我的项目：注意build.gradle文件：

// Top-level build file where you can add configuration options common to all sub-projects/modules.
buildscript {
    repositories {
        jcenter()
    }
    dependencies {
        classpath 'com.android.tools.build:gradle:1.2.3'

        // NOTE: Do not place your application dependencies here; they belong
        // in the individual module build.gradle files
    }
}

allprojects {
    repositories {
        jcenter()
    }
}

我的模块：app build.gradle文件：

apply plugin: 'com.android.application'

android {
    compileSdkVersion 22
    buildToolsVersion "22.0.1"

    defaultConfig {
        applicationId "com.example.noted"
        minSdkVersion 21
        targetSdkVersion 22
        versionCode 1
        versionName "1.0"
    }
    buildTypes {
        release {
            minifyEnabled false
            proguardFiles getDefaultProguardFile('proguard-android.txt'),'proguard-rules.pro'
        }
    }
}

dependencies {
    compile fileTree(dir: 'libs',include: ['*.jar'])
    compile 'com.android.support:appcompat-v7:22.2.0'
    compile 'com.android.support:support-v4:22.2.0'
    compile 'com.android.support:design:22.2.0'
}

在myactivity_main.xml中我尝试实现

<android.support.design.widget.FloatingActionButton 
    ... />

但是,在建立说明之后,我得到了一个“渲染问题”弹出窗口：

找不到以下类：
-android.support.design.widget.FloatingActionButton

我的猜测是,我的依赖关系出了问题,但我真的不知道.我一直试图让这个工作几个小时,没有运气,真的很感激任何帮助.

谢谢！