butterknife: Quoting Butter Knife 8.8.1 in the library, using BindView in the app module, but the view appears NullPointerException

I used a butterknife 8.8.1 in AndroidStudio3.0。 My project gradle：

buildscript {
    repositories {
        jcenter()
        ......
        mavenCentral()
        maven { url "https://oss.sonatype.org/content/repositories/snapshots" }
    }
    dependencies {
        classpath 'com.android.tools.build:gradle:3.0.0'
        classpath 'com.jakewharton:butterknife-gradle-plugin:9.0.0-SNAPSHOT'
    }
}
allprojects {
    repositories {
        jcenter()
        ......
        maven { url "https://oss.sonatype.org/content/repositories/snapshots" }
        google()
    }
}

In my app module gradle:

......
apply plugin: 'com.jakewharton.butterknife'

In my Library module gradle:

apply plugin: 'com.android.library'
dependencies {
    ......
    compile "com.jakewharton:butterknife:${butterknifeSdkVersion}"
    annotationProcessor "com.jakewharton:butterknife-compiler:${butterknifeSdkVersion}"
}

In my app module activity binding View, @ BindView (R.id.xx) and @BindView (R2.id.xx) have tried, but still NullPointerException.Why is that？

My English is relatively poor, the above text from the Google translation, grammar unreasonable please understand

About this issue

Original URL
State: open
Created 7 years ago
Comments: 34 (1 by maintainers)

Most upvoted comments

must add annotationProcessor 'com.jakewharton:butterknife-compiler:8.8.1' in app module to solve this problem.

gmm932 on Dec 15, 2017

@qinxianyuzou 这个不是 bug ，因为 butterknife 的工作机制是：利用 annotationProcessor 来生成 XXX_ViewBinding 类的，对应的 XXX 里面的 View 的初始化是在 XXX_ViewBinding 内完成的。而 annotationProcessor 是以 module 为单位工作的，所以解决方法很简单，在 app module 内引用 annotationProcessor 而在 library 内引用 butterknife 即可解决。


  @Nullable @CheckResult @UiThread
  private static Constructor<? extends Unbinder> findBindingConstructorForClass(Class<?> cls) {
    Constructor<? extends Unbinder> bindingCtor = BINDINGS.get(cls);
    if (bindingCtor != null) {
      if (debug) Log.d(TAG, "HIT: Cached in binding map.");
      return bindingCtor;
    }
    String clsName = cls.getName();
    if (clsName.startsWith("android.") || clsName.startsWith("java.")) {
      if (debug) Log.d(TAG, "MISS: Reached framework class. Abandoning search.");
      return null;
    }
    try {
      Class<?> bindingClass = Class.forName(clsName + "_ViewBinding");
      //noinspection unchecked
      bindingCtor = (Constructor<? extends Unbinder>) bindingClass.getConstructor(cls, View.class);
      if (debug) Log.d(TAG, "HIT: Loaded binding class and constructor.");
    } catch (ClassNotFoundException e) {
      if (debug) Log.d(TAG, "Not found. Trying superclass " + cls.getSuperclass().getName());
      bindingCtor = findBindingConstructorForClass(cls.getSuperclass());
    } catch (NoSuchMethodException e) {
      throw new RuntimeException("Unable to find binding constructor for " + clsName, e);
    }
    BINDINGS.put(cls, bindingCtor);
    return bindingCtor;
  }

个人见解，轻喷

wangkunlin on Apr 19, 2018

@kassim Thank you kassim I just used “kapt” a minute ago and solved the problem. have a good day~!

BansookNam on Nov 8, 2017

Thank you @gmm932 Your suggestion works (probably missed that part from README file)

App level configuration:

dependencies {
    implementation 'com.jakewharton:butterknife:8.8.1'
    annotationProcessor 'com.jakewharton:butterknife-compiler:8.8.1'
}

Project level configuration:

buildscript {
     dependencies {
        classpath 'com.android.tools.build:gradle:3.0.1'
        classpath 'com.jakewharton:butterknife-gradle-plugin:8.8.1'
  }
}

om-ganesh on Apr 8, 2018

@qinxianyuzou 大神，问题解决没？我无意间看到其他大神在library里面引用butterknife，首先在project的gradle文件里面的buildscript下面用butterknife作者提供的插件dependencies { classpath ‘com.jakewharton:butterknife-gradle-plugin:8.8.1’ }，然后在library的module的gradle里面添加上这两个插件： apply plugin: ‘com.android.library’ apply plugin: ‘com.jakewharton.butterknife’ ，最后在所有@BindView的地方用R2.id.替换掉R.id.,这样就不会空指针了，好像butterknife的readme里面也是这样介绍的，可能大神你没太注意，希望可以帮助到你和其他遇到问题的大神们，好像说是android资源查找的机制导致的，所以jakewharton大神自己提供了一个gradle插件com.jakewharton:butterknife-gradle-plugin:***就是解决这个问题的

luckbing on Dec 12, 2017

did anyone find a solution? I am facing the same problem in gradle:3.0.0

nirmal912 on Nov 7, 2017

在defaultConfig中加入 javaCompileOptions { annotationProcessorOptions { includeCompileClasspath true } } 就可以继续用7.0.1啦，当前最新版本的问题还请 @JakeWharton 大神解决下

wangyuetingtao on Oct 31, 2017