Android 中未显示通知标题

Question

我试图从用户那里获取通知的标题，以显示他们何时达到最高值，我这样做了：

 @Override
protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);


    setContentView(R.layout.activity_main);

    minTitle1 = (EditText) findViewById(R.id.minTitle1) ;
  maxTitle1 = (EditText) findViewById(R.id.maxTitle1) ;


   submit.setOnClickListener(new View.OnClickListener() {

        @Override
        public void onClick(View view) {
            try {
                highestText = Integer.parseInt(highest.getText().toString().trim());
                minimumText = Integer.parseInt(minimum.getText().toString().trim());
                minTitle =minTitle1.getText().toString();
                maxTitle=maxTitle1.getText().toString();
            } catch(Exception ex){
                Toast.makeText(getApplicationContext(),"Please enter numbers!",Toast.LENGTH_SHORT).show();
            }
        }
    });

    countUp.setOnClickListener(new View.OnClickListener() {

        @Override
        public void onClick(View view) {
            if(highestText == 0 && minimumText == 0){
                Toast.makeText(getApplicationContext(),"Please enter the target numbers!",Toast.LENGTH_SHORT).show();
            }else {

                if (highestText == count+1 ) {
                    NotificationCompat.Builder builder = new NotificationCompat.Builder(MainActivity.this, "number");
                    builder.setContentTitle(maxTitle);
                    builder.setContentText("please be aware that you reached the maximum number");
                    builder.setSmallIcon(R.drawable.ic_launcher_background);
                    builder.setAutoCancel(true);
                    NotificationManagerCompat managerCompat = NotificationManagerCompat.from(MainActivity.this);
                    managerCompat.notify(1, builder.build());
                }

由于某种原因，通知中没有显示标题。我错过了什么吗？我该如何解决？

Answer 1

对于 android 8.0 及更高版本，您必须像这样创建一个通知通道：

 if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.O) {
    CharSequence name = getString(R.string.channel_name);
    String description = getString(R.string.channel_description);
    int importance = NotificationManager.IMPORTANCE_DEFAULT;
    NotificationChannel channel = new NotificationChannel(CHANNEL_ID, name, importance);
    channel.setDescription(description);
    // Register the channel with the system; you can't change the importance
    // or other notification behaviors after this
    NotificationManager notificationManager = getSystemService(NotificationManager.class);
    notificationManager.createNotificationChannel(channel);
}

从您的代码中可以清楚地看出，当您的最高文本等于 count+1 时，您的通知会弹出，但您正在更新提交按钮中的 maxtitle 值，因此在显示通知时它不会设置为当前的 maxtitle 值。所以 添加 maxTitle=maxTitle1.getText().toString();在你之前 builder.setContentTitle(maxTitle);在您的 countUp 点击时更新您的 maxtitle。

         countUp.setOnClickListener(new View.OnClickListener() {

        @Override
        public void onClick(View view) {
            if(highestText == 0 && minimumText == 0){
                Toast.makeText(getApplicationContext(),"Please enter the target numbers!",Toast.LENGTH_SHORT).show();
            }else {

                if (highestText == count+1 ) {
                    NotificationCompat.Builder builder = new NotificationCompat.Builder(MainActivity.this, "number");
                    maxTitle=maxTitle1.getText().toString();
                    builder.setContentTitle(maxTitle);
                    builder.setContentText("please be aware that you reached the maximum number");
                    builder.setSmallIcon(R.drawable.ic_launcher_background);
                    builder.setAutoCancel(true);
                    NotificationManagerCompat managerCompat = NotificationManagerCompat.from(MainActivity.this);
                    managerCompat.notify(1, builder.build());
                }
        

Answer 2

这里缺少的是频道的创建

在 Android 8.0 及更高版本上发送通知之前，您必须通过将 NotificationChannel 的实例传递给 createNotificationChannel() 来向系统注册应用的通知通道

private fun createNotificationChannel() {
// Create the NotificationChannel, but only on API 26+ because
// the NotificationChannel class is new and not in the support library
if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.O) {
    val name = getString(R.string.channel_name)
    val descriptionText = getString(R.string.channel_description)
    val importance = NotificationManager.IMPORTANCE_DEFAULT
    val channel = NotificationChannel(CHANNEL_ID, name, importance).apply {
        description = descriptionText
    }
    // Register the channel with the system
    val notificationManager: NotificationManager =
        getSystemService(Context.NOTIFICATION_SERVICE) as NotificationManager
    notificationManager.createNotificationChannel(channel)
  }
}

由于您必须在 Android 8.0 及更高版本上发布任何通知之前创建通知通道，因此您应该在应用启动后立即执行此代码。重复调用它是安全的，因为创建现有通知通道不会执行任何操作。

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