[英]Auto change focus between two buttons periodically
package com.example.helloandroid;
import java.util.Timer;
import java.util.TimerTask;
import android.app.Activity;
import android.os.Bundle;
import android.os.Handler;
import android.util.Log;
import android.view.View;
import android.widget.Button;
public class HelloandroidActivity extends Activity {
/** Called when the activity is first created. */
Button mybtn0,mybtn1;
private Handler mhandler= new Handler();
Timer timer= new Timer();
String s=new String(" ");
int delay=0;
int period=5000;
int var=0;
@Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
// Object o=null;
// o.toString();
// TextView tv = new TextView(this);
// tv.setText("Hello Andriod");
setContentView(R.layout.main);
mybtn0= (Button)findViewById(R.id.number_button);
//mybtn.requestFocus();
mybtn0.setOnClickListener(new View.OnClickListener() {
public void onClick(View v) {
// Perform action on click
mybtn0.clearFocus();
}
});
// mybtn2= (Button)findViewById(R.id.contact_button);
//setUpFocus();
try
{
mybtn1=(Button)findViewById(R.id.contact_button);
//mybtn2= (Button)mybtn.focusSearch(View.FOCUS_DOWN);
mybtn1.requestFocus();
mybtn0.clearFocus();
}
catch(Exception e)
{
Log.e("focus change","focus failed",e);
}
timer.scheduleAtFixedRate(new TimerTask(){
public void run()
{
switch(var)
{
case 0: mybtn0.clearFocus();
mybtn1.requestFocus();
break;
case 1: mybtn1.clearFocus();
mybtn0.requestFocus();
break;
default: break;
}
var= (var+1)%2;
}
}, delay, period);
}
我已經使用上面的代碼使用計時器來完成兩個按鈕之間的自動更改焦點。 但是我收到“從錯誤的線程異常調用”。 我認為是因為計時器。 請有人更正此代碼,並提供有關如何通過Handler類實現此示例代碼。
更改計時器.schedule()看起來像這樣
timer.scheduleAtFixedRate(new TimerTask(){
public void run()
{
mHandler.sendEmptyMessage(var); // <--- I suggest you camelCase your variable names so "mhandler" should be "mHandler", it will make them easier to read at a glance.
var= (var+1)%2;
}
}, delay, period);
然后將此處理程序實例添加到您的onCreate()方法中,其中:
mHandler = new Handler() {
public void handleMessage(Message msg) {
if(msg.what == 0){
mybtn0.clearFocus();
mybtn1.requestFocus();
}else if(msg.what == 1){
mybtn1.clearFocus();
mybtn0.requestFocus();
}
}
}
您也可以一起跳過TimerTask,並隨同Handler一起進行調度。 查看.sendEmptyMessageDelayed()方法
該代碼需要在UI線程上執行。 有Activity.runOnUiThread
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