...."); } }; }; // 线程类 class ThreadShow implements Runnable { @Override public void run() { // TODO Auto-generated method stub while (true) { try { Thread.sleep(1000); //每隔一秒执行一次 Message msg = new Message(); msg.what = 1; handler.sendMessage(msg); System.out.println("send..."); } catch (Exception e) { // TODO Auto-generated catch block e.printStackTrace(); System.out.println("thread error..."); } } } } }
2、方法二:Handler类自带的postDelyed
其中使用PostDelayed方法,1秒后调用此Runnable对象
handler.postDelayed(runnable, 1000); 实际上也就实现了一个1s的一个定时器
如果想要关闭此定时器,可以这样操作
handler.removeCallbacks(runnable);
package com.example.yuyin_lixian; import android.app.Activity; import android.os.Bundle; import android.os.Handler; import android.widget.TextView; /** * handler定时器使用postDelyed实现 * * @author Smalt * */ public class MainActivity extends Activity { TextView tvShow; private int i = 0; private int TIME = 1000; @Override public void onCreate(Bundle savedInstanceState) { super.onCreate(savedInstanceState); setContentView(R.layout.activity_main); tvShow = (TextView) findViewById(R.id.textView1); handler.postDelayed(runnable, TIME); //每隔1s执行 } Handler handler = new Handler(); Runnable runnable = new Runnable() { @Override public void run() { // handler自带方法实现定时器 try { handler.postDelayed(this, TIME); tvShow.setText(Integer.toString(i++)); System.out.println("do..."); } catch (Exception e) { // TODO Auto-generated catch block e.printStackTrace(); System.out.println("exception..."); } } }; }
3、方法二:Handler+Timer+TimerTask
package com.example.yuyin_lixian; import java.util.Timer; import java.util.TimerTask; import android.app.Activity; import android.os.Bundle; import android.os.Handler; import android.os.Message; import android.widget.TextView; /** * 定时器实现:Handler+Timer+TimerTask * * @author Smalt * */ public class MainActivity extends Activity { TextView tvShow; private int i = 0; private int TIME = 1000; @Override public void onCreate(Bundle savedInstanceState) { super.onCreate(savedInstanceState); setContentView(R.layout.activity_main); tvShow = (TextView) findViewById(R.id.textView1); timer.schedule(task, 1000, 1000); // 1s后执行task,经过1s再次执行 } Handler handler = new Handler() { public void handleMessage(Message msg) { if (msg.what == 1) { tvShow.setText(Integer.toString(i++)); } super.handleMessage(msg); }; }; Timer timer = new Timer(); TimerTask task = new TimerTask() { @Override public void run() { // 需要做的事:发送消息 Message message = new Message(); message.what = 1; handler.sendMessage(message); } }; }