Expandable/Collapsible TextView

activity_main.xml

<app.utils.customviews.SeeMoreTextView
    android:layout_height="wrap_content"
    android:layout_width="match_parent"
    app:ellipsizeColor="@color/grey"
    app:trimLength="120" />

attrs.xml

<resources>
    <declare-styleable name="SeeMoreTextView">
        <attr name="trimLength" format="integer"/>
        <attr name="ellipsizeColor" format="reference" />
    </declare-styleable>
</resources>

SeeMoreTextView.java

package app.utils.customviews;

import android.content.Context;
import android.content.res.TypedArray;
import android.graphics.Color;
import android.text.SpannableStringBuilder;
import android.text.Spanned;
import android.text.TextUtils;
import android.text.style.ForegroundColorSpan;
import android.util.AttributeSet;
import android.view.View;
import android.widget.TextView;

public class SeeMoreTextView extends TextView {
    private static final int DEFAULT_COLOR = Color.rgb(155, 155, 155);
    private static final int DEFAULT_TRIM_LENGTH = 130;
    private static final String ELLIPSIS = "... see more";

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

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

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

        TypedArray typedArray = context.obtainStyledAttributes(attrs, R.styleable.SeeMoreTextView);
        this.trimLength = typedArray.getInt(R.styleable.SeeMoreTextView_trimLength, DEFAULT_TRIM_LENGTH);
        this.seeMoreColor = typedArray.getColor(R.styleable.SeeMoreTextView_ellipsizeColor, DEFAULT_COLOR);
        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) {
            final ForegroundColorSpan colorSpan = new ForegroundColorSpan(seeMoreColor);
            SpannableStringBuilder seeMoreBuilder = new SpannableStringBuilder(ELLIPSIS);
            seeMoreBuilder.setSpan(colorSpan, 0, ELLIPSIS.length(), Spanned.SPAN_EXCLUSIVE_INCLUSIVE);
            SpannableStringBuilder trimmedBuilder = new SpannableStringBuilder(originalText, 0, trimLength + 1);
            return TextUtils.concat(trimmedBuilder, seeMoreBuilder);
        } 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;
    }
}