ExpandableTextView.java

package tw.kaneshih.view;

import android.content.Context;
import android.support.annotation.DrawableRes;
import android.support.annotation.StringRes;
import android.util.AttributeSet;
import android.view.LayoutInflater;
import android.view.View;
import android.widget.ImageView;
import android.widget.LinearLayout;
import android.widget.TextView;

import tw.kaneshih.app.R;

public final class ExpandableTextView extends LinearLayout {
    private TextView content;
    private View button;
    private TextView buttonText;
    private ImageView buttonImage;

    private boolean isExpanded = false;

    private int collapsedLines = 2;
    private int drawableIdForExpand = R.drawable.ic_introduction_closed;
    private int drawableIdForCollapse = R.drawable.ic_introduction_open;
    private int stringIdForExpand = R.string.show_less;
    private int stringIdForCollapse = R.string.show_more;

    public ExpandableTextView(Context context) {
        super(context);
        initLayout(context);
    }

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

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

    private void initLayout(Context context) {
        LayoutInflater.from(context).inflate(R.layout.expandable_textview, this);
        content = (TextView) findViewById(R.id.expandable_textview_text);
        button = findViewById(R.id.expandable_textview_button);
        buttonText = (TextView) findViewById(R.id.expandable_textview_button_text);
        buttonImage = (ImageView) findViewById(R.id.expandable_textview_button_image);

        button.setOnClickListener(new OnClickListener() {
            @Override
            public void onClick(View v) {
                if (isExpanded) {
                    content.setMaxLines(collapsedLines);
                    buttonText.setText(stringIdForCollapse);
                    buttonImage.setImageResource(drawableIdForCollapse);
                } else {
                    content.setMaxLines(Integer.MAX_VALUE);
                    buttonText.setText(stringIdForExpand);
                    buttonImage.setImageResource(drawableIdForExpand);
                }
                isExpanded = !isExpanded;
                content.scrollTo(0, 0);
            }
        });
    }

    public void setText(String text) {
        content.setText(text);
    }

    /**
     * How many lines to show while this is collapsed?
     *
     * @param collapsedLines
     *            - default is 2
     */
    public void setCollapsedLines(int collapsedLines) {
        this.collapsedLines = collapsedLines;
    }

    public TextView getContentTextView() {
        return content;
    }

    /**
     * the arrow which at right side of button text
     *
     * @param forCollapse
     * @param forExpand
     */
    public void setResourceDrawableForButtonIndicator(@DrawableRes int forCollapse, @DrawableRes int forExpand) {
        this.drawableIdForCollapse = forCollapse;
        this.drawableIdForExpand = forExpand;
    }

    public void setResourceStringForButtonText(@StringRes int forCollapse, @StringRes int forExpand) {
        this.stringIdForCollapse = forCollapse;
        this.stringIdForExpand = forExpand;
    }

    public boolean isExpanded() {
        return isExpanded;
    }

}

/* XML R.layout.expandable_textview

<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
              android:layout_width="match_parent"
              android:layout_height="match_parent"
              android:orientation="vertical">

    <TextView
        android:id="@+id/expandable_textview_text"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:ellipsize="end"
        android:maxLines="2"
        android:textColor="@color/expandable_textview_text"
        android:textSize="@dimen/expandable_textview_textsize"
        android:textStyle="bold"/>

    <LinearLayout
        android:id="@+id/expandable_textview_button"
        android:layout_width="match_parent"
        android:layout_height="@dimen/expandable_textview_button_height"
        android:background="@drawable/bg_expandable_textview_button"
        android:clickable="true"
        android:gravity="center"
        android:orientation="horizontal">

        <TextView
            android:id="@+id/expandable_textview_button_text"
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"
            android:layout_marginRight="@dimen/expandable_textview_button_text_margin_right"
            android:text="@string/show_more"
            android:textColor="@color/expandable_textview_button_text"
            android:textSize="@dimen/expandable_textview_button_textsize"
            android:textStyle="bold"/>

        <ImageView
            android:id="@+id/expandable_textview_button_image"
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"
            android:src="@drawable/ic_introduction_open"/>
    </LinearLayout>
</LinearLayout>

*/