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分享Only one Looper may be created per thread问题
我在ui线程创建一个handler和一个子线程，再在子线程建了一个handler，在子线程的handler里面去模拟一个耗时操作，但是运行时一直提示我 Only one Looper may be created per thread，我好像并没有在一个线程里面开两个handler啊,各位大侠可否帮我看一看。感激不敬
这个是MainActivity
这个是线程
耗时操作的handler
这个是MainActivity
public class MainActivity extends Activity {
private Button caculateButton;
private EditText input;
private TextView output;
private ProgressBar progressBar;
private CaculateThread cacThread;
private Handler mHandler;
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
caculateButton = (Button) findViewById(R.id.caculate);
progressBar = (ProgressBar) findViewById(R.id.process);
input = (EditText) findViewById(R.id.inputView);
output = (TextView) findViewById(R.id.outputView);
// 点击事件将得到数传给子线程去进行计算
caculateButton.setOnClickListener(new OnClickListener() {
@Override
public void onClick(View v) {
int num = Integer.parseInt(input.getText().toString());
Message msg = new Message();
msg.what = 0x123;
Bundle data = new Bundle();
data.putInt("num", num);
progressBar.setMax(num);
progressBar.setMax(0);
progressBar.setProgress(0);
cacThread.getHandler().sendMessage(msg);
}
});
// 当前线程来接收计算线程计算的结果
mHandler = new Handler() {
@Override
public void handleMessage(Message msg) {
if (msg.what == 0x321) {
List<Integer> nums = new ArrayList<Integer>();
nums = (List<Integer>) msg.getData()
.getSerializable("nums");
output.setText(nums.toString());
} else if (msg.what == 0x111) {
int total = msg.getData().getInt("total");
int current = msg.getData().getInt("current");
progressBar.setMax(total);
progressBar.setProgress(current);
}
}
};
cacThread = new CaculateThread(mHandler);
cacThread.run();
}
}这个是线程
public class CaculateThread extends Thread {
private CaculateHandler handler;
private Handler parentHandler;
public CaculateThread(Handler handler) {
// 获取父线程
parentHandler = handler;
}
@Override
public void run() {
Looper.prepare();
this.handler = new CaculateHandler(parentHandler);
Looper.loop();
}
public CaculateHandler getHandler() {
return handler;
}
public void setHandler(CaculateHandler handler) {
this.handler = handler;
}
}耗时操作的handler
public class CaculateHandler extends Handler {
private Handler parentHandler;
private int total = 0;
private int current = 0;
public CaculateHandler(Handler handler) {
parentHandler = handler;
}
@Override
public void handleMessage(Message msg) {
if (msg.what == 0x123) {
int num = msg.getData().getInt("num");
total = num;
List<Integer> nums = new ArrayList<Integer>();
for (int j = 3;; j = j + 2) {
int k = 2;
for (; k < j; k++) {
if (j % k == 0) {
break;
}
}
// 为质数
if (j == k) {
nums.add(j);
current = nums.size();
{
Message procMsg = new Message();
procMsg.what = 0x111;
Bundle data = new Bundle();
data.putInt("total", total);
data.putInt("current", current);
procMsg.setData(data);
// 将消息传给ui线程
parentHandler.sendMessage(procMsg);
}
// 如果达到需要的数量，将质数发送出去
if (nums.size() >= num) {
Message outMsg = new Message();
outMsg.what = 0x321;
Bundle data = new Bundle();
data.putSerializable("nums", (Serializable) nums);
outMsg.setData(data);
// 将消息传给ui线程
parentHandler.sendMessage(outMsg);
}
}
}
}
}
}
...全文
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流浪重耳 2016-08-29
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楼主你和我犯了一样的错误 有可能是对Thread长时间没用了手误将启动线程start换成run start是开启一个线程会穿件Looper实例
run是直接运行run方法当然会出错 基础不牢又不细心中毒很深啊
流浪重耳 2016-08-29
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奇怪了上面代码两个Msg值出错但是修正了还是有这个问题，改成这样就没问题了：
package com.study.touchevent.demo;
import android.app.Activity;
import android.content.Context;
import android.os.Handler;
import android.os.Looper;
import android.os.Message;
import android.support.v7.app.AppCompatActivity;
import android.os.Bundle;
import android.util.Log;
import android.view.Menu;
import android.view.MenuItem;
import android.view.View;
import android.widget.Button;
import android.widget.Toast;
public class MainActivity extends AppCompatActivity {
/**
* 程序说明：
* 主线程发送消息弹出吐司 普通looper线程发送消息弹出吐司
*/
public static final int Msg_MianThread_come=1;
public static final int Msg_LooperThread_Come=2;
private Handler superHandler;
private Handler looperhandler;
private Context mContext;
private Button btn_mian;
private Button bt_normal;
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
mContext = this;
new LooperThread().start();
btn_mian = (Button) findViewById(R.id.btn1);
bt_normal = (Button) findViewById(R.id.btn2);
btn_mian.setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View v) {
if (superHandler != null) {
superHandler.sendEmptyMessage(Msg_MianThread_come);
}
}
});
bt_normal.setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View v) {
if (looperhandler != null) {
looperhandler.sendEmptyMessage(Msg_LooperThread_Come);
}
}
});
superHandler = new Handler() {
@Override
public void handleMessage(Message msg) {
// TODO Auto-generated method stub
super.handleMessage(msg);
int what = msg.what;
switch (what){
case Msg_MianThread_come:
Toast.makeText(mContext, "主线程消息", Toast.LENGTH_LONG).show();
break;
default:
break;
}
}
};
}
/**
* 普通线程
*/
class LooperThread extends Thread {
@Override
public void run() {
// TODO Auto-generated method stub
Looper.prepare();
looperhandler = new Handler() {
@Override
public void handleMessage(Message msg) {
// TODO Auto-generated method stub
super.handleMessage(msg);
int what = msg.what;
switch (what){
case Msg_LooperThread_Come:
Toast.makeText(mContext, "子线程消息", Toast.LENGTH_LONG).show();
break;
default:
break;
}
}
};
Looper.loop();
}
}
}
自己都没发现那个地方有区别
流浪重耳 2016-08-29
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我的也有这个问题
package com.study.touchevent.demo;
import android.content.Context;
import android.os.Handler;
import android.os.Looper;
import android.os.Message;
import android.support.v7.app.AppCompatActivity;
import android.os.Bundle;
import android.util.Log;
import android.view.Menu;
import android.view.MenuItem;
import android.view.View;
import android.widget.Button;
import android.widget.Toast;
public class MainActivity extends AppCompatActivity {
public static final int Msg_MyThread_Come=1;
public static final int Msg_MianThread_come=1;
public Handler handler;
public Handler looperhandler;
public Button btn1;
public Button btn2;
public Context mContex;
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
mContex=this;
new LooperThread().run();
handler=new Handler(){
@Override
public void handleMessage(Message msg) {
super.handleMessage(msg);
int what=msg.what;
switch (what){
case Msg_MianThread_come:
Toast.makeText(mContex,"主线程消息",Toast.LENGTH_LONG).show();
break;
default:
break;
}
}
};
btn1 = (Button) findViewById(R.id.btn1);
btn2 = (Button) findViewById(R.id.btn2);
btn1.setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View v) {
if(handler!=null){
handler.sendEmptyMessage(Msg_MianThread_come);
}
}
});
btn2.setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View v) {
if(looperhandler!=null){
looperhandler.sendEmptyMessage(Msg_MyThread_Come);
}
}
});
}
public class LooperThread extends Thread{
@Override
public void run() {
/* if(Looper.myLooper()!=null){
Looper.prepare();
}*/
Looper.prepare();
looperhandler=new Handler(){
@Override
public void handleMessage(Message msg) {
super.handleMessage(msg);
int what=msg.what;
switch (what){
case Msg_MyThread_Come:
Toast.makeText(mContex,"子线程消息",Toast.LENGTH_LONG).show();
break;
default:
break;
}
}
};
Looper.loop();
}
}
@Override
public boolean onCreateOptionsMenu(Menu menu) {
// Inflate the menu; this adds items to the action bar if it is present.
getMenuInflater().inflate(R.menu.menu_main, menu);
return true;
}
@Override
public boolean onOptionsItemSelected(MenuItem item) {
// Handle action bar item clicks here. The action bar will
// automatically handle clicks on the Home/Up button, so long
// as you specify a parent activity in AndroidManifest.xml.
int id = item.getItemId();
//noinspection SimplifiableIfStatement
if (id == R.id.action_settings) {
return true;
}
return super.onOptionsItemSelected(item);
}
}
boy_nihao 2015-12-10
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楼主现在找到原因了吗 解决了没
boy_nihao 2015-12-10
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刚学looper 我写了个类似的demo并未出现你的问题。
gao_chun 2015-07-29
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你的这个类：public class CaculateThread extends Thread
里头的这个方法 Looper.prepare();
prepare() 这个函数为我们提供初始化Looper对象，这个函数告诉我们只要你调了这个方法，那么系统就会在ThreadLocal内添加一个Looper对象，并且一个线程只能有一个Looper，若超出一个，则会抛出异常.
gao_chun 2015-07-29
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感觉是这里的问题：
@Override
public void run() {
Looper.prepare();
this.handler = new CaculateHandler(parentHandler);
Looper.loop();
}public class Looper {
private static final ThreadLocal sThreadLocal = new ThreadLocal();
final MessageQueue mQueue;
Thread mThread;
private Looper() {
mQueue = new MessageQueue();
mRun = true;
mThread = Thread.currentThread();
}
//调用该方法会在调用线程的TLS中创建Looper对象
public static final void prepare() {
if (sThreadLocal.get() != null) {
//你出现的异常
throw new RuntimeException("Only one Looper may be created per thread");
}
sThreadLocal.set(new Looper());
}
//.....
} 
