“如何在启用 Button 的同时进行 CountDown 显示？”关于按钮的附加信息：按钮作业是通过 Textview 中显示的字符串数组单击 5 次，然后禁用 5 秒钟以再次执行相同的任务。所以..我想要一个倒计时来直观地显示那些 5 秒（按钮启用的时间）倒计时供用户查看。遗憾的是，我不知道如何将我的 Button 与 CountDown 连接起来，让它知道它应该在启用 Button 的特定时间倒计时。此外，我希望每次启用按钮时都开始倒计时。我查看了https://developer.android.com/reference/android/os/CountDownTimer 但它似乎没有针对该特定情况的解决方案。这就是我现在的按钮代码：next_button.setOnClickListener(new View.OnClickListener() { @Override public void onClick(View v) { if (currentnumber == list.length) { currentnumber = 0; } if (Curclicks == mod - 1) { next_button.setEnabled(false); display.setText(list[currentnumber]); currentnumber++; handler.postDelayed(new Runnable() { @Override public void run() { //the button will unlock after the delay specified next_button.setEnabled(true); Curclicks = 0; } }, delay); } else { display.setText(list[currentnumber]); currentnumber++; } Curclicks++; } });UI Thread 代码可以解决吗？： private void runThread() { new Thread() { public void run() { while (delay == 5000) { //delay = 5000 ( 5 secs) try { runOnUiThread(new Runnable() { @Override public void run() { timer.setText("" + delay);//timer=TxtView } }); Thread.sleep(300); } catch (InterruptedException e) { e.printStackTrace(); } } } }.start();
3 回答
慕的地10843
TA贡献1785条经验 获得超8个赞
下面是一个示例，说明如何使用 的postDelayed()方法Handler创建倒计时。我特意把代码留得有点冗长，这样你就可以一步一步地浏览它，看看发生了什么。
创建一些类变量和常量。
private static final long COUNT_DOWN_TICKS = 100l;
private static final long COUNT_DOWN_FINISH = 5000l;
private long countdownElapsed = 0l;
private Handler mCountDownHandler = new Handler();
COUNT_DOWN_FINISH设置为 5000 --> 5 秒。但可以更改为您需要的任何内容。我还使用COUNT_DOWN_TICKSset 为 100 --> 0.1 秒，以防万一您想显示更精确的倒计时。
从您的OnClick()方法中只需调用startCountDown()即可开始倒计时。
private void startCountDown() {
try {
countdownElapsed = 0l;
next_button.setEnabled(false);
displayCountDown();
mCountDownHandler.postDelayed(mCountDownRunnable, COUNT_DOWN_TICKS);
}
catch (Exception ex){
Log.e(TAG, ex.getMessage());
}
}
private Runnable mCountDownRunnable = new Runnable() {
@Override
public void run() {
countdownElapsed = countdownElapsed + COUNT_DOWN_TICKS;
if(countdownElapsed >= COUNT_DOWN_FINISH){
releaseCountDownHandler();
next_button.setEnabled(true);
}
else{
mCountDownHandler.postDelayed(mCountDownRunnable, COUNT_DOWN_TICKS);
}
long secFull = countdownElapsed % 1000;
if(secFull == 0){
runOnUiThread(new Runnable() {
@Override
public void run() {
displayCountDown();
}
});
}
}
};
private void releaseCountDownHandler() {
try {
if(mCountDownRunnable != null) {
mCountDownHandler.removeCallbacks(mCountDownRunnable);
}
}
catch (Exception ex){
Log.e(TAG, ex.getMessage());
}
}
private void displayCountDown(){
long t = (COUNT_DOWN_FINISH - countdownElapsed)/1000;
String myTime = String.valueOf(t);
timer.setText(myTime);
}
为了Runnable正确处理，您需要releaseCountDownHandler()从onPause()方法中调用。这只是一个短暂的运行Thread，但它仍然不应该被忽视。
我更喜欢HandlerwithpostDelay()方法而不是Thread.sleep()方法——让任何线程进入睡眠状态的事情令人不安。另请注意，习惯于使用“>=”而不是“==”检查经过时间条件是个好主意，具体取决于实现（例如，您SystemClock.elapsedRealtime()改为使用）条件可能会错过确切的值！
编辑
在您的Activity类定义下的某处（在本例中，我将称之为MainActivity）您需要声明一些变量。由于它们是在类内部而不是在方法内部定义的，因此它们被称为“类变量”，并且在定义为“私有”时具有整个类的范围。
public class MainActivity extends AppCompatActivity {
//class variables
private static final long COUNT_DOWN_TICKS = 100l;
private static final long COUNT_DOWN_FINISH = 5000l;
private long countdownElapsed = 0l;
private Handler mCountDownHandler = new Handler();
private Button next_button;
private TextView timer;
....
}
您可能已经在类onClick()的onCreate()方法中声明了该方法MainActivity。所以只需添加以下代码：
next_button.setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View v) {
startCountDown();
}
我提供的所有其他方法都是MainActivity类中的方法……而不是任何其他方法中的方法。所以在onCreate()方法下面添加我之前发布的所有方法。
它看起来像这样：
public class MainActivity extends AppCompatActivity {
private static final String TAG = MainActivity.class.getSimpleName();
//class variables
private static final long COUNT_DOWN_TICKS = 100l;
private static final long COUNT_DOWN_FINISH = 5000l;
private long countdownElapsed = 0l;
private Handler mCountDownHandler = new Handler();
private Button next_button;
private TextView timer;
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
// you must compensate for the actual layout for your activity
setContentView(R.layout.activity_main);
// you must compensate for the actual id of the TextView
timer = findViewById(R.id.tvTimer);
// you must compensate for the actual id of the Button
next_button = findViewById(R.id.btnNext);
next_button.setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View v) {
startCountDown();
}
});
}
private void startCountDown() {
try {
countdownElapsed = 0l;
next_button.setEnabled(false);
displayCountDown();
mCountDownHandler.postDelayed(mCountDownRunnable, COUNT_DOWN_TICKS);
}
catch (Exception ex){
Log.e(TAG, ex.getMessage());
}
}
private Runnable mCountDownRunnable = new Runnable() {
@Override
public void run() {
countdownElapsed = countdownElapsed + COUNT_DOWN_TICKS;
if(countdownElapsed >= COUNT_DOWN_FINISH){
releaseCountDownHandler();
next_button.setEnabled(true);
}
else{
mCountDownHandler.postDelayed(mCountDownRunnable, COUNT_DOWN_TICKS);
}
long secFull = countdownElapsed % 1000;
if(secFull == 0){
runOnUiThread(new Runnable() {
@Override
public void run() {
displayCountDown();
}
});
}
}
};
private void releaseCountDownHandler() {
try {
if(mCountDownRunnable != null) {
mCountDownHandler.removeCallbacks(mCountDownRunnable);
}
}
catch (Exception ex){
Log.e(TAG, ex.getMessage());
}
}
private void displayCountDown(){
long t = (COUNT_DOWN_FINISH - countdownElapsed)/1000;
String myTime = String.valueOf(t);
timer.setText(myTime);
}
}
繁星淼淼
TA贡献1775条经验 获得超11个赞
这段代码就像我上面的代码，除了这段代码引入了一个“点击计数器”。我引入了一个新的类变量来跟踪按钮被点击的次数。我还引入了一个名为“NUMBER_OF_BUTTON_CLICKS”的新常量，它作为点击次数的上限。
用户现在可以点击按钮（在本例中）5 次。第 5 次单击时，满足触发startCountDown方法的条件并且按钮被禁用 5 秒。
public class MainActivity extends AppCompatActivity {
//Constant values
private static final String TAG = MainActivity.class.getSimpleName();
private static final int NUMBER_OF_BUTTON_CLICKS = 5;
private static final long COUNT_DOWN_TICKS = 100l;
private static final long COUNT_DOWN_FINISH = 5000l;
//class variables
private int howManyClicks = 0;
private long countdownElapsed = 0l;
private Handler mCountDownHandler = new Handler();
private Button next_button;
private TextView timer;
private TextView clicks;
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
// you must compensate for the actual layout for your activity
setContentView(R.layout.activity_main);
// you must compensate for the actual id of the TextView
timer = findViewById(R.id.tvTimer);
// Use this only if you want to display the number of clicks
// you might need to add this TextView if you want to display the number of clicks
clicks = findViewById(R.id.tvClicks);
// you must compensate for the actual id of the Button
next_button = findViewById(R.id.btnNext);
next_button.setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View v) {
howManyClicks++;
if(howManyClicks >= NUMBER_OF_BUTTON_CLICKS){
startCountDown();
}
//Add this only if you want to see how many clicks were made
String myClicks = String.valueOf(howManyClicks);
clicks.setText(myClicks)
}
});
}
private void startCountDown() {
try {
countdownElapsed = 0l;
next_button.setEnabled(false);
displayCountDown();
mCountDownHandler.postDelayed(mCountDownRunnable, COUNT_DOWN_TICKS);
}
catch (Exception ex){
Log.e(TAG, ex.getMessage());
}
}
private Runnable mCountDownRunnable = new Runnable() {
@Override
public void run() {
countdownElapsed = countdownElapsed + COUNT_DOWN_TICKS;
if(countdownElapsed >= COUNT_DOWN_FINISH){
releaseCountDownHandler();
next_button.setEnabled(true);
// reset the clicks counter
howManyClicks = 0;
}
else{
mCountDownHandler.postDelayed(mCountDownRunnable, COUNT_DOWN_TICKS);
}
long secFull = countdownElapsed % 1000;
if(secFull == 0){
runOnUiThread(new Runnable() {
@Override
public void run() {
displayCountDown();
}
});
}
}
};
private void releaseCountDownHandler() {
try {
if(mCountDownRunnable != null) {
mCountDownHandler.removeCallbacks(mCountDownRunnable);
}
}
catch (Exception ex){
Log.e(TAG, ex.getMessage());
}
}
private void displayCountDown(){
long t = (COUNT_DOWN_FINISH - countdownElapsed)/1000;
String myTime = String.valueOf(t);
timer.setText(myTime);
//Add this only if you want to see how many clicks were made
String myClicks = String.valueOf(howManyClicks);
clicks.setText(myClicks)
}
}
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