我正在使用一个线程来运行 5 秒的计时器，当该计时器用完时，我想更改一些变量并再次启动它，重复此过程直到不满足特定条件。我一直在研究线程，显然它们不能被重置或再次使用，但必须创建另一个线程。我想不出正确的方法。
这是我的代码:
package com.deucalion0;
import android.app.Activity;
import android.content.Intent;
import android.media.MediaPlayer;
import android.os.Bundle;
import android.view.View;
import android.widget.Button;
import android.widget.TextView;
public class FirstOneActivity extends Activity {
/** Called when the activity is first created. */
MediaPlayer ourSong;
int counter;
Button add;
Thread timer;
TextView display;
TextView lvl;
int level = 1;
int time;
@Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.main);
ourSong = MediaPlayer.create(FirstOneActivity.this, R.raw.click);
counter = 0;
add = (Button) findViewById (R.id.bAdd);
display = (TextView) findViewById (R.id.tvDisplay);
lvl = (TextView) findViewById (R.id.lvldisplay);
add.setOnClickListener(new View.OnClickListener() {
public void onClick(View v) {
// TODO Auto-generated method stub
counter++;
//ourSong.start();
display.setText("Your total is "+ counter);
if(counter ==1)
{
set();
}
}
});
timer = new Thread(){
public void run(){
try{
sleep(time);
}catch(InterruptedException e){
e.printStackTrace();
}finally{
test();
}
}
};
}
public void test(){ // Method that does two things after the timer runs out, depending on the value held in counter
if(counter>= 10 && level == 1 || counter>= 15 && level == 2)
{
level++;
counter =0;
display.setText("Your total is 0");
//The timer must be reset for the next level
}
else if(counter<10 && level == 1 || counter< 15 && level == 2){
Intent openNext = new Intent("com.deucalion0.NEXT");
startActivity(openNext);
}
}
public void set(){
if(level == 1)
{ lvl.setText("Level is "+ level);
time = 5000; // The value passed to the sleep method in the thread, this is the length of the timer
}
else if (level == 2)
{lvl.setText("Level is "+level);
time = 5000;
}
}
}
所以基本上我想继续使用该线程，但根据级别为它传递不同的时间限制，为了测试我现在只编写了前两个级别。
如果对此有任何见解，我将不胜感激。谢谢。
我的代码的修订版使用了此处答案中的一些帮助，但我仍然遇到问题:
package com.deucalion0;
import android.app.Activity;
import android.content.Intent;
import android.media.MediaPlayer;
import android.os.Bundle;
import android.os.Handler;
import android.view.View;
import android.widget.Button;
import android.widget.TextView;
public class FirstOneActivity extends Activity {
/** Called when the activity is first created. */
MediaPlayer ourSong;
int counter;
Button add;
Thread timer;
TextView display;
TextView lvl;
int level = 1;
int time;
boolean completed = false;
@Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.main);
ourSong = MediaPlayer.create(FirstOneActivity.this, R.raw.click);
counter = 0;
add = (Button) findViewById (R.id.bAdd);
display = (TextView) findViewById (R.id.tvDisplay);
lvl = (TextView) findViewById (R.id.lvldisplay);
add.setOnClickListener(new View.OnClickListener() {
public void onClick(View v) {
// TODO Auto-generated method stub
counter++;
completed=false;
//ourSong.start();
display.setText("Your total is "+ counter);
if(counter ==1)
{
set();
timer.start(); // start the timer loop:
}
}
});
// create a Handler for the thread to use when interacting with the UI
final Handler handler = new Handler();
// create the timer object
timer = new Thread() {
public void run() {
// create a Runnable that will execute on the UI thread
Runnable updater = new Runnable() {
public void run() {
}
};
while (!completed) {
try {
sleep(time);
} catch(InterruptedException e) {
e.printStackTrace();
} finally {
handler.post(updater);
test();
}
}
}
};
}
public void reset()//Resets the variables so the level increments, the counter is reset to 0
{
completed=true;
level++;
counter =0;
}
public void test(){ // Method that does two things after the timer runs out, depending on the value held in counter
if(counter>= 10 && level == 1 || counter>= 15 && level == 2)
{
reset();
}
else if(counter<10 && level == 1 || counter< 15 && level == 2){
Intent openNext = new Intent("com.deucalion0.NEXT");
startActivity(openNext);
}
}
public void set(){
if(level == 1)
{ lvl.setText("Level is "+ level);
time = 5000; // The value passed to the sleep method in the thread, thi is the length of the timer
}
else if (level == 2)
{lvl.setText("Level is "+level);
time = 5000;
}
}
}
游戏运行并在计数器 = 1 时启动计时器，但如果我在计时器用完后按下按钮，我会由于异常而强制关闭。我需要做的是，如果在 5 秒内按下超过 9 次点击，计数器将重置为 0，级别变为 2。以下是 LogCat 中的错误:
02-29 09:47:36.313: D/AndroidRuntime(279): Shutting down VM
02-29 09:47:36.313: W/dalvikvm(279): threadid=1: thread exiting with uncaught exception (group=0x4001d800)
02-29 09:47:36.333: E/AndroidRuntime(279): FATAL EXCEPTION: main
02-29 09:47:36.333: E/AndroidRuntime(279): java.lang.IllegalThreadStateException: Thread already started.
02-29 09:47:36.333: E/AndroidRuntime(279): at java.lang.Thread.start(Thread.java:1322)
02-29 09:47:36.333: E/AndroidRuntime(279): at com.deucalion0.FirstOneActivity$1.onClick(FirstOneActivity.java:51)
02-29 09:47:36.333: E/AndroidRuntime(279): at android.view.View.performClick(View.java:2408)
02-29 09:47:36.333: E/AndroidRuntime(279): at android.view.View$PerformClick.run(View.java:8816)
02-29 09:47:36.333: E/AndroidRuntime(279): at android.os.Handler.handleCallback(Handler.java:587)
02-29 09:47:36.333: E/AndroidRuntime(279): at android.os.Handler.dispatchMessage(Handler.java:92)
02-29 09:47:36.333: E/AndroidRuntime(279): at android.os.Looper.loop(Looper.java:123)
02-29 09:47:36.333: E/AndroidRuntime(279): at android.app.ActivityThread.main(ActivityThread.java:4627)
02-29 09:47:36.333: E/AndroidRuntime(279): at java.lang.reflect.Method.invokeNative(Native Method)
02-29 09:47:36.333: E/AndroidRuntime(279): at java.lang.reflect.Method.invoke(Method.java:521)
02-29 09:47:36.333: E/AndroidRuntime(279): at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:868)
02-29 09:47:36.333: E/AndroidRuntime(279): at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:626)
02-29 09:47:36.333: E/AndroidRuntime(279): at dalvik.system.NativeStart.main(Native Method)
我希望这些信息有助于说明我的问题。
最佳答案
作为一般规则，Thread 对象可以start() 调用任意多次。每次调用 start() 都会启动一个新线程。其他类似线程的对象(例如 AsyncTask 、 TimerTask )通常只能执行一次。
但是，您的计时器线程不会像写的那样工作。 test()方法修改显示，需要在UI线程上运行。
一种方法是创建一个 Handler并从计时器线程向处理程序发送一个 Runnable，然后处理程序调用 test()。还有其他方法，但这个方法可能涉及对现有代码的最少修改。
你应该考虑使用 AsyncTask 来做你想做的事。您还应该启用 StrictMode在开发时帮助检测任何线程错误。
这是对您的代码的简单修改，它将完成我认为您正在尝试做的事情:
// create a Handler for the thread to use when interacting with the UI
final Handler handler = new Handler();
// create the timer object
timer = new Thread() {
public void run() {
// create a Runnable that will execute on the UI thread
Runnable updater = new Runnable() {
public void run() {
test();
}
}
while (!exitConditionMet()) {
try {
sleep(time);
} catch(InterruptedException e) {
e.printStackTrace();
} finally {
handler.post(updater);
}
}
}
};
// start the timer loop:
timer.start();
上面的代码假定有一个方法 exitConditionMet() 在线程应该退出时返回 true。
关于android - Android中一个线程可以重复使用吗？，我们在Stack Overflow上找到一个类似的问题： https://stackoverflow.com/questions/9486971/