TextView that automatically adjusts it's size to fit the container.

FontFitTextView.java

/**
 * @author fernandohur but credit goes to <a href="http://stackoverflow.com/questions/2617266/how-to-adjust-text-font-size-to-fit-textview">speedplane</a>
 */
public class FontFitTextView extends TextView {

    private Paint mTestPaint;
    /**
     * The minimum font size in pixels
     */
    private float minFontSize;

    public FontFitTextView(Context context) {
        super(context);
        initialise();
    }

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

    /**
     * Sets the minimum allowed font size
     * @param fontSizeDp the font size in dp
     */
    public void setMinFontSize(int fontSizeDp){
        minFontSize = UIHelper.getPixelsFromDp(getContext().getResources(), fontSizeDp);
    }

    private void initialise() {
        mTestPaint = new Paint();
        mTestPaint.set(this.getPaint());
        //max size defaults to the initially specified text size unless it is too small
        minFontSize = 0;
    }

    /* Re size the font so the specified text fits in the text box
     * assuming the text box is the specified width.
     */
    private void refitText(String text, int textWidth, int parentHeight) {
        if (textWidth <= 0)
            return;
        int targetWidth = textWidth - this.getPaddingLeft() - this.getPaddingRight();
        float hi = 100;
        float lo = 2;
        final float threshold = 0.5f; // How close we have to be

        mTestPaint.set(this.getPaint());

        while ((hi - lo) > threshold) {
            float size = (hi + lo) / 2;
            mTestPaint.setTextSize(size);
            if (mTestPaint.measureText(text) >= targetWidth)
                hi = size; // too big
            else
                lo = size; // too small
        }
        // Use lo so that we undershoot rather than overshoot
        Resources r = getResources();
        float px = TypedValue.applyDimension(TypedValue.COMPLEX_UNIT_DIP, 16, r.getDisplayMetrics());
        this.setTextSize(TypedValue.COMPLEX_UNIT_PX, Math.max(Math.min(lo, px), minFontSize));
    }

    @Override
    protected void onMeasure(int widthMeasureSpec, int heightMeasureSpec) {
        super.onMeasure(widthMeasureSpec, heightMeasureSpec);
        int parentWidth = MeasureSpec.getSize(widthMeasureSpec);
        int parentHeight = MeasureSpec.getSize(heightMeasureSpec);
        int height = getMeasuredHeight();
        refitText(this.getText().toString(), parentWidth, parentHeight);
        this.setMeasuredDimension(parentWidth, height);
    }

    @Override
    protected void onTextChanged(final CharSequence text, final int start, final int before, final int after) {
        refitText(text.toString(), this.getWidth(), this.getHeight());
    }

    @Override
    protected void onSizeChanged(int w, int h, int oldw, int oldh) {
        if (w != oldw) {
            refitText(this.getText().toString(), w, h);
        }
    }
}

This is a simple class that automatically changes the font's size to better fit the container.

It auto adjusts the TextView's font size to the parent's dimensions. You can also specify a minimum font size by calling setMinFontSize(int)

The UIHelper method is just this

public static float getPixelsFromDp(Resources resources, int dp) {
    return TypedValue.applyDimension(TypedValue.COMPLEX_UNIT_DIP, dp, resources.getDisplayMetrics());
}