尝试在空对象引用上调用虚拟方法的android.graphics.drawable.Drawable android.graphics.drawable.Drawable

Question

在某些设备上，我会崩溃，而在大多数设备上，一切正常，谁能解释这种异常的原因以及如何修复呢？

我的代码：

private fun onGetBatteryApps() {
        mBatteryAppsBinding.batteryAnim.playAnimation()
        val pm: PackageManager = requireActivity().packageManager
        val apps: List<PackageInfo> = requireActivity().packageManager.getInstalledPackages(
            PackageManager.GET_META_DATA)

        val rem = apps.filter { pm.getLaunchIntentForPackage(it.packageName) != null && it.packageName != BuildConfig.APPLICATION_ID}

        var j = 0
        timer = object : CountDownTimer(300, 300) {
            override fun onTick(millisUntilFinished: Long) {}
            override fun onFinish() {
                if (rem[j].packageName != BuildConfig.APPLICATION_ID) {
                    mBatteryAppsBinding.appName.text =
                        activity?.application?.packageManager?.let {rem[j].applicationInfo.loadLabel(it).toString()
                        }
                    if (rem[j].applicationInfo.loadIcon(activity?.application?.packageManager) != null) {
                        mBatteryAppsBinding.appIcon.setImageDrawable(rem[j].applicationInfo.loadIcon(activity?.application?.packageManager))
                    } else {
                        mBatteryAppsBinding.appIcon.setImageDrawable(resources.getDrawable(R.drawable.ic_android_white_24dp))
                    }
                    j++
                    if (j == rem.size - 1) j = 0
                    start()
                }

            }

        }.start()
    }

我的日志：

Fatal Exception: java.lang.NullPointerException: Attempt to invoke virtual method 'android.graphics.drawable.Drawable android.content.pm.PackageManager.loadItemIcon(android.content.pm.PackageItemInfo, android.content.pm.ApplicationInfo)' on a null object reference
       at android.content.pm.PackageItemInfo.loadIcon(PackageItemInfo.java:269)
       at com.myapplication.applicationname.view.fragment.BatteryAppsFragment$onGetBatteryApps$1.onFinish(BatteryAppsFragment.java:2)
       at android.os.CountDownTimer$1.handleMessage(CountDownTimer.java:127)
       at android.os.Handler.dispatchMessage(Handler.java:110)
       at android.os.Looper.loop(Looper.java:219)
       at android.app.ActivityThread.main(ActivityThread.java:8393)
       at java.lang.reflect.Method.invoke(Method.java)
       at com.android.internal.os.RuntimeInit$MethodAndArgsCaller.run(RuntimeInit.java:513)
       at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:1055)

根据Crashlytics中的数据，这可以发生在任何设备和Android版本上。

Answer 1

如果您的应用程序在设备低SDK (如Lollipop )方面有问题，那么我就有解决方案了。您需要从您的.png复制所有图像( drawable )，并将它们粘贴到drawable v24中。希望能帮上忙。如果你有什么问题。让我知道