Question

我制作了一个小应用程序，它以TimePicker的形式接收来自用户的输入，并将其存储在变量中，这些变量随后用于触发警报，从而使振铃器保持在所需的模式，直到需要为止。

但是每次我尝试在AVD上运行它时，只要我按下无声或振动的任何按钮，它就会不断崩溃。

MainActivity.java文件：

package com.example.android.implementingringermechanism;

import android.app.AlarmManager;
import android.app.PendingIntent;
import android.content.Context;
import android.content.Intent;
import android.media.AudioManager;    
import android.os.Build;
import android.support.v7.app.AppCompatActivity;
import android.os.Bundle;
import android.view.View;
import android.widget.Button;
import android.widget.TimePicker;
import android.widget.Toast;

import java.util.Calendar;

public class MainActivity extends AppCompatActivity {

//TimePicker to take time input from user when dialog activity pops
TimePicker picker;
//Buttons to change mode to silent or vibrate
Button silentButton, vibrateButton;
//Variables to store hours and minutes chosen by user
private int hour, minute;

//AudioManager instance used to change ringer mode
private AudioManager mAudioManager;

//AlarmManager instance used to set alarm to background task
AlarmManager mgr;

//Calendar instance to manipulate time for alarm with user input
Calendar time;

//PendingIntent to start when alarm is finished
private PendingIntent pendingIntent;

@Override
protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.activity_main);
    picker = (TimePicker) findViewById(R.id.timePicker);
    //TimePicker will show time in 24 hour mode
    picker.setIs24HourView(true);
    silentButton = (Button) findViewById(R.id.silentButton);
    vibrateButton = (Button) findViewById(R.id.vibrateButton);

    //AlarmManager instance created to set an alarm for changing ringer mode back to normal
    mgr = (AlarmManager)getSystemService(Context.ALARM_SERVICE);
    Intent intent = new Intent(this, MyAlarmReceiver.class);
    pendingIntent = PendingIntent.getBroadcast(this, 0, intent, 0);
    time = Calendar.getInstance();
    time.setTimeInMillis(System.currentTimeMillis());

}

public void silent(View view){
    if(Build.VERSION.SDK_INT >= 23){
        hour = picker.getHour();
        minute = picker.getMinute();
    }
    else {
        hour = picker.getCurrentHour();
        minute = picker.getCurrentMinute();
    }
    mAudioManager.setRingerMode(AudioManager.RINGER_MODE_SILENT);
    Toast.makeText(this, "Silent mode till " + hour + ":" + minute, Toast.LENGTH_LONG).show();
    time.add(Calendar.HOUR, hour);
    time.add(Calendar.MINUTE, minute);
    mgr.set(AlarmManager.RTC_WAKEUP, time.getTimeInMillis(), pendingIntent);
}

public void vibrate(View view) {
    if(Build.VERSION.SDK_INT >= 23){
        hour = picker.getHour();
        minute = picker.getMinute();
    }
    else {
        hour = picker.getCurrentHour();
        minute = picker.getCurrentMinute();
    }
    mAudioManager.setRingerMode(AudioManager.RINGER_MODE_VIBRATE);
    Toast.makeText(this, "Vibrate mode till " + hour + ":" + minute, Toast.LENGTH_LONG).show();
    time.add(Calendar.HOUR, hour);
    time.add(Calendar.MINUTE, minute);
    mgr.set(AlarmManager.RTC_WAKEUP, time.getTimeInMillis(), pendingIntent);

}
}

activity_main.xml文件：

<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:app="http://schemas.android.com/apk/res-auto"
xmlns:tools="http://schemas.android.com/tools"
android:layout_width="match_parent"
android:layout_height="wrap_content"
tools:context=".MainActivity"
android:layout_gravity="center"
android:orientation="vertical"
>

<TimePicker
    android:id="@+id/timePicker"
    android:layout_width="273dp"
    android:layout_height="368dp"
    android:layout_marginLeft="40dp" />

<LinearLayout
    android:layout_width="wrap_content"
    android:layout_height="wrap_content"
    android:orientation="horizontal">
    <Button
        android:id="@+id/silentButton"
        android:layout_height="wrap_content"
        android:layout_width="wrap_content"
        android:layout_marginLeft="40dp"
        android:text="@string/silentText"
        android:textStyle="bold"
        android:onClick="silent"/>
    <Button
        android:id="@+id/vibrateButton"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:layout_marginLeft="100dp"
        android:text="@string/vibrateText"
        android:textStyle="bold"
        android:onClick="vibrate"
        />


</LinearLayout>
</LinearLayout>

AndroidManifest.xml文件：

<?xml version="1.0" encoding="utf-8"?>
<manifest xmlns:android="http://schemas.android.com/apk/res/android"
package="com.example.android.implementingringermechanism">

<application
    android:allowBackup="true"
    android:icon="@mipmap/ic_launcher"
    android:label="@string/setTime"
    android:roundIcon="@mipmap/ic_launcher_round"
    android:supportsRtl="true"
    android:theme="@style/Theme.AppCompat.Dialog">
    <activity android:name=".MainActivity">
        <intent-filter>
            <action android:name="android.intent.action.MAIN" />

            <category android:name="android.intent.category.LAUNCHER" />
        </intent-filter>
    </activity>
    <receiver android:name=".MyAlarmReceiver" />
</application>
<uses-permission android:name="android.permission.ACCESS_NOTIFICATION_POLICY" />
</manifest>

MyAlarmReceiver.java文件：

package com.example.android.implementingringermechanism;

import android.content.BroadcastReceiver;
import android.content.Context;
import android.content.Intent;
import android.media.AudioManager;
import android.widget.Toast;

class MyAlarmReceiver extends BroadcastReceiver{

private AudioManager AM;

@Override
public void onReceive(Context context, Intent intent){
    AM.setRingerMode(AudioManager.RINGER_MODE_NORMAL);
    Toast.makeText(context, "Ringer Mode changed to Normal", Toast.LENGTH_LONG).show();

}

}

目前，我遇到的问题是在应用启动时出现对话框，但是按下两个按钮中的任何一个都会使其崩溃。

Answer 1

先生，如果您要在更高版本的android API上进行测试，则需要先添加询问管理员的权限

    private void fornougat() {

    NotificationManager notificationManager =
            (NotificationManager) getSystemService(NOTIFICATION_SERVICE);

    if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.N
            && !notificationManager.isNotificationPolicyAccessGranted()) {
        Toast.makeText(this, R.string.permission, Toast.LENGTH_SHORT).show();
        Intent intent = new Intent(
                android.provider.Settings
                        .ACTION_NOTIFICATION_POLICY_ACCESS_SETTINGS);

        startActivity(intent);
    }
}

Answer 2

您的代码无法正常运行有两个原因：

您的AudioManager为空。将此代码添加到您的onCreate（）中：

mAudioManager =（AudioManager）getSystemService（Context.AUDIO_SERVICE）;

如果要在运行Android Marshmallow或更高版本的设备上进行测试，则需要先向用户请求权限，然后才能设置铃声模式。您可以通过添加以下代码来获得该请求：

NotificationManager notificationManager = (NotificationManager) getSystemService(NOTIFICATION_SERVICE);

if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.M 
        && !notificationManager.isNotificationPolicyAccessGranted()) {
    startActivity(new Intent(Settings.ACTION_NOTIFICATION_POLICY_ACCESS_SETTINGS));
}

铃声模式更改应用程序无法按预期工作

2 个答案: