如何在Android上访问短信和电话存储？

Question

I am trying to create an app that reads sms messages and phone calls data so it could provide some information like how much sms/calls did I make in last 24 hours or who is the person that I am texting/talking to the most.

So far I tried to read sms messages using code below but my app keeps crashing.

package com.example.mobilestats

import android.net.Uri
import android.app.Application

class SmsData : Application() {
    private var _smsBodyList = getSMS()


    fun getTotalSmsCount(): Int {
        return _smsBodyList.size
    }

    fun getSMS(): ArrayList<String> {
        var sms = ArrayList<String>()
        var smsURI = Uri.parse("content://sms/inbox")
        var cur = applicationContext.contentResolver.query(smsURI, null, null, null, null)

        while(cur != null && cur.moveToNext()) {
            var body = cur.getString(cur.getColumnIndex("body"))
            sms.add(body)
        }

        if(cur != null) {
            cur.close()
        }
        return sms
    }
}

I think the problem is when I try to make query but I don't get any error report, the application just crashes.

I enabled READ_SMS permission in manifest file.

  <uses-permission android:name="android.permission.READ_SMS"/>

EDIT: I am providing logcat error message.

03-28 17:53:21.709 30686-30686/com.example.mobilestats E/AndroidRuntime: FATAL EXCEPTION: main
    Process: com.example.mobilestats, PID: 30686
    java.lang.RuntimeException: Unable to start activity ComponentInfo{com.example.mobilestats/com.example.mobilestats.MainActivity}: java.lang.NullPointerException: Attempt to invoke virtual method 'android.content.Context android.content.Context.getApplicationContext()' on a null object reference
        at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2572)
        at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2654)
        at android.app.ActivityThread.-wrap11(ActivityThread.java)
        at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1488)
        at android.os.Handler.dispatchMessage(Handler.java:111)
        at android.os.Looper.loop(Looper.java:207)
        at android.app.ActivityThread.main(ActivityThread.java:5728)
        at java.lang.reflect.Method.invoke(Native Method)
        at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:789)
        at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:679)
     Caused by: java.lang.NullPointerException: Attempt to invoke virtual method 'android.content.Context android.content.Context.getApplicationContext()' on a null object reference
        at android.content.ContextWrapper.getApplicationContext(ContextWrapper.java:107)
        at com.example.mobilestats.SmsData.getSMS(SmsData.kt:17)
        at com.example.mobilestats.SmsData.<init>(SmsData.kt:7)
        at com.example.mobilestats.MainActivity.onCreate(MainActivity.kt:17)
        at android.app.Activity.performCreate(Activity.java:6309)
        at android.app.Instrumentation.callActivityOnCreate(Instrumentation.java:1113)
        at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2519)
        at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2654) 
        at android.app.ActivityThread.-wrap11(ActivityThread.java) 
        at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1488) 
        at android.os.Handler.dispatchMessage(Handler.java:111) 
        at android.os.Looper.loop(Looper.java:207) 
        at android.app.ActivityThread.main(ActivityThread.java:5728) 
        at java.lang.reflect.Method.invoke(Native Method) 
        at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:789) 
        at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:679) 

Answer 1

You use READ_SMS permission - it has a protection level dangerous , so you need a runtime request.

if (ContextCompat.checkSelfPermission(this, Manifest.permission.READ_SMS)
        != PackageManager.PERMISSION_GRANTED) {
    ActivityCompat.requestPermissions(this, arrayOf(Manifest.permission.READ_SMS), 0)
} else {
    // Permission already granted
}

For more info you may visit android docs