android - 如何在计时器内显示吐司？

Question

我想在计时器内显示 toast 消息，我使用了以下代码：

timer.scheduleAtFixedRate( new TimerTask()
{       
public void run()
{
    try {  
        fun1();
        } catch (Exception e) {e.printStackTrace(); }            
    }   
}, 0,60000);    

public void fun1()
{
    //want to display toast
}

我收到以下错误：

WARN/System.err(593): java.lang.RuntimeException: Can't create handler inside thread that has not called Looper.prepare()

WARN/System.err(593)：在 android.os.Handler.(Handler.java:121)

WARN/System.err(593)：在 android.widget.Toast.(Toast.java:68)

WARN/System.err(593): 在 android.widget.Toast.makeText(Toast.java:231)

谢谢。

score 7 · Accepted Answer

您不能在单独的线程中进行 UI 更新，例如 Timer。您应该使用 Handler 对象进行 UI 更新：

timer.scheduleAtFixedRate( new TimerTask() {
private Handler updateUI = new Handler(){
@Override
public void dispatchMessage(Message msg) {
    super.dispatchMessage(msg);
    fun1();
}
};
public void run() { 
try {
updateUI.sendEmptyMessage(0);
} catch (Exception e) {e.printStackTrace(); }
}
}, 0,60000);

score 2 · Accepted Answer

最简单的方法（IMO）是：

new Timer().scheduleAtFixedRate(new TimerTask() {
    @Override
    public void run() {
        final String message = "Hi";
        MyActivity.this.runOnUiThread(new Runnable() {
            @Override
            public void run() {
                Toast.makeText(MyActivity.this, message, Toast.LENGTH_SHORT).show();
            }
        });
    }
});

关键是 MyActivity.this.runOnUiThread(Runnable)。

score 0 · Accepted Answer

您必须调用 UIThread 来显示 Toast，而不是来自计时器线程。

否则从该计时器线程调用 UI 线程。

这个链接会帮助你，

http://developer.android.com/resources/articles/timed-ui-updates.html

还有这个

http://developer.android.com/guide/appendix/faq/commontasks.html#threading

score 0 · Accepted Answer

在此创建Handler并显示吐司

private Handler handler = new Handler() {
        public void handleMessage(android.os.Message msg) {
            // Toast here
        }
    };

score 0 · Accepted Answer

您需要访问应用程序的上下文才能执行此操作。尝试创建您自己的类，该类将上下文作为输入参数：

private class MyTimerTask extends TimerTask {
    private Context context;
    public MyTimerTask(Context context) {
        this.context = context;
    }

    @Override
    public void run() {
        Toast.makeText(context, "Toast text", Toast.LENGTH_SHORT).show();
    }

}

然后在你的计时器中：

timer.scheduleAtFixedRate( new MyTimerTask(this), 0,60000);

score 0 · Accepted Answer

我试图用我自己的观点做我自己的祝酒词。

我已经成功地结合了你的方法。下面的代码允许我在不崩溃的情况下显示 toast 和更改/删除视图，只需将MyTimerTask构造函数的参数更改为您需要处理的任何内容。

public void yourFunction(){

    Timer timer = new Timer();
    MyTimerTask mtc = new MyTimerTask(this.getContext(), tvNotice);
    timer.schedule(mtc, 1000);
}

private class MyTimerTask extends TimerTask {

    private TextView tv;
    private Context context;
    public MyTimerTask(Context pContext, TextView pTv) {
        this.tv = pTv;
        this.context = pContext;
    }
    @Override
    public void run() {
        updateUI.sendEmptyMessage(0);
    }

    private Handler updateUI = new Handler(){
        @Override
        public void dispatchMessage(Message msg) {
            super.dispatchMessage(msg);


            tv.setText("TextView Message");
            Toast.makeText(context, "Toast Message", 0).show();
        }
    };
}

score 0 · Accepted Answer

我想做一个简单的项目，可以在计时器中显示 Toast。计时器将使用服务启动。然后，定时器在服务启动时启动，在服务停止时停止。

1级

package com.example.connect;


import android.app.Activity;
import android.content.Intent;
import android.os.Bundle;
import android.os.Handler;
import android.view.View;
import android.widget.Button;

public class MainActivity extends Activity {

Button button1,button2;
 private Handler mHandler = new Handler();

@Override
public void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.activity_main);

    button1=(Button)findViewById(R.id.button1);
    button2=(Button)findViewById(R.id.button2);


}


public void Start(View v)
{
    startService(new Intent(MainActivity.this , Connect_service.class));

}

public void Stop(View v)
{
    stopService(new Intent(MainActivity.this , Connect_service.class));

}

}

2 级

package com.example.connect;

import java.util.Timer;
import java.util.TimerTask;

import android.app.Service;
import android.content.Intent;
import android.os.IBinder;
import android.widget.Toast;

public class Connect_service extends Service{

Timer timer = new Timer();
TimerTask updateProfile = new CustomTimerTask(Connect_service.this);

public void onCreate() {

    super.onCreate();

    Toast.makeText(this, "Service Started", Toast.LENGTH_SHORT).show();
    timer.scheduleAtFixedRate(updateProfile, 0, 5000);

}


@Override
public void onDestroy() {
    // TODO Auto-generated method stub
    super.onDestroy();
    Toast.makeText(this, "Service Stopped", Toast.LENGTH_SHORT).show();
    timer.cancel();
}



@Override
public IBinder onBind(Intent intent) {
    // TODO Auto-generated method stub
    return null;
}

}

3 级

package com.example.connect;

import java.util.TimerTask;

import android.content.Context;
import android.os.Handler;
import android.widget.Toast;
public class CustomTimerTask extends TimerTask {


private Context context;
private Handler mHandler = new Handler();

public CustomTimerTask(Context con) {
    this.context = con;
}



@Override
public void run() {
    new Thread(new Runnable() {

        public void run() {

            mHandler.post(new Runnable() {
                public void run() {
                   Toast.makeText(context, "In Timer", Toast.LENGTH_SHORT).show();

                }
            });
        }
    }).start();

}

}

android - 如何在计时器内显示吐司？

7 回答 7

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