targetSdkVersion 23通过accountManager.getAccounts()返回0长度数组

我在真正的Nexus 5设备Android 6.0.1中观察到以下奇怪的结果

我在推出应用程序时运行以下简单代码.

Pattern emailPattern = Patterns.EMAIL_ADDRESS; // API level 8+
AccountManager accountManager = AccountManager.get(this);
Account[] accounts = accountManager.getAccounts();

上面的代码工作正常,如果我将我设置targetSdkVersion为22,21,19.它返回非空数组.

但是,当我改变targetSdkVersion和测试时

defaultConfig {
    applicationId "org.yccheok.myapplication"
    minSdkVersion 19
    targetSdkVersion 23
    versionCode 1
    versionName "1.0"
}

上面的代码返回0长度数组!

知道为什么在编译时会出现问题targetSdkVersion=23.

请注意,在产生问题期间,无论何时更改targetSdkVersion并通过Android Studio运行,您都需要清除应用数据,清除应用缓存并手动卸载所有用户.

以下是在Nexus 5设备Android 6.0.1中重现问题的步骤

通过File - > New - > New Projetct在Android Studio中创建项目...

选择"空白活动"

AndroidManifest.xml中

的build.gradle

apply plugin: 'com.android.application'

android {
    compileSdkVersion 23
    buildToolsVersion "23.0.1"

    defaultConfig {
        applicationId "org.yccheok.myapplication"
        minSdkVersion 19
        targetSdkVersion 23
        versionCode 1
        versionName "1.0"
    }
    buildTypes {
        release {
            minifyEnabled false
            proguardFiles getDefaultProguardFile('proguard-android.txt'), 'proguard-rules.pro'
        }
    }
}

dependencies {
    compile fileTree(dir: 'libs', include: ['*.jar'])
    testCompile 'junit:junit:4.12'
    compile 'com.android.support:appcompat-v7:23.1.1'
    compile 'com.android.support:design:23.1.1'
}

MainActivity.java

import android.accounts.Account;
import android.accounts.AccountManager;
import android.content.pm.ApplicationInfo;
import android.content.pm.PackageInfo;
import android.content.pm.PackageManager;
import android.os.Bundle;
import android.support.design.widget.FloatingActionButton;
import android.support.design.widget.Snackbar;
import android.support.v7.app.AppCompatActivity;
import android.support.v7.widget.Toolbar;
import android.util.Patterns;
import android.view.View;
import android.view.Menu;
import android.view.MenuItem;

import java.util.regex.Pattern;

public class MainActivity extends AppCompatActivity {

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
        Toolbar toolbar = (Toolbar) findViewById(R.id.toolbar);
        setSupportActionBar(toolbar);

        FloatingActionButton fab = (FloatingActionButton) findViewById(R.id.fab);
        fab.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View view) {
                Snackbar.make(view, "Replace with your own action", Snackbar.LENGTH_LONG)
                        .setAction("Action", null).show();
            }
        });

        int targetSdkVersion = 0;
        try {
            PackageInfo packageInfo = getPackageManager().getPackageInfo(getPackageName(), 0);
            targetSdkVersion = packageInfo.applicationInfo.targetSdkVersion;
        }
        catch (PackageManager.NameNotFoundException e) {
            android.util.Log.i("CHEOK", e.getMessage());
        }

        Pattern emailPattern = Patterns.EMAIL_ADDRESS; // API level 8+
        AccountManager accountManager = AccountManager.get(this);
        Account[] accounts = accountManager.getAccounts();

        android.util.Log.i("CHEOK", targetSdkVersion + " : numnber of accoutn by ??? = " + accounts.length);

        for (Account account : accounts) {
            if (emailPattern.matcher(account.name).matches()) {
                String possibleEmail = account.name;
                android.util.Log.i("CHEOK", "possibleEmail = " + possibleEmail);
            }
        }

    }

    @Override
    public boolean onCreateOptionsMenu(Menu menu) {
        // Inflate the menu; this adds items to the action bar if it is present.
        getMenuInflater().inflate(R.menu.menu_main, menu);
        return true;
    }

    @Override
    public boolean onOptionsItemSelected(MenuItem item) {
        // Handle action bar item clicks here. The action bar will
        // automatically handle clicks on the Home/Up button, so long
        // as you specify a parent activity in AndroidManifest.xml.
        int id = item.getItemId();

        //noinspection SimplifiableIfStatement
        if (id == R.id.action_settings) {
            return true;
        }

        return super.onOptionsItemSelected(item);
    }
}

知道为什么targetSdkVersion 23通过accountManager.getAccounts()返回0长度数组