Java 生成的有符号APK给出NullPointerException

因此，我已经面对这个问题有一段时间了，我到处寻找类似的问题，但我找不到。相信我，当我说我已经尝试了我认为可能相关的大多数方法时。问题是,；当我生成一个签名的APK放在google play商店时，它生成的很好，没有显示错误。当我下载应用程序并登录时，会出现以下错误：

java.lang.NullPointerException:尝试对空对象引用调用虚拟方法“int java.lang.String.length（）”

这很奇怪，因为我的调试APK没有遇到同样的问题

我在android studio中打开了

logCat

，并连接了我的设备，查看它在错误过滤器中显示了哪些消息，我得到了以下信息：

09-28 14:42:25.016 15234-15351/? E/Volley: [9855] g.run: Unhandled exception java.lang.NullPointerException: Attempt to invoke virtual method 'int java.lang.String.length()' on a null object reference
                                       java.lang.NullPointerException: Attempt to invoke virtual method 'int java.lang.String.length()' on a null object reference
                                           at libcore.net.UriCodec.encode(UriCodec.java:132)
                                           at java.net.URLEncoder.encode(URLEncoder.java:57)
                                           at com.a.a.k.a(Unknown Source)
                                           at com.a.a.k.o(Unknown Source)
                                           at com.a.a.a.g.b(Unknown Source)
                                           at com.a.a.a.g.a(Unknown Source)
                                           at com.a.a.a.g.a(Unknown Source)
                                           at com.a.a.a.a.a(Unknown Source)
                                           at com.a.a.g.run(Unknown Source)
09-28 14:42:25.136 15234-15234/? E/MainActivity: Login Error: 
java.lang.NullPointerException: Attempt to invoke virtual method 'int 
java.lang.String.length()' on a null object reference
09-28 14:42:25.176 1425-1425/? E/KeyboardInfoUtils: getInstance start
09-28 14:42:25.176 1425-1425/? E/KeyboardInfoUtils: sendSIPInformation 
state:6  isAbstractKeyboardView : true
09-28 14:42:25.176 1425-1425/? E/KeyboardInfoUtils: sending null 
keyboardInfo as SIP is closed
09-28 14:42:25.286 164-164/? E/BufferQueueCore: [Toast] 
setDefaultMaxBufferCount: setting count to 3, previous is 2 

这也是我的

build.gradle

文件：

apply plugin: 'com.android.application'

android {
signingConfigs {
    config {
        keyAlias 'release-config'
        keyPassword '***********'
    }
}
compileSdkVersion 25
buildToolsVersion "25.0.3"
defaultConfig {
    applicationId "co.uk.mednet.mednet_ghana"
    minSdkVersion 20
    targetSdkVersion 25
    versionName '1.0.1'
    testInstrumentationRunner "android.support.test.runner.AndroidJUnitRunner"
    multiDexEnabled true
    versionNameSuffix '1.0.5'
    versionCode 1016
}
buildTypes {
    release {
        minifyEnabled true
        proguardFiles getDefaultProguardFile('proguard-android.txt'), 'proguard-rules.pro'
    }
}
sourceSets { main { assets.srcDirs = ['src/main/assets', 'src/main/assets/'] } }
productFlavors {
}
 }

dependencies {
compile fileTree(include: ['*.jar'], dir: 'libs')
androidTestCompile('com.android.support.test.espresso:espresso-core:2.2.2', {
    exclude group: 'com.android.support', module: 'support-annotations'
})
compile 'com.android.support:appcompat-v7:25.3.1'
compile 'com.android.support:design:25.3.1'
compile 'com.android.support:support-v4:25.3.1'
compile 'com.android.support:recyclerview-v7:25.3.1'
compile 'com.android.support:support-core-utils:25.3.1'
compile 'org.androidannotations:androidannotations-api:4.0.0'
compile 'com.mcxiaoke.volley:library-aar:1.0.0'
compile 'com.loopj.android:android-async-http:1.4.9'
compile 'com.google.code.gson:gson:2.7'
compile 'com.android.support.constraint:constraint-layout:1.0.2'
compile 'com.github.barteksc:android-pdf-viewer:2.6.1'
compile 'com.android.support:support-v13:25.3.1'
compile 'com.github.markushi:circlebutton:1.1'
testCompile 'junit:junit:4.12'
provided 'org.androidannotations:androidannotations:4.0.0'
}
android {
lintOptions {
    checkReleaseBuilds false
    abortOnError false
}
}

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