<LinearLayout
        android:layout_width="match_parent"
        android:orientation="horizontal"
        android:layout_height="wrap_content">
        <TextView
            android:id="@+id/expandableTextView"
            android:layout_width="0dp"
            android:layout_height="wrap_content"
            android:layout_weight="1"/>
        <ImageButton
            android:id="@+id/expandBtn"
            android:src="@drawable/plusIcon"
            android:layout_width="wrap_content"
            android:layout_height="wrap_content" />
        </LinearLayout>

final int MIN_CHARS = 10;
    String fullText;
    boolean isExpanded;

    TextView textView = (TextView) findViewById(R.id.expandableTextView);
    ImageButton imageButton = (ImageButton) findViewById(R.id.expandBtn);

    fullText = textView.getText().toString();
    textView.setText(fullText.substring(0,MIN_CHARS));
    imageButton.setImageResource(R.drawable.plusIcon);
    imageButton.setOnClickListener(new View.OnClickListener() {
        @Override
        public void onClick(View v) {
            isExpanded = ! isExpanded;
            imageButton.setImageResource(isExpanded?R.drawable.minusIcon:R.drawable.plusIcon);
            textView.setText(isExpanded?fullText:fullText.substring(0,MIN_CHARS));
        }
    });