Android的 - 可扩展的TextView与动画(Android - Expandable Te

我有一个TextView这首先显示了长文本的一小部分。

用户可以按“看多”按钮，展开TextView ，看到文本的其余部分。

制作测试，我可以达到通过简单的交换价值TextView.setMaxLines的折叠和Integer.MAX_VALUE的扩大4之间。

现在，我想，这种行为将受动画陪同。 我知道，在这个问题的一个解决方案是差不多了，但我想实现它，我没有成功。

有人能帮助我吗？

提前致谢。

Answer 1:

你可以检查我的博客文章上ExpandableTexTView：

我们的想法是，最初的TextView将显示一个长文本的一小部分，被点击时，它会显示文本的其余部分。

因此，这里的代码，我如何解决它。

package com.rokonoid.widget;

import android.content.Context;
import android.content.res.TypedArray;
import android.text.SpannableStringBuilder;
import android.util.AttributeSet;
import android.view.View;
import android.widget.TextView;
/**
 * User: Bazlur Rahman Rokon
 * Date: 9/7/13 - 3:33 AM
 */
public class ExpandableTextView extends TextView {
    private static final int DEFAULT_TRIM_LENGTH = 200;
    private static final String ELLIPSIS = ".....";

    private CharSequence originalText;
    private CharSequence trimmedText;
    private BufferType bufferType;
    private boolean trim = true;
    private int trimLength;

    public ExpandableTextView(Context context) {
        this(context, null);
    }

    public ExpandableTextView(Context context, AttributeSet attrs) {
        super(context, attrs);

        TypedArray typedArray = context.obtainStyledAttributes(attrs, R.styleable.ExpandableTextView);
        this.trimLength = typedArray.getInt(R.styleable.ExpandableTextView_trimLength, DEFAULT_TRIM_LENGTH);
        typedArray.recycle();

        setOnClickListener(new OnClickListener() {
            @Override
            public void onClick(View v) {
                trim = !trim;
                setText();
                requestFocusFromTouch();
            }
        });
    }

    private void setText() {
        super.setText(getDisplayableText(), bufferType);
    }

    private CharSequence getDisplayableText() {
        return trim ? trimmedText : originalText;
    }

    @Override
    public void setText(CharSequence text, BufferType type) {
        originalText = text;
        trimmedText = getTrimmedText(text);
        bufferType = type;
        setText();
    }

    private CharSequence getTrimmedText(CharSequence text) {
        if (originalText != null && originalText.length() > trimLength) {
            return new SpannableStringBuilder(originalText, 0, trimLength + 1).append(ELLIPSIS);
        } else {
            return originalText;
        }
    }

    public CharSequence getOriginalText() {
        return originalText;
    }

    public void setTrimLength(int trimLength) {
        this.trimLength = trimLength;
        trimmedText = getTrimmedText(originalText);
        setText();
    }

    public int getTrimLength() {
        return trimLength;
    }
}

而在你attr.xml添加以下行

<?xml version="1.0" encoding="utf-8"?>
<resources>
<declare-styleable name="ExpandableTextView">
<attr name="trimLength" format="integer"/>
</declare-styleable>
</resources>

把下面的在你的main.xml

<?xml version="1.0" encoding="utf-8"?>
 <LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
 android:orientation="vertical"
 android:layout_width="fill_parent"
 android:layout_height="fill_parent"
 >
 <com.rokonoid.widget.ExpandableTextView
 android:id="@+id/lorem_ipsum"
 android:layout_width="fill_parent"
 android:layout_height="wrap_content"
 />
 </LinearLayout>

和测试活动

package com.rokonoid.widget;

import android.app.Activity;
import android.os.Bundle;

public class MyActivity extends Activity {

    @Override
    public void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.main);

        String yourText = "Lorem ipsum dolor sit amet, consectetur adipiscing elit. " +
                "Ut volutpat interdum interdum. Nulla laoreet lacus diam, vitae " +
                "sodales sapien commodo faucibus. Vestibulum et feugiat enim. Donec " +
                "semper mi et euismod tempor. Sed sodales eleifend mi id varius. Nam " +
                "et ornare enim, sit amet gravida sapien. Quisque gravida et enim vel " +
                "volutpat. Vivamus egestas ut felis a blandit. Vivamus fringilla " +
                "dignissim mollis. Maecenas imperdiet interdum hendrerit. Aliquam" +
                " dictum hendrerit ultrices. Ut vitae vestibulum dolor. Donec auctor ante" +
                " eget libero molestie porta. Nam tempor fringilla ultricies. Nam sem " +
                "lectus, feugiat eget ullamcorper vitae, ornare et sem. Fusce dapibus ipsum" +
                " sed laoreet suscipit. ";

        ExpandableTextView expandableTextView = (ExpandableTextView) findViewById(R.id.lorem_ipsum);
        expandableTextView.setText(yourText);

    }
}

参考： Android的-可扩展的TextView

Answer 2:

使用ObjectAnimator 。

ObjectAnimator animation = ObjectAnimator.ofInt(yourTextView, "maxLines", tv.getLineCount());
animation.setDuration(200).start();

这将充分扩展你的TextView超过200毫秒。 您可以更换tv.getLineCount()与文本然而，许多线路要崩溃了回去。

---- ----更新

下面是一些你可以顺路方便的方法：

private void expandTextView(TextView tv){
    ObjectAnimator animation = ObjectAnimator.ofInt(tv, "maxLines", tv.getLineCount());
    animation.setDuration(200).start();
}

private void collapseTextView(TextView tv, int numLines){
    ObjectAnimator animation = ObjectAnimator.ofInt(tv, "maxLines", numLines);
    animation.setDuration(200).start();
}

如果你在API 16+，您可以使用textView.getMaxLines（）可以轻松地确定您的TextView已经扩大与否。

private void cycleTextViewExpansion(TextView tv){
    int collapsedMaxLines = 3;
    ObjectAnimator animation = ObjectAnimator.ofInt(tv, "maxLines", 
        tv.getMaxLines() == collapsedMaxLines? tv.getLineCount() : collapsedMaxLines);
    animation.setDuration(200).start();
}

笔记：

如果MAXLINES尚未设置，或者你设置你的TextView的高度以像素为单位 ，你可以得到一个异常的ArrayIndexOutOfBounds。

以上的例子总是为200ms，如果你想扩展的符合率，你可以做这样的事情，他们是否通过3线或400扩展：

int duration = (textView.getLineCount() - collapsedMaxLines) * 10;

Answer 3:

我创建了一个开放源码库对于这一点，因为我是不满意的其他解决方案我在互联网上找到。 我已经把在GitHub上的东西，而且是免费的由任何人使用。

public class ExpandableTextView extends TextView
{
    // copy off TextView.LINES
    private static final int MAXMODE_LINES = 1;

    private OnExpandListener onExpandListener;
    private TimeInterpolator expandInterpolator;
    private TimeInterpolator collapseInterpolator;

    private final int maxLines;
    private long animationDuration;
    private boolean animating;
    private boolean expanded;
    private int originalHeight;

    public ExpandableTextView(final Context context)
    {
        this(context, null);
    }

    public ExpandableTextView(final Context context, final AttributeSet attrs)
    {
        this(context, attrs, 0);
    }

    public ExpandableTextView(final Context context, final AttributeSet attrs, final int defStyle)
    {
        super(context, attrs, defStyle);

        // read attributes
        final TypedArray attributes = context.obtainStyledAttributes(attrs, R.styleable.ExpandableTextView, defStyle, 0);
        this.animationDuration = attributes.getInt(R.styleable.ExpandableTextView_animation_duration, BuildConfig.DEFAULT_ANIMATION_DURATION);
        attributes.recycle();

        // keep the original value of maxLines
        this.maxLines = this.getMaxLines();

        // create default interpolators
        this.expandInterpolator = new AccelerateDecelerateInterpolator();
        this.collapseInterpolator = new AccelerateDecelerateInterpolator();
    }

    @Override
    public int getMaxLines()
    {
        if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.JELLY_BEAN)
        {
            return super.getMaxLines();
        }

        try
        {
            final Field mMaxMode = TextView.class.getField("mMaxMode");
            mMaxMode.setAccessible(true);
            final Field mMaximum = TextView.class.getField("mMaximum");
            mMaximum.setAccessible(true);

            final int mMaxModeValue = (int) mMaxMode.get(this);
            final int mMaximumValue = (int) mMaximum.get(this);

            return mMaxModeValue == MAXMODE_LINES ? mMaximumValue : -1;
        }
        catch (final Exception e)
        {
           return -1;
        }
    }

    /**
     * Toggle the expanded state of this {@link ExpandableTextView}.
     * @return true if toggled, false otherwise.
     */
    public boolean toggle()
    {
        if (this.expanded)
        {
            return this.collapse();
        }

        return this.expand();
    }

    /**
     * Expand this {@link ExpandableTextView}.
     * @return true if expanded, false otherwise.
     */
    public boolean expand()
    {
        if (!this.expanded && !this.animating && this.maxLines >= 0)
        {
            this.animating = true;

            // notify listener
            if (this.onExpandListener != null)
            {
                this.onExpandListener.onExpand(this);
            }

            // get original height
            this.measure
            (
                MeasureSpec.makeMeasureSpec(this.getMeasuredWidth(), MeasureSpec.EXACTLY),
                MeasureSpec.makeMeasureSpec(0, MeasureSpec.UNSPECIFIED)
            );

            this.originalHeight = this.getMeasuredHeight();

            // set maxLines to MAX Integer
            this.setMaxLines(Integer.MAX_VALUE);

            // get new height
            this.measure
            (
                MeasureSpec.makeMeasureSpec(this.getMeasuredWidth(), MeasureSpec.EXACTLY),
                MeasureSpec.makeMeasureSpec(0, MeasureSpec.UNSPECIFIED)
            );

            final int fullHeight = this.getMeasuredHeight();

            final ValueAnimator valueAnimator = ValueAnimator.ofInt(this.originalHeight, fullHeight);
            valueAnimator.addUpdateListener(new ValueAnimator.AnimatorUpdateListener()
            {
                @Override
                public void onAnimationUpdate(final ValueAnimator animation)
                {
                    final ViewGroup.LayoutParams layoutParams = ExpandableTextView.this.getLayoutParams();
                    layoutParams.height = (int) animation.getAnimatedValue();
                    ExpandableTextView.this.setLayoutParams(layoutParams);
                }
            });
            valueAnimator.addListener(new AnimatorListenerAdapter()
            {
                @Override
                public void onAnimationEnd(final Animator animation)
                {
                    ExpandableTextView.this.expanded = true;
                    ExpandableTextView.this.animating = false;
                }
            });

            // set interpolator
            valueAnimator.setInterpolator(this.expandInterpolator);

            // start the animation
            valueAnimator
                .setDuration(this.animationDuration)
                .start();

            return true;
        }

        return false;
    }

    /**
     * Collapse this {@link TextView}.
     * @return true if collapsed, false otherwise.
     */
    public boolean collapse()
    {
        if (this.expanded && !this.animating && this.maxLines >= 0)
        {
            this.animating = true;

            // notify listener
            if (this.onExpandListener != null)
            {
                this.onExpandListener.onCollapse(this);
            }

            // get new height
            final int fullHeight = this.getMeasuredHeight();

            final ValueAnimator valueAnimator = ValueAnimator.ofInt(fullHeight, this.originalHeight);
            valueAnimator.addUpdateListener(new ValueAnimator.AnimatorUpdateListener()
            {
                @Override
                public void onAnimationUpdate(final ValueAnimator animation)
                {
                    final ViewGroup.LayoutParams layoutParams = ExpandableTextView.this.getLayoutParams();
                    layoutParams.height = (int) animation.getAnimatedValue();
                    ExpandableTextView.this.setLayoutParams(layoutParams);
                }
            });
            valueAnimator.addListener(new AnimatorListenerAdapter()
            {
                @Override
                public void onAnimationEnd(final Animator animation)
                {
                    // set maxLines to original value
                    ExpandableTextView.this.setMaxLines(ExpandableTextView.this.maxLines);

                    ExpandableTextView.this.expanded = false;
                    ExpandableTextView.this.animating = false;
                }
            });

            // set interpolator
            valueAnimator.setInterpolator(this.collapseInterpolator);

            // start the animation
            valueAnimator
                .setDuration(this.animationDuration)
                .start();

            return true;
        }

        return false;
    }

    /**
     * Sets the duration of the expand / collapse animation.
     * @param animationDuration duration in milliseconds.
     */
    public void setAnimationDuration(final long animationDuration)
    {
        this.animationDuration = animationDuration;
    }

    /**
     * Sets a listener which receives updates about this {@link ExpandableTextView}.
     * @param onExpandListener the listener.
     */
    public void setOnExpandListener(final OnExpandListener onExpandListener)
    {
        this.onExpandListener = onExpandListener;
    }

    /**
     * Returns the {@link OnExpandListener}.
     * @return the listener.
     */
    public OnExpandListener getOnExpandListener()
    {
        return onExpandListener;
    }

    /**
     * Sets a {@link TimeInterpolator} for expanding and collapsing.
     * @param interpolator the interpolator
     */
    public void setInterpolator(final TimeInterpolator interpolator)
    {
        this.expandInterpolator = interpolator;
        this.collapseInterpolator = interpolator;
    }

    /**
     * Sets a {@link TimeInterpolator} for expanding.
     * @param expandInterpolator the interpolator
     */
    public void setExpandInterpolator(final TimeInterpolator expandInterpolator)
    {
        this.expandInterpolator = expandInterpolator;
    }

    /**
     * Returns the current {@link TimeInterpolator} for expanding.
     * @return the current interpolator, null by default.
     */
    public TimeInterpolator getExpandInterpolator()
    {
        return this.expandInterpolator;
    }

    /**
     * Sets a {@link TimeInterpolator} for collpasing.
     * @param collapseInterpolator the interpolator
     */
    public void setCollapseInterpolator(final TimeInterpolator collapseInterpolator)
    {
        this.collapseInterpolator = collapseInterpolator;
    }

    /**
     * Returns the current {@link TimeInterpolator} for collapsing.
     * @return the current interpolator, null by default.
     */
    public TimeInterpolator getCollapseInterpolator()
    {
        return this.collapseInterpolator;
    }

    /**
     * Is this {@link ExpandableTextView} expanded or not?
     * @return true if expanded, false if collapsed.
     */
    public boolean isExpanded()
    {
        return this.expanded;
    }

    public interface OnExpandListener
    {
        void onExpand(ExpandableTextView view);
        void onCollapse(ExpandableTextView view);
    }
}

使用ExpandableTextView是很容易的，它只是一个普通的TextView与添加到它的一些额外的功能。 通过定义的android：MAXLINES属性，你可以设置TextView的行数为缺省值折叠状态。

<LinearLayout
    xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:app="http://schemas.android.com/apk/res-auto"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:orientation="vertical">

    <at.blogc.android.views.ExpandableTextView
        android:id="@+id/expandableTextView"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:text="@string/lorem_ipsum"
        android:maxLines="5"
        android:ellipsize="end"
        app:animation_duration="1000"/>

    <!-- Optional parameter animation_duration: sets the duration of the expand animation -->

    <Button
        android:id="@+id/button_toggle"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:text="@string/expand"/>

</LinearLayout>

在您的活动或片段：

    final ExpandableTextView expandableTextView = (ExpandableTextView) this.findViewById(R.id.expandableTextView);
    final Button buttonToggle = (Button) this.findViewById(R.id.button_toggle);

    // set animation duration via code, but preferable in your layout files by using the animation_duration attribute
    expandableTextView.setAnimationDuration(1000L);

// set interpolators for both expanding and collapsing animations
expandableTextView.setInterpolator(new OvershootInterpolator());

// or set them separately
expandableTextView.setExpandInterpolator(new OvershootInterpolator());
expandableTextView.setCollapseInterpolator(new OvershootInterpolator());


    // toggle the ExpandableTextView
    buttonToggle.setOnClickListener(new View.OnClickListener()
    {
        @Override
        public void onClick(final View v)
        {
            expandableTextView.toggle();
            buttonToggle.setText(expandableTextView.isExpanded() ? R.string.collapse : R.string.expand);
        }
    });

    // but, you can also do the checks yourself
    buttonToggle.setOnClickListener(new View.OnClickListener()
    {
        @Override
        public void onClick(final View v)
        {
            if (expandableTextView.isExpanded())
            {
                expandableTextView.collapse();
                buttonToggle.setText(R.string.expand);
            }
            else
            {
                expandableTextView.expand();
                buttonToggle.setText(R.string.collapse);
            }
        }
    });

    // listen for expand / collapse events
    expandableTextView.setOnExpandListener(new ExpandableTextView.OnExpandListener()
    {
        @Override
        public void onExpand(final ExpandableTextView view)
        {
            Log.d(TAG, "ExpandableTextView expanded");
        }

        @Override
        public void onCollapse(final ExpandableTextView view)
        {
            Log.d(TAG, "ExpandableTextView collapsed");
        }
    });

您可以轻松地添加此库作为gradle这个依赖于你的Android项目。 看看在Github上项目作进一步的说明：

https://github.com/Blogcat/Android-ExpandableTextView

Answer 4:

平滑扩展（使用HEIGH＆ ObjectAnimator ）
FYI：需要API 11

public static void expandCollapsedByMaxLines(@NonNull final TextView text) {
    final int height = text.getMeasuredHeight();
    text.setHeight(height);
    text.setMaxLines(Integer.MAX_VALUE); //expand fully
    text.measure(View.MeasureSpec.makeMeasureSpec(text.getMeasuredWidth(), View.MeasureSpec.EXACTLY), View.MeasureSpec.makeMeasureSpec(ViewGroup.LayoutParams.WRAP_CONTENT, View.MeasureSpec.UNSPECIFIED));
    final int newHeight = text.getMeasuredHeight();
    ObjectAnimator animation = ObjectAnimator.ofInt(text, "height", height, newHeight);
    animation.setDuration(250).start();
}

PS我假设的TextView通过MAXLINES限制。
PSS感谢Amagi82的ObjectAnimator例如

Answer 5:

如果您想根据行数去做，这里有一个办法做到这一点：

（ 要点的全码）

/**
 * Ellipsize the text when the lines of text exceeds the value provided by {@link #makeExpandable} methods.
 * Appends {@link #MORE} or {@link #LESS} as needed.
 * TODO: add animation
 * Created by vedant on 3/10/15.
 */
public class ExpandableTextView extends TextView {
    private static final String TAG = "ExpandableTextView";
    private static final String ELLIPSIZE = "... ";
    private static final String MORE = "more";
    private static final String LESS = "less";

    private String mFullText;
    private int mMaxLines;

    //...constructors...

    public void makeExpandable(String fullText, int maxLines) {
        mFullText =fullText;
        mMaxLines = maxLines;
        ViewTreeObserver vto = getViewTreeObserver();
        vto.addOnGlobalLayoutListener(new ViewTreeObserver.OnGlobalLayoutListener() {
            @Override
            public void onGlobalLayout() {
                ViewTreeObserver obs = getViewTreeObserver();
                obs.removeOnGlobalLayoutListener(this);
                if (getLineCount() <= maxLines) {
                    setText(mFullText);
                } else {
                    setMovementMethod(LinkMovementMethod.getInstance());
                    showLess();
                }
            }
        });
    }

    /**
     * truncate text and append a clickable {@link #MORE}
     */
    private void showLess() {
        int lineEndIndex = getLayout().getLineEnd(mMaxLines - 1);
        String newText = mFullText.substring(0, lineEndIndex - (ELLIPSIZE.length() + MORE.length() + 1))
                + ELLIPSIZE + MORE;
        SpannableStringBuilder builder = new SpannableStringBuilder(newText);
        builder.setSpan(new ClickableSpan() {
            @Override
            public void onClick(View widget) {
                showMore();
            }
        }, newText.length() - MORE.length(), newText.length(), 0);
        setText(builder, BufferType.SPANNABLE);
    }

    /**
     * show full text and append a clickable {@link #LESS}
     */
    private void showMore() {
        // create a text like subText + ELLIPSIZE + MORE
        SpannableStringBuilder builder = new SpannableStringBuilder(mFullText + LESS);
        builder.setSpan(new ClickableSpan() {
            @Override
            public void onClick(View widget) {
                showLess();
            }
        }, builder.length() - LESS.length(), builder.length(), 0);
        setText(builder, BufferType.SPANNABLE);
    }
}

Answer 6:

下面是使用上面的一些反应（我用的例子ButterKnife）什么工作对我来说：

private static final MAX_LINE_COUNT = 3;    

@Bind(R.id.description)
TextView mDescription;    

@Override
protected void onCreate(Bundle savedInstanceState) {

  if(!TextUtils.isEmpty(mDescription)) {
    mDescription.setText(mItem.description);
    mDescription.setMaxLines(MAX_LINE_COUNT);
    mDescription.setEllipsize(TextUtils.TruncateAt.END);
  } else {
    mDescription.setVisibility(View.GONE);
  }

}

@OnClick(R.id.description)
void collapseExpandTextView(TextView tv) {

    if (tv.getMaxLines() == MAX_LINE_COUNT) {
        // collapsed - expand it
        tv.setEllipsize(null);
        tv.setMaxLines(Integer.MAX_VALUE);
    } else {
        // expanded - collapse it
        tv.setEllipsize(TextUtils.TruncateAt.END);
        tv.setMaxLines(MAX_LINE_COUNT);
    }

    ObjectAnimator animation = ObjectAnimator.ofInt(tv, "maxLines", tv.getMaxLines());
    animation.setDuration(200).start();
}   

当用户点击说明它要么折叠或展开基于最大线。 这将仅适用于API 16+工作。

我跑进问题是线数在点，线数和最大计数返回零是在某些点的值相同。

Answer 7:

请参阅下面的选项链接，可扩展的TextView的行数和更少的文字。

可调整大小的文本视图（查看更多和查看更少）

添加下面的Java类线在你的TextView设置文本之后。

// YourCustomeClass.class [your customized class]
// yourTextView [ TextView yourTextView = findViewById(R.id.yourTextView) ];

YourCustomeClass.doResizeTextView(yourTextView, 3, "More", true);

// 3 - No of lines after user wants to expand it. 
// "More" : text want to see end of your TextView after shrink
// True : flag for viewMore

Answer 8:

你可以做这样的事情。 它会在任何一种观点工作，无论是普通视图，或内部的ListView或RecyclerView一个观点：

在onCreate()或类似的东西，添加：

// initialize integers
int collapsedHeight, expandedHeight;

// get collapsed height after TextView is drawn
textView.post(new Runnable() {
    @Override
    public void run() {
        collapsedHeight = textView.getMeasuredHeight();
    }
});

// view that will expand/collapse your TextView
view.setOnClickListener(new View.OnClickListener() {
    @Override
    public void onClick(View view) {
        // number of max lines when collapsed
        if (textView.getMaxLines() == 2) {
            // expand
            textView.setMaxLines(Integer.MAX_VALUE);
            textView.measure(View.MeasureSpec.makeMeasureSpec(notifMessage.getMeasuredWidth(), View.MeasureSpec.EXACTLY), View.MeasureSpec.makeMeasureSpec(View.MeasureSpec.UNSPECIFIED, View.MeasureSpec.UNSPECIFIED));
            expandedHeight = textView.getMeasuredHeight();
            ObjectAnimator animation = ObjectAnimator.ofInt(textView, "height", collapsedHeight, expandedHeight);
            animation.setDuration(250).start();
        } else {
            // collapse
            ObjectAnimator animation = ObjectAnimator.ofInt(textView, "height", expandedHeight, collapsedHeight);
            animation.addListener(new Animator.AnimatorListener() {
                @Override
                public void onAnimationStart(Animator animator) {

                }

                @Override
                public void onAnimationEnd(Animator animator) {
                    // number of max lines when collapsed
                    textView.setMaxLines(2);
                }

                @Override
                public void onAnimationCancel(Animator animator) {

                }

                @Override
                public void onAnimationRepeat(Animator animator) {

                }
            });
            animation.setDuration(250).start();
        }
    }
});

这将让你展开/点击你想要的任何观点崩溃一个TextView。 （你一定能选择的TextView本身太）

Answer 9:

在ListView控件或RecyclerView，而不是使用OnGlobalLayoutListener我们总是用OnPreDrawListener。 此回调也烧在开始不可见的行。 从官方文档：

private void makeTextViewResizable(final TextView tv, final int maxLine, final String expandText, final boolean viewMore){
        try {
            if (tv.getTag() == null) {
                tv.setTag(tv.getText());
            }
            //OnGlobalLayoutListener
            ViewTreeObserver vto = tv.getViewTreeObserver();
            vto.addOnPreDrawListener(new ViewTreeObserver.OnPreDrawListener() {

                @Override
                public boolean onPreDraw() {

                        ViewTreeObserver obs = tv.getViewTreeObserver();
                       // obs.removeGlobalOnLayoutListener((ViewTreeObserver.OnGlobalLayoutListener) mActivity);
                        obs.removeOnPreDrawListener(this);
                        if (maxLine == 0) {
                            int lineEndIndex = tv.getLayout().getLineEnd(0);
                            String text = tv.getText().subSequence(0, lineEndIndex - expandText.length() + 1) + " " + expandText;
                            tv.setText(text);
                            tv.setMovementMethod(LinkMovementMethod.getInstance());
                            tv.setText(
                                    addClickablePartTextViewResizable(Html.fromHtml(tv.getText().toString()), tv, expandText,
                                            viewMore), TextView.BufferType.SPANNABLE);
                        } else if (maxLine > 0 && tv.getLineCount() >= maxLine) {
                            int lineEndIndex = tv.getLayout().getLineEnd(maxLine - 1);
                            String text = tv.getText().subSequence(0, lineEndIndex - expandText.length() + 1) + " " + expandText;
                            tv.setText(text);
                            tv.setMovementMethod(LinkMovementMethod.getInstance());
                            tv.setText(
                                    addClickablePartTextViewResizable(Html.fromHtml(tv.getText().toString()), tv, expandText,
                                            viewMore), TextView.BufferType.SPANNABLE);
                        } else {
                            int lineEndIndex = tv.getLayout().getLineEnd(tv.getLayout().getLineCount() - 1);
                            String text = tv.getText().subSequence(0, lineEndIndex) + " " + expandText;
                            tv.setText(text);
                            tv.setMovementMethod(LinkMovementMethod.getInstance());
                            tv.setText(
                                    addClickablePartTextViewResizable(Html.fromHtml(tv.getText().toString()), tv, expandText,
                                            viewMore), TextView.BufferType.SPANNABLE);
                        }


                    return true;
                }


            });
        } catch (Exception e) {
            e.printStackTrace();
        }

    }

Answer 10:

主要用于添加“查看更多”的文本结束的情况下，我向你们介绍我的TruncatingTextView。 多次实验后似乎加载在RecyclerView项目视图，这些文本视图时无缝工作。

package com.example.android.widgets;

import android.content.Context;
import android.support.annotation.Nullable;
import android.support.v7.widget.AppCompatTextView;
import android.text.Spannable;
import android.text.SpannableString;
import android.text.TextUtils;
import android.text.style.ForegroundColorSpan;
import android.text.style.RelativeSizeSpan;
import android.util.AttributeSet;

import com.example.android.R;

public class TruncatingTextView extends AppCompatTextView {
    public static final String TWO_SPACES = "  ";

    private int truncateAfter = Integer.MAX_VALUE;

    private String suffix;
    private RelativeSizeSpan truncateTextSpan = new RelativeSizeSpan(0.75f);
    private ForegroundColorSpan viewMoreTextSpan = new ForegroundColorSpan(Color.BLUE);
    private static final String MORE_STRING = getContext().getString(R.string.more);

    private static final String ELLIPSIS = getContext().getString(R.string.ellipsis);

    public TruncatingTextView(Context context) {
        super(context);
    }

    public TruncatingTextView(Context context, AttributeSet attrs) {
        super(context, attrs);
    }

    public TruncatingTextView(Context context, AttributeSet attrs, int defStyleAttr) {
        super(context, attrs, defStyleAttr);
    }

    public void setText(CharSequence fullText, @Nullable CharSequence afterTruncation, int truncateAfterLineCount) {
        this.suffix = TWO_SPACES + MORE_STRING;

        if (!TextUtils.isEmpty(afterTruncation)) {
            suffix += TWO_SPACES + afterTruncation;
        }

        // Don't call setMaxLines() unless we have to, since it does a redraw.
        if (this.truncateAfter != truncateAfterLineCount) {
            this.truncateAfter = truncateAfterLineCount;
            setMaxLines(truncateAfter);
        }

        setText(fullText);
    }

    @Override
    protected void onLayout(boolean changed, int left, int top, int right, int bottom) {
        super.onLayout(changed, left, top, right, bottom);

        if (getLayout() != null && getLayout().getLineCount() > truncateAfter) {
            int lastCharToShowOfFullTextAfterTruncation = getLayout().getLineVisibleEnd(truncateAfter - 1) - suffix.length() - ELLIPSIS.length();

            if (getText().length() <= lastCharToShowOfFullTextAfterTruncation) {
                // No idea why this would be the case, but to prevent a crash, here it is. Besides, if this is true, we should be less than our maximum lines and thus good to go.
                return;
            }

            int startIndexOfMoreString = lastCharToShowOfFullTextAfterTruncation + TWO_SPACES.length() + 1;

            SpannableString truncatedSpannableString = new SpannableString(getText().subSequence(0, lastCharToShowOfFullTextAfterTruncation) + ELLIPSIS + suffix);
            truncatedSpannableString.setSpan(truncateTextSpan, startIndexOfMoreString, truncatedSpannableString.length(), Spannable.SPAN_EXCLUSIVE_INCLUSIVE);
            truncatedSpannableString.setSpan(viewMoreTextSpan, startIndexOfMoreString, startIndexOfMoreString + MORE_STRING.length(), Spannable.SPAN_EXCLUSIVE_EXCLUSIVE);
            setText(truncatedSpannableString);
        }
    }
}

您可以随时选择添加自己的属性为truncateAfter，并使用上述任何答案添加动画展开/折叠（我没有代码来处理展开/折叠，但通过使用上述动画的一个答案很容易做到）。

我在这里更将这种为别人谁正在努力寻找他们的文本意见“查看更多”功能。

Answer 11:

现在，它更容易为用户提供动画和使用这个真棒库所需的所有控制要求的TextView ExpandableTextView ，在这个库，你只有将其添加到您的gradle这个，然后定义它像在你的XML如下：

  <com.ms.square.android.expandabletextview.ExpandableTextView
      xmlns:android="http://schemas.android.com/apk/res/android"
      xmlns:expandableTextView="http://schemas.android.com/apk/res-auto"
      android:id="@+id/expand_text_view"
      android:layout_width="match_parent"
      android:layout_height="wrap_content"
      expandableTextView:maxCollapsedLines="4"
      expandableTextView:animDuration="200">
      <TextView
          android:id="@id/expandable_text"
          android:layout_width="match_parent"
          android:layout_height="wrap_content"
          android:layout_marginLeft="10dp"
          android:layout_marginRight="10dp"
          android:textSize="16sp"
          android:textColor="#666666" />
      <ImageButton
          android:id="@id/expand_collapse"
          android:layout_width="wrap_content"
          android:layout_height="wrap_content"
          android:padding="16dp"
          android:layout_gravity="right|bottom"
          android:background="@android:color/transparent"/>
  </com.ms.square.android.expandabletextview.ExpandableTextView>

之后使用它在你的代码，如：

TextView expandableTextView = (ExpandableTextView) findViewById(R.id.expand_text_view);

正如你看到的，你可以控制你的TextView你想要的最大线和动画持续时间和所有必要的设置扩展技术。

Answer 12:

下面是一个类似的方法回购： https://github.com/CorradiSebastian/ExpandableTextView

从这个问题就出来了：

自定义扩展的TextView

文章来源: Android - Expandable TextView with Animation