Java 为什么我仍然能够使用support-v4库而不在gradle上导入它?
我很困惑,在我的gradle中,我没有导入support-v4,但我似乎能够使用库,support-v4是否默认作为依赖项包含?见下文?此外,在我的项目文件夹中,每次创建项目和各个模块时,我都可以看到jars支持v4 格拉德尔项目:Java 为什么我仍然能够使用support-v4库而不在gradle上导入它?,java,android,android-studio,gradle,support-v4,Java,Android,Android Studio,Gradle,Support V4,我很困惑,在我的gradle中,我没有导入support-v4,但我似乎能够使用库,support-v4是否默认作为依赖项包含?见下文?此外,在我的项目文件夹中,每次创建项目和各个模块时,我都可以看到jars支持v4 格拉德尔项目: // Top-level build file where you can add configuration options common to all sub-projects/modules. buildscript { repositories {
// 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:2.3.3'
// NOTE: Do not place your application dependencies here; they belong
// in the individual module build.gradle files
}
}
allprojects {
repositories {
jcenter()
maven{
url "https://maven.google.com"
}
}
}
task clean(type: Delete) {
delete rootProject.buildDir
}
我的应用程序gradle:
apply plugin: 'com.android.application'
android {
compileSdkVersion 26
buildToolsVersion "26.0.1"
defaultConfig {
applicationId "com.example.ok.applicationtest_v4lib"
minSdkVersion 19
targetSdkVersion 26
versionCode 1
versionName "1.0"
testInstrumentationRunner "android.support.test.runner.AndroidJUnitRunner"
}
buildTypes {
release {
minifyEnabled false
proguardFiles getDefaultProguardFile('proguard-android.txt'), 'proguard-rules.pro'
}
}
}
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-v7:26.0.1'
compile 'com.android.support.constraint:constraint-layout:1.0.2'
compile 'com.android.support:design:26.0.1'
testCompile 'junit:junit:4.12'
}
-下面的活动可以导入support-v4,而无需在gradle中导入support-v4:
package com.example.ok.applicationtest_v4lib;
import android.os.Bundle;
import android.support.design.widget.FloatingActionButton;
import android.support.design.widget.Snackbar;
import android.support.v4.app.ActivityCompat;
import android.support.v7.app.AppCompatActivity;
import android.support.v7.widget.Toolbar;
import android.view.View;
import android.view.Menu;
import android.view.MenuItem;
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();
}
});
//I am able to use below class yet I have not imported v4 library.
ActivityCompat
}
@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);
}
}
如果有
appcompat-v7
,则有appcompat-v4
运行/gradlew app:dependencies
,您将看到
+--- com.android.support:appcompat-v7:25.4.0
| +--- com.android.support:support-annotations:25.4.0
| +--- com.android.support:support-v4:25.4.0 (*)
| +--- com.android.support:support-vector-drawable:25.4.0
| | +--- com.android.support:support-annotations:25.4.0
| | \--- com.android.support:support-compat:25.4.0 (*)
| \--- com.android.support:animated-vector-drawable:25.4.0
| +--- com.android.support:support-vector-drawable:25.4.0 (*)
| \--- com.android.support:support-core-ui:25.4.0 (*)
而且
support:design
包括v7,所以即使有一个也不是必需的。所以,按照这种逻辑,如果我在我的gradle中包括依赖性支持设计,我不需要appcompat-v7或appcompat-v4,对吧?你不应该这样“优化”。如果您的代码需要某些库,请在gradle中设置适当的依赖项。其他库是否依赖于同一个库并不重要。实现依赖关系不是该库的任务。一个是它可能会停止依赖于该库,或者更喜欢其他版本,这会给您带来麻烦。而且你注定要失败-这很容易避免-只要管理自己的依赖关系就可以了如果我已经有了支持设计,那么删除support-v4和appcompat-v7是否安全?或者它们之间存在循环依赖?即使循环依赖。这不是一个问题,因为格拉德尔知道如何处理它。别管了。