1、啟動(dòng)白屏、黑屏

給啟動(dòng)頁設(shè)置Theme，看起來就像秒啟動(dòng)了。

<style name="SplashTheme" parent="Theme.AppCompat.NoActionBar">
        <item name="android:windowFullscreen">true</item>
        <item name="android:windowBackground">@mipmap/splash</item>
</style>

一般啟動(dòng)頁也就一張圖片，直接設(shè)置了android:windowBackground就可以，imageview都不用了。

Paste_Image.png

Paste_Image.png

2、ViewStub

A ViewStub is an invisible, zero-sized View that can be used to lazily inflate layout resources at runtime.
比如加載列表空布局、引導(dǎo)提示等。

<?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.wangsz.myapplication.MainActivity">

    <TextView
        android:id="@+id/textview"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:text="Toggle"
        app:layout_constraintBottom_toBottomOf="parent"
        app:layout_constraintLeft_toLeftOf="parent"
        app:layout_constraintRight_toRightOf="parent"/>

    <ViewStub
        android:id="@+id/viewstub"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:inflatedId="@+id/viewstub_layout"
        android:layout="@layout/viewstub_layout" />

</android.support.constraint.ConstraintLayout>

android:layout="@layout/viewstub_layout" ---ViewStub本身被替換掉的布局文件，調(diào)用viewStub.inflate()。
android:inflatedId="@+id/viewstub_layout" ---ViewStub被提替換之后的布局的id
替換之后的布局的長(zhǎng)寬還是以viewstub的屬性為準(zhǔn)：
android:layout_width="wrap_content"
android:layout_height="wrap_content"

• viewstub本身的setVisibility方法，在調(diào)用的時(shí)候會(huì)判斷是否inflate()，如果是第一次，則會(huì)設(shè)置viewstub本身的visibility，并且調(diào)用inflate()，當(dāng)再次調(diào)用setVisibility方法的時(shí)候，只會(huì)設(shè)置替換之后的view的visibility，所以viewstub的getVisibility()只會(huì)等于第一次設(shè)置之后的visibility。

/**
     * When visibility is set to {@link #VISIBLE} or {@link #INVISIBLE},
     * {@link #inflate()} is invoked and this StubbedView is replaced in its parent
     * by the inflated layout resource. After that calls to this function are passed
     * through to the inflated view.
     *
     * @param visibility One of {@link #VISIBLE}, {@link #INVISIBLE}, or {@link #GONE}.
     *
     * @see #inflate() 
     */
    @Override
    @android.view.RemotableViewMethod
    public void setVisibility(int visibility) {
        if (mInflatedViewRef != null) {
            View view = mInflatedViewRef.get();
            if (view != null) {
                view.setVisibility(visibility);
            } else {
                throw new IllegalStateException("setVisibility called on un-referenced view");
            }
        } else {
            super.setVisibility(visibility);
            if (visibility == VISIBLE || visibility == INVISIBLE) {
                inflate();
            }
        }
    }

Paste_Image.png

這段代碼，viewStub指向的layout會(huì)在第一次點(diǎn)擊textView的時(shí)候顯示，然后之后的所有點(diǎn)擊都是消失，因?yàn)橐婚_始viewStub.getVisibility() == View.GONE，第一次調(diào)用的viewStub.setVisibility(View.VISIBLE);之后viewStub.getVisibility()的值就一直等于View.VISIBLE，調(diào)用viewStub.setVisibility(View.INVISIBLE)只會(huì)控制指向的layout的顯示，不會(huì)改變viewStub的屬性。

• java.lang.IllegalStateException: ViewStub must have a non-null ViewGroup viewParent

對(duì)ViewStub的inflate操作只能進(jìn)行一次，因?yàn)閕nflate的時(shí)候是將其指向的布局文件解析inflate并替換掉當(dāng)前ViewStub本身（由此體現(xiàn)出了ViewStub“占位符”性質(zhì)），一旦替換后，此時(shí)原來的布局文件中就沒有ViewStub控件了，因此，如果多次對(duì)ViewStub進(jìn)行infalte，會(huì)出現(xiàn)錯(cuò)誤信息：ViewStub must have a non-null ViewGroup viewParent。
比如：

@Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);

        textView = (TextView) findViewById(R.id.textview);
        viewStub = (ViewStub) findViewById(R.id.viewstub);

        textView.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View v) {
                Log.i("viewStub",viewStub.getVisibility() + "");
                if (viewStub.getVisibility() == View.VISIBLE){
                    View view = viewStub.inflate();
                    viewStub.setVisibility(View.INVISIBLE);
                } else {
                    viewStub.setVisibility(View.VISIBLE);
                }
            }
        });

    }

第二次點(diǎn)擊textview就會(huì)報(bào)錯(cuò)，應(yīng)為第一次調(diào)用viewStub.setVisibility(View.VISIBLE)的時(shí)候已經(jīng)調(diào)用過一次inflate()。

3、AndroidStudio 便捷操作

Android Studio相見恨晚的操作錦集