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我在新的Android工作室版本中得到以下错误基本的hello世界也没有建立在gradle中.云请你帮忙.

这是我在新的android studio版本中遇到的错误:

我的gradle文件如下

apply plugin: 'com.android.application'

android {
    compileSdkVersion 28
    defaultConfig {
        applicationId "payments.com.java.payments"
        minSdkVersion 17
        targetSdkVersion 28
        versionCode 1
        versionName "1.0"
        testInstrumentationRunner "android.support.test.runner.AndroidJUnitRunner"
    }
    buildTypes {
        release {
            minifyEnabled false
            proguardFiles getDefaultProguardFile('proguard-android.txt'), 'proguard-rules.pro'
        }
    }
}

dependencies {
    implementation fileTree(dir: 'libs', include: ['*.jar'])
    implementation 'com.android.support:appcompat-v7:28.0.0-rc01'
    implementation 'com.android.support.constraint:constraint-layout:1.1.2'
    testImplementation 'junit:junit:4.12'
    androidTestImplementation 'com.android.support.test:runner:1.0.2'
    androidTestImplementation 'com.android.support.test.espresso:espresso-core:3.0.2'
}

这是我得到的日志

无法解析':app @ debug/compileClasspath'的依赖关系:无法解析com.android.support:appcompat-v7:28.0.0-rc01.打开文件显示细节

无法解析':app @ debug/compileClasspath'的依赖关系:无法解析com.android.support.constraint:constraint-layout:1.1.2.打开文件显示细节

无法解析':app @ debugAndroidTest/compileClasspath'的依赖关系:无法解析com.android.support.test:runner:1.0.2.打开文件显示细节

无法解析':app @ debugAndroidTest/compileClasspath'的依赖关系:无法解析com.android.support.test.espresso:espresso-core:3.0.2.打开文件显示细节

无法解析':app @ debugAndroidTest/compileClasspath'的依赖关系:无法解析com.android.support:appcompat-v7:28.0.0-rc01.打开文件显示细节

无法解析':app @ debugAndroidTest/compileClasspath'的依赖关系:无法解析com.android.support.constraint:constraint-layout:1.1.2.打开文件显示细节

无法解析':app @ debugUnitTest/compileClasspath'的依赖关系:无法解析com.android.support:appcompat-v7:28.0.0-rc01.打开文件显示细节

无法解析':app @ …

我正在尝试连接到 mongodb，但出现以下错误，请帮忙

var mongo = require('mongodb').MongoClient;
mongo.connect('mongodb://usernamexyz:passwordxyz@hostmxy-mw-e6-u1238.nam.nsroot.net:47017/sampleDB?replicaSet=NAME_2436&readPreference=primary&authSource=admin&w=1', { useNewUrlParser: true, useUnifiedTopology: true  })
.then(() => console.log("Mongodb connected"))
.catch(err => console.log(err));

我得到的错误如下

MongoServerSelectionError: connection <monitor> to 155.30.360.129:37017 closed
    at Timeout._onTimeout (C:\Fintech\NodeFirstApp\node_modules\mongodb\lib\core\sdam\topology.js:448:30)
    at listOnTimeout (internal/timers.js:531:17)
    at processTimers (internal/timers.js:475:7) {
  name: 'MongoServerSelectionError',
  reason: TopologyDescription {
    type: 'ReplicaSetNoPrimary',
    setName: null,
    maxSetVersion: null,
    maxElectionId: null,
    servers: Map {
      'hostmxy-mw-e6-u1238.nam.nsroot.net:47017' => [ServerDescription]
    },
    stale: false,
    compatible: true,
    compatibilityError: null,
    logicalSessionTimeoutMinutes: null,
    heartbeatFrequencyMS: 10000,
    localThresholdMS: 15,
    commonWireVersion: null
  },
  [Symbol(mongoErrorContextSymbol)]: {}
}