无法在滚动视图中查看任何内容（文本视图）

Question

I am unable to see anything (the textviews) after building the app. Only the background image is showing up and nothing else.Tried everything but still the texts doesn't show up. Under the scrollview i make a linear layout and under that there are several other textviews.But none of them are actually showing up when i am building the app. How can i make everything under the scrollview visible? Here's my code:

`

<ScrollView 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"
    android:background="@drawable/blck"
    android:weightSum="1"

    tools:context="com.gnulinuxusersgroup.nitdgp.glug.faqs"
    app:layout_collapseParallaxMultiplier="1.0">

    <!-- TODO: Update blank fragment layout -->

    <LinearLayout
        android:layout_width="match_parent"
        android:layout_height="match_parent"
        android:orientation="vertical">



    <TextView
            android:layout_width="match_parent"
            android:layout_height="75dp"
            android:id="@+id/F"
            tools:text="@string/faq"
            tools:textColor="#ffffff"
            tools:textSize="100px"

            android:textAppearance="@style/TextAppearance.AppCompat"
            android:layout_weight="0.02" />
        <TextView
            android:layout_width="match_parent"
            android:layout_height="130px"
            tools:text="@string/hwr"
            tools:textColor="#fff"
            tools:textSize="40px"
            tools:textStyle="bold"
            />

        <TextView
            android:layout_width="match_parent"
            android:layout_height="300px"
            tools:text="@##   `string/hwr2"
            tools:textColor="#fff"
            tools:textSize="40px"
            />

        <TextView
            android:layout_width="match_parent"
            android:layout_height="130px"
            tools:text="@string/foss"
            tools:textColor="#fff"
            tools:textSize="40px"
            tools:textStyle="bold"
            />

        <TextView
            android:layout_width="wrap_content"
            android:layout_height="269dp"
            tools:text="@string/foss2"
            tools:textColor="#fff"
            tools:textSize="40px" />
        <TextView
            android:layout_width="match_parent"
            android:layout_height="130px"
            tools:text="@string/work1"
            tools:textColor="#fff"
            tools:textSize="40px"
            tools:textStyle="bold"
            />
        <TextView
            android:layout_width="match_parent"
            android:layout_height="300px"
            tools:text="@string/work2"
            tools:textColor="#fff"
            tools:textSize="40px"
            />
        <TextView
            android:layout_width="match_parent"
            android:layout_height="130px"
            tools:text="@string/free"
            tools:textColor="#fff"
            tools:textSize="40px"
            tools:textStyle="bold"
            />
        <TextView
            android:layout_width="match_parent"
            android:layout_height="300px"
            tools:text="@string/free2"
            tools:textColor="#fff"
            tools:textSize="40px"
            />
        <TextView
            android:layout_width="match_parent"
            android:layout_height="46dp"
            tools:text="@string/git"
            tools:textColor="#fff"
            tools:textSize="40px"
            tools:textStyle="bold"
            />
        <TextView
            android:layout_width="match_parent"
            android:layout_height="300px"
            tools:text="@string/git2"
            tools:textColor="#fff"
            tools:textSize="40px"
            />
        <TextView
            android:layout_width="394dp"
            android:layout_height="50dp"
            tools:text="@string/gsoc"
            tools:textColor="#fff"
            tools:textSize="40px"
            tools:textStyle="bold"
            />
        <TextView
            android:layout_width="match_parent"
            android:layout_height="700px"
            tools:text="@string/gsoc2"
            tools:textColor="#fff"
            tools:textSize="40px"
            />
    </LinearLayout>
</ScrollView>

`

Answer 1

Replace your various tools: attributes with android: attributes.

The tools namespace is used only by the Android Studio design preview window. This allows you to do things like specify placeholder text so that you can see what it would look like... without specifyiing actual user-visible text that might incorrectly appear in the real world.

Take this TextView:

    <TextView
        android:layout_width="match_parent"
        android:layout_height="130px"
        tools:text="@string/hwr"
        tools:textColor="#fff"
        tools:textSize="40px"
        tools:textStyle="bold"
        />

Because all of the last four attributes use the tools namespace, they will not actually have any effect when you run the app. This is the same as having written this (as far as your running app is concerned):

    <TextView
        android:layout_width="match_parent"
        android:layout_height="130px"
        />

For now, just replace all the tools namespaces with android :

    <TextView
        android:layout_width="match_parent"
        android:layout_height="130px"
        android:text="@string/hwr"
        android:textColor="#fff"
        android:textSize="40px"
        android:textStyle="bold"
        />

Answer 2

Adding to the Ben P's answer, the possible culprits are:

1. Check your background color as you are setting text color to white make sure they have contrast.
2. As the orientation of LinearLayout is Vertical and you are using weight sum its better to have layout_height="0dp" in case of horizontal orientation have width as 0dp.
3. If you are specifying weightsum make sure the layout_weight adds up to the value, you can omit the weightsum by which system calculates percentages automatically by considering individual weights of widgets in group.

4. Also as the widgets are textview you can't see much difference in vertical orientation so i have changed the below xml orientation to horizontal so that while running on device or in the layout preview window you can see the weight difference clearly.

    <LinearLayout android:layout_width="match_parent" android:layout_height="match_parent" android:orientation="horizontal" > <TextView android:layout_width="wrap_content" android:layout_height="wrap_content" android:id="@+id/F" android:text="hello1" android:textSize="60px" android:textAppearance="@style/TextAppearance.AppCompat" android:layout_weight="1" /> <TextView android:layout_width="wrap_content" android:layout_height="wrap_content" android:text="hello1r" android:textSize="40px" android:textStyle="bold" android:layout_weight="4" /> <TextView android:layout_width="wrap_content" android:layout_height="wrap_content" android:text="hello3" android:layout_weight="1" android:textSize="40px" /> <TextView android:layout_width="wrap_content" android:layout_height="wrap_content" android:text="hello4" android:layout_weight="2" android:textSize="40px" android:textStyle="bold" /> <TextView android:layout_width="wrap_content" android:layout_height="wrap_content" android:layout_weight="2" android:text="hello5" android:textSize="40px" />