<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
            xmlns:tools="http://schemas.android.com/tools"
            android:layout_width="match_parent"
            android:layout_height="match_parent"
            android:paddingLeft="@dimen/activity_horizontal_margin"
            android:paddingRight="@dimen/activity_horizontal_margin"
            android:paddingTop="@dimen/activity_vertical_margin"
            android:paddingBottom="@dimen/activity_vertical_margin"
            tools:context=".MainActivity"
android:orientation="vertical">


    <EditText
    android:id="@+id/edittext"
    android:layout_width="match_parent"
    android:layout_height="wrap_content"/>

    <Button
    android:id="@+id/btn"
    android:layout_width="wrap_content"
    android:layout_height="wrap_content"
    android:text="insert image"/>

    <TextView
    android:id="@+id/text"
    android:layout_width="match_parent"
    android:layout_height="wrap_content"
    android:singleLine="true"
    android:ellipsize="end"/>
</LinearLayout>

public class MainActivity extends Activity {

private EditText editText;
private Button button;
private TextView textView;

private static final String PATTERN = "\[\w+?\]";
private Pattern pattern;

@Override
protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.activity_main);
    editText = (EditText) findViewById(R.id.edittext);
    button = (Button) findViewById(R.id.btn);
    textView = (TextView) findViewById(R.id.text);

    button.setOnClickListener(new View.OnClickListener() {
        @Override
        public void onClick(View v) {
            insertImageSpan();
        }
    });

    pattern = Pattern.compile(PATTERN);

    editText.setSpannableFactory(new Span());

    editText.addTextChangedListener(new TextWatcher() {
        @Override
        public void beforeTextChanged(CharSequence s, int start, int count, int after) {

        }

        @Override
        public void onTextChanged(CharSequence s, int start, int before, int count) {

        }

        @Override
        public void afterTextChanged(Editable s) {
            textView.setText(s);
        }
    });
}

private void insertImageSpan(){
    insertTextInCurrentPosition(editText,"[face]");
    int select = editText.getSelectionStart();
    editText.setText(spanText(editText.getText()));
    editText.setSelection(select);
}

public CharSequence spanText(CharSequence text) {
    SpannableStringBuilder t = null;
    if(text instanceof SpannableStringBuilder){
        t = (SpannableStringBuilder) text;
    }else{
        t = new SpannableStringBuilder(text);
    }
    Matcher m = pattern.matcher(text);
    while (m.find()) {
        String mResult = m.group();
        String key = mResult.substring(1, mResult.length() - 1);

        ImageSpan[] spans = t.getSpans(m.start(),m.end(),ImageSpan.class);
        if(spans== null || spans.length==0 ){
            try{
                ImageSpan span = new ImageSpan(this , R.drawable.ic_launcher);
                t.setSpan(span , m.start() , m.end() , Spannable.SPAN_EXCLUSIVE_EXCLUSIVE);
            }catch (Exception e){
                continue;
            }
        }

    }
    return t;
}

public static void insertTextInCurrentPosition(EditText tv, CharSequence str) {
    if (tv == null || TextUtils.isEmpty(str)) return;
    tv.getText().replace(tv.getSelectionStart() , tv.getSelectionEnd() , str , 0 , str.length());
}


@Override
public boolean onCreateOptionsMenu(Menu menu) {
    // Inflate the menu; this adds items to the action bar if it is present.
    getMenuInflater().inflate(R.menu.menu_main, menu);
    return true;
}

@Override
public boolean onOptionsItemSelected(MenuItem item) {
    // Handle action bar item clicks here. The action bar will
    // automatically handle clicks on the Home/Up button, so long
    // as you specify a parent activity in AndroidManifest.xml.
    int id = item.getItemId();

    //noinspection SimplifiableIfStatement
    if (id == R.id.action_settings) {
        return true;
    }

    return super.onOptionsItemSelected(item);
}

private class Span extends Spannable.Factory{
    @Override
    public Spannable newSpannable(CharSequence source) {
        source = spanText(source);
        SpannableString spannableString = new SpannableString(source);
        return spannableString;
    }
}
}