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使用 Kotlin 开发 Android 应用 | 8 个最优秀的 Android Studio 插件 Kotlin Android 素材

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butterknife

http://jakewharton.github.io/butterknife/

Annotate fields with @BindView and a view ID for Butter Knife to find and automatically cast the corresponding view in your layout.

class ExampleActivity extends Activity {
@BindView(R.id.title) TextView title;
@BindView(R.id.subtitle) TextView subtitle;
@BindView(R.id.footer) TextView footer;

@Override public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.simple_activity);
ButterKnife.bind(this);
// TODO Use fields…
}
}
Instead of slow reflection, code is generated to perform the view look-ups. Calling bind delegates to this generated code that you can see and debug.

The generated code for the above example is roughly equivalent to the following:

public void bind(ExampleActivity activity) {
activity.subtitle = (android.widget.TextView) activity.findViewById(2130968578);
activity.footer = (android.widget.TextView) activity.findViewById(2130968579);
activity.title = (android.widget.TextView) activity.findViewById(2130968577);
}
RESOURCE BINDING

Bind pre-defined resources with @BindBool, @BindColor, @BindDimen, @BindDrawable, @BindInt, @BindString, which binds an R.bool ID (or your specified type) to its corresponding field.

class ExampleActivity extends Activity {
@BindString(R.string.title) String title;
@BindDrawable(R.drawable.graphic) Drawable graphic;
@BindColor(R.color.red) int red; // int or ColorStateList field
@BindDimen(R.dimen.spacer) Float spacer; // int (for pixel size) or float (for exact value) field
// …
}
NON-ACTIVITY BINDING

You can also perform binding on arbitrary objects by supplying your own view root.

public class FancyFragment extends Fragment {
@BindView(R.id.button1) Button button1;
@BindView(R.id.button2) Button button2;

@Override public View onCreateView(LayoutInflater inflater, ViewGroup container, Bundle savedInstanceState) {
View view = inflater.inflate(R.layout.fancy_fragment, container, false);
ButterKnife.bind(this, view);
// TODO Use fields…
return view;
}
}
Another use is simplifying the view holder pattern inside of a list adapter.

public class MyAdapter extends BaseAdapter {
@Override public View getView(int position, View view, ViewGroup parent) {
ViewHolder holder;
if (view != null) {
holder = (ViewHolder) view.getTag();
} else {
view = inflater.inflate(R.layout.whatever, parent, false);
holder = new ViewHolder(view);
view.setTag(holder);
}

}

static class ViewHolder {
@BindView(R.id.title) TextView name;
@BindView(R.id.job_title) TextView jobTitle;

}
}
You can see this implementation in action in the provided sample.

Calls to ButterKnife.bind can be made anywhere you would otherwise put findViewById calls.

Other provided binding APIs:

Bind arbitrary objects using an activity as the view root. If you use a pattern like MVC you can bind the controller using its activity with ButterKnife.bind(this, activity).
Bind a view’s children into fields using ButterKnife.bind(this). If you use <merge> tags in a layout and inflate in a custom view constructor you can call this immediately after. Alternatively, custom view types inflated from XML can use it in the onFinishInflate() callback.
VIEW LISTS

You can group multiple views into a List or array.

@BindViews({ R.id.first_name, R.id.middle_name, R.id.last_name })
List<EditText> nameViews;
The apply method allows you to act on all the views in a list at once.

ButterKnife.apply(nameViews, DISABLE);
ButterKnife.apply(nameViews, ENABLED, false);
Action and Setter interfaces allow specifying simple behavior.

static final ButterKnife.Action<View> DISABLE = new ButterKnife.Action<View>() {
@Override public void apply(View view, int index) {
view.setEnabled(false);
}
};
static final ButterKnife.Setter<View, Boolean> ENABLED = new ButterKnife.Setter<View, Boolean>() {
@Override public void set(View view, Boolean value, int index) {
view.setEnabled(value);
}
};
An Android Property can also be used with the apply method.

ButterKnife.apply(nameViews, View.ALPHA, 0.0f);
LISTENER BINDING

Listeners can also automatically be configured onto methods.

@OnClick(R.id.submit)
public void submit(View view) {
// TODO submit data to server…
}
All arguments to the listener method are optional.

@OnClick(R.id.submit)
public void submit() {
// TODO submit data to server…
}
Define a specific type and it will automatically be cast.

@OnClick(R.id.submit)
public void sayHi(Button button) {
button.setText(“Hello!”);
}
Specify multiple IDs in a single binding for common event handling.

@OnClick({ R.id.door1, R.id.door2, R.id.door3 })
public void pickDoor(DoorView door) {
if (door.hasPrizeBehind()) {
Toast.makeText(this, “You win!”, LENGTH_SHORT).show();
} else {
Toast.makeText(this, “Try again”, LENGTH_SHORT).show();
}
}
Custom views can bind to their own listeners by not specifying an ID.

public class FancyButton extends Button {
@OnClick
public void onClick() {
// TODO do something!
}
}
BINDING RESET

Fragments have a different view lifecycle than activities. When binding a fragment in onCreateView, set the views to null in onDestroyView. Butter Knife returns an Unbinder instance when you call bind to do this for you. Call its unbind method in the appropriate lifecycle callback.

public class FancyFragment extends Fragment {
@BindView(R.id.button1) Button button1;
@BindView(R.id.button2) Button button2;
private Unbinder unbinder;

@Override public View onCreateView(LayoutInflater inflater, ViewGroup container, Bundle savedInstanceState) {
View view = inflater.inflate(R.layout.fancy_fragment, container, false);
unbinder = ButterKnife.bind(this, view);
// TODO Use fields…
return view;
}

@Override public void onDestroyView() {
super.onDestroyView();
unbinder.unbind();
}
}
OPTIONAL BINDINGS

By default, both @Bind and listener bindings are required. An exception will be thrown if the target view cannot be found.

To suppress this behavior and create an optional binding, add a @Nullable annotation to fields or the @Optional annotation to methods.

Note: Any annotation named @Nullable can be used for fields. It is encouraged to use the @Nullable annotation from Android’s “support-annotations” library.

@Nullable @BindView(R.id.might_not_be_there) TextView mightNotBeThere;

@Optional @OnClick(R.id.maybe_missing) void onMaybeMissingClicked() {
// TODO …
}
MULTI-METHOD LISTENERS

Method annotations whose corresponding listener has multiple callbacks can be used to bind to any one of them. Each annotation has a default callback that it binds to. Specify an alternate using the callback parameter.

@OnItemSelected(R.id.list_view)
void onItemSelected(int position) {
// TODO …
}

@OnItemSelected(value = R.id.maybe_missing, callback = NOTHING_SELECTED)
void onNothingSelected() {
// TODO …
}
BONUS

Also included are findById methods which simplify code that still has to find views on a View, Activity, or Dialog. It uses generics to infer the return type and automatically performs the cast.

View view = LayoutInflater.from(context).inflate(R.layout.thing, null);
TextView firstName = ButterKnife.findById(view, R.id.first_name);
TextView lastName = ButterKnife.findById(view, R.id.last_name);
ImageView photo = ButterKnife.findById(view, R.id.photo);
Add a static import for ButterKnife.findById and enjoy even more fun.

Download

GRADLE

compile ‘com.jakewharton:butterknife:(insert latest version)’
annotationProcessor ‘com.jakewharton:butterknife-compiler:(insert latest version)’
License

Copyright 2013 Jake Wharton

Licensed under the Apache License, Version 2.0 (the “License”);
you may not use this file except in compliance with the License.
You may obtain a copy of the License at

http://www.apache.org/licenses/LICENSE-2.0

Unless required by applicable law or agreed to in writing, software
distributed under the License is distributed on an “AS IS” BASIS,
WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
See the License for the specific language governing permissions and
limitations under the License.

8 个最优秀的 Android Studio 插件

    　　2、重启完Android Studio之后在任意一个包下右键New , 会发现多了一个”Kotlin File/Class” 和 “Kotlin Activity” 　　　　

    　　
    　　3、”Kotlin File/Class”即 Kotlin类或者文件
    　　　 “Kotlin Activity”即 Kotlin的Activity类
    　　
    　　4、试着建一个”Kotlin File/Class” 文件
    　　

    　　　　选择对所有modules配置还是对指定的配置
    　　　　选择OK后，会跳到build.gradle文件下，你会发现app下的build.gradle和根目录下的build.gradle文件都会出现变化
    　　　　注意黄色背景部分，没有的自己手动添加上去。

    　　　　根目录下的build.gradle:

    　　　　
    　　　　app目录下的build.gradle:

    接下来就可以进行Kotlin的编码实战了。
    浅谈Kotlin（一）：简介及Android Studio中配置
    浅谈Kotlin（二）：基本类型、基本语法、代码风格

    使用Kotlin&Anko, 扔掉XML开发Android应用

    尝鲜使用Kotlin写了一段时间Android。说大幅度的减少了Java代码一点不夸张。用Java的时候动不动就new一个OnClickListener()匿名类，动不动就类型转换的地方都可以省下很多。更不用说特殊的地方使用data class更是少些不知道多少代码。

    Jetbrains给Android带来的不仅是Kotlin，还有Anko。从Anko的官方说明来看这是一个雄心勃勃的要代替XML写Layout的新的开发方式。Anko最重要的一点是引入了DSL（Domain Specific Language）的方式开发Android界面布局。当然，本质是代码实现布局。不过使用Anko完全不用经历Java纯代码写Android的痛苦。因为本身是来自Kotlin的，所以自然的使用这种方式开发就具有了：

    类型安全，不再需要那么多的findById()之后的类型转换。
    null安全，Kotlin里，如果一个变量用示为可空，并且使用后再调用的时候，即使变量为空也不会引发异常。
    无需设备解析XML，因为Anko本质是代码实现的界面和布局，所以省去了这些麻烦。
    代码复用，可以通过继承AnkoComponent的方式实现代码复用。XML布局是每一个Activity，每一个View各自专属一个，
    代码复用比较少。
    来一个列子看一下。为了不太墨迹，一些不必要的xml声明此处略去。

    <RelativeLayout>

    </RelativeLayout>
    relativeLayout {
    val textView = textView(“Sample text view”) {
    textSize = 25f
    }.lparams {
    width = matchParent
    alignParentTop()
    }

    声明：本站部分文章及图片源自用户投稿，如本站任何资料有侵权请您尽早请联系jinwei@zod.com.cn进行处理,非常感谢！

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