classpath "org.jetbrains.kotlin:kotlin-android-extensions:$kotlin_version"
Kotlin For Android 示例代码实战
// Top-level build file where you can add configuration options common to all sub-projects/modules. buildscript { ext.kotlin_version = '1.1.2-4' repositories { jcenter() } dependencies { classpath 'com.android.tools.build:gradle:2.3.0' classpath "org.jetbrains.kotlin:kotlin-gradle-plugin:$kotlin_version" classpath "org.jetbrains.kotlin:kotlin-android-extensions:$kotlin_version" // NOTE: Do not place your application dependencies here; they belong // in the individual module build.gradle files } } allprojects { repositories { jcenter() } } task clean(type: Delete) { delete rootProject.buildDir }
apply plugin: 'com.android.application' apply plugin: 'kotlin-android' apply plugin: 'kotlin-android-extensions' android { compileSdkVersion 25 buildToolsVersion "26.0.2" defaultConfig { applicationId "com.skex.kotlindemo" minSdkVersion 15 targetSdkVersion 25 versionCode 1 versionName "1.0" testInstrumentationRunner "android.support.test.runner.AndroidJUnitRunner" } buildTypes { release { minifyEnabled false proguardFiles getDefaultProguardFile('proguard-android.txt'), 'proguard-rules.pro' } } } dependencies { compile fileTree(dir: 'libs', include: ['*.jar']) androidTestCompile('com.android.support.test.espresso:espresso-core:2.2.2', { exclude group: 'com.android.support', module: 'support-annotations' }) compile 'com.android.support:appcompat-v7:25.3.1' compile 'com.android.support.constraint:constraint-layout:1.0.2' testCompile 'junit:junit:4.12' compile "org.jetbrains.kotlin:kotlin-stdlib-jre7:$kotlin_version" } repositories { mavenCentral() }
<?xml version="1.0" encoding="utf-8"?> <android.support.constraint.ConstraintLayout xmlns:android="http://schemas.android.com/apk/res/android" xmlns:app="http://schemas.android.com/apk/res-auto" xmlns:tools="http://schemas.android.com/tools" android:layout_width="match_parent" android:layout_height="match_parent" tools:context="com.skex.kotlindemo.MainActivity"> <TextView android:id="@+id/tv_text" android:layout_width="wrap_content" android:layout_height="wrap_content" android:text="Hello World!" app:layout_constraintBottom_toBottomOf="parent" app:layout_constraintLeft_toLeftOf="parent" app:layout_constraintRight_toRightOf="parent" app:layout_constraintTop_toTopOf="parent" /> </android.support.constraint.ConstraintLayout>
package com.skex.kotlindemo import android.support.v7.app.AppCompatActivity import android.os.Bundle import android.widget.TextView import kotlinx.android.synthetic.main.activity_main.* //import kotlinx.android.synthetic.activity_main.* class MainActivity : AppCompatActivity() { override fun onCreate(savedInstanceState: Bundle?) { super.onCreate(savedInstanceState) setContentView(R.layout.activity_main) //新添加的代码 //val textTv = findViewById(R.id.tv_text) as TextView //textTv.text = "Hello Kotlin! !" tv_text.text="Hello Kotlin! " } }
下面就为大家介绍怎么使用Kotlin来开发Android
上面这篇中我们在下载Kotlin插件的时候也下了一个功能扩张插件,其实这个插件大有用处,它可以使得我们在不使用注解和第三方库的情况下不使用findViewById来实例化控件,我们只需要导入对应的布局然后直接使用id来使用这个View就可以了。
扩展功能插件的使用
要使用这个功能:
1、首先需要导入这个插件的依赖,在Module的gradle中:
classpath "org.jetbrains.kotlin:kotlin-android-extensions:$kotlin_version"
- 1
2、建立一个layout布局,并给View定义一个id:
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:tools="http://schemas.android.com/tools"
android:layout_width="match_parent"
android:layout_height="match_parent"
android:paddingLeft="@dimen/activity_horizontal_margin"
android:paddingRight="@dimen/activity_horizontal_margin"
android:orientation="vertical"
tools:context=".MainActivity">
<TextView
android:id="@+id/textView"
android:layout_width="match_parent"
android:gravity="center"
android:layout_height="56dp"
android:textSize="16sp"/>
</LinearLayout>
3、导入布局,直接使用id来使用这个View:
在Activity中需要这样导入对应的layout
import kotlinx.android.synthetic.activity_main.*
然后就可以直接使用id来使用这个View了
textView.setText("Hello Kotlin")