Category: Android

This Example responds to double <enter-key>s. In addition to the three Android classes used in the previous Example, it uses a MotionEvent.

EmptyEnter.java

import android.app.Activity;
import android.content.BroadcastReceiver;
import android.content.Context;
import android.content.Intent;
import android.content.IntentFilter;
import android.os.Bundle;
import android.support.v4.content.LocalBroadcastManager;
import android.text.Editable;
import android.text.TextWatcher;
import android.util.Log;
import android.view.inputmethod.EditorInfo;
import android.view.KeyEvent;
import android.view.MotionEvent;
import android.view.View;
import android.widget.EditText;

public class EmptyEnter extends Activity {
  EditText editText;
  boolean lastCharWasEnter;
  
  @Override
  public void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.main);
    editText=(EditText)findViewById(R.id.editText);
    lastCharWasEnter=false;
    
    editText.setOnTouchListener(new View.OnTouchListener() {
      @Override
      public boolean onTouch(View view, MotionEvent event) {
        lastCharWasEnter=false;
        return false;
      }
    });
    
    editText.addTextChangedListener(new TextWatcher() {
      public void beforeTextChanged
      (CharSequence s, int start, int count, int after) {
      }
      public void onTextChanged
      (CharSequence s, int start, int before, int count) {
        //check if exactly one char was entered and it was an 
        if (before==0 && count==1 && s.charAt(start)=='\n') {
          lastCharWasEnter=!lastCharWasEnter;
          if (lastCharWasEnter) return;
          Integer startInteger=new Integer(start);
          Intent intent=new Intent("enter");
          intent.putExtra("Start", startInteger.toString());
          mySendBroadcast(intent);
        }
        else lastCharWasEnter=false;
      }
      public void afterTextChanged(Editable s) {
      }
    });
  }

  private void mySendBroadcast(Intent intent) {
    //Can't instantiate LocalBroadcastMananager in Anonymous context
    LocalBroadcastManager.getInstance(this).sendBroadcast(intent);
  }
  
  @Override
  public void onResume() {
    super.onResume();
    // Register messageReceiver to receive messages.
    LocalBroadcastManager.getInstance(this).registerReceiver
    (startReceiver, new IntentFilter("enter"));
  }

  // handler for received Intents for the "enter" event 
  private BroadcastReceiver startReceiver = new BroadcastReceiver() {
    @Override
    public void onReceive(Context context, Intent intent) {
      // Extract data included in the Intent
      int start=Integer.parseInt(intent.getStringExtra("Start"));
      //replace the <enter>s
      editText.getText().replace(start-1, start+1,"");
      //respond to the double <enter-key>
      editText.getText().replace(start-1, start-1,"<>");
    }
  };
  
  @Override
  protected void onPause() {
    // Unregister since the activity is not visible
    LocalBroadcastManager.getInstance(this).unregisterReceiver(startReceiver);
    super.onPause();
  }
}

A dependable way to respond to the <enter-key> in an EditText is with a TextWatcher, a LocalBroadcastManager, and a BroadcastReceiver. I think you need to add the v4 support library to use the LocalBroadcastManager. I use the tutorial at vogella.com: 7.3 “Local broadcast events with LocalBroadcastManager” because of its complete concise code Example. In onTextChanged before is <the index of the end of the change before the change>minus start. When in the TextWatcher the UI thread is busy updating editText’s editable, so we send an Intent to wake up the BroadcastReceiver when the UI thread is done updating editText.

import android.content.Context;
import android.content.Intent;
import android.content.IntentFilter;
import android.text.Editable;
in onCreate:
editText.addTextChangedListener(new TextWatcher() {
  public void onTextChanged
  (CharSequence s, int start, int before, int count) {
    //check if exactly one char was added and it was an <enter>
    if (before==0 && count==1 && s.charAt(start)=='\n') {
    Intent intent=new Intent("enter")
    Integer startInteger=new Integer(start);
    intent.putExtra("Start", startInteger.toString()); // Add data
    mySendBroadcast(intent);
in the BroadcastReceiver's onReceive:
int start=Integer.parseInt(intent.getStringExtra("Start"));
editText.getText().replace(start, start+1,""); //remove the <enter>
//respond to the <enter> here

I took some time out to update the downloads in Android Questions, using the things I had learned while developing abicus, and I posted an excerpt from a comment on my blog’s EditText Enter Key post on stackoverflow.