jdk 8 lambda運算式 及在Android Studio的使用樣本

標籤：

以前覺得java讓人覺得有趣的一個特點是支援：匿名內部類，而最近發現jdk8已支援lambda並有更簡便的方式，來實現匿名內部類. 這會讓程式員更舒服，更喜歡java. 多年前覺得java文法和C#文法差得有點遠，沒有C#那麼寫來方便，現在覺得jdk8也很不錯了。做技術還是要向前看。

final TextView txtView2 = (TextView)this.findViewById(R.id.txtView2);Button btnChangeView = (Button)findViewById(R.id.btnChangeText);btnChangeView.setOnClickListener(new View.OnClickListener() {    @Override    public void onClick(View v) {        txtView2.setText("Text 改變");    }});

新的實現方式：

final TextView txtView2 = (TextView)this.findViewById(R.id.txtView2);Button btnChangeView = (Button)findViewById(R.id.btnChangeText);//btnChangeView.setOnClickListener(e -> Log.i("MyTag", "Button Clicked.") );assert btnChangeView != null;btnChangeView.setOnClickListener((view) -> {    Log.i(TAG, "btnChangeView Clicked:" + view.getId());    txtView2.setText("Text 改變:" + new Date().toString());});

 

參考：

http://stackoverflow.com/questions/37004069/errorjack-is-required-to-support-java-8-language-features

http://www.jianshu.com/p/5fc2b3362702

需要更改配置: build.gradle

defaultConfig {  ... jackOptions { enabled true    }  } compileOptions { sourceCompatibility JavaVersion.VERSION_1_8 targetCompatibility JavaVersion.VERSION_1_8 }

apply plugin: ‘com.android.application‘android {    compileSdkVersion 23    buildToolsVersion "24.0.2"    defaultConfig {        applicationId "com.firstapp.test.firstapp"        minSdkVersion 16        targetSdkVersion 23        versionCode 1        versionName "1.0"        jackOptions {            enabled true        }    }    buildTypes {        release {            minifyEnabled false            proguardFiles getDefaultProguardFile(‘proguard-android.txt‘), ‘proguard-rules.pro‘        }    }    compileOptions {        sourceCompatibility 1.8        targetCompatibility 1.8    }}dependencies {    compile fileTree(include: [‘*.jar‘], dir: ‘libs‘)    testCompile ‘junit:junit:4.12‘    compile ‘com.android.support:appcompat-v7:23.4.0‘}

 

jdk 8 lambda運算式 及在Android Studio的使用樣本