EditText输入密码时显示与隐藏

/**
 * 
 */
package com.test.sildingmenu;

import android.app.Activity;
import android.os.Bundle;
import android.text.TextUtils;
import android.text.method.HideReturnsTransformationMethod;
import android.text.method.PasswordTransformationMethod;
import android.view.View;
import android.view.View.OnClickListener;
import android.widget.Button;
import android.widget.EditText;

/**
 * @author wanggenping
 *
 */
public class PasswordActivity extends Activity{
    private EditText passwordEditText;
    private Button btn;
    
    private boolean isHidden = true;
    
    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_password);
        
        passwordEditText = (EditText) findViewById(R.id.activity_password_edittext);
        btn = (Button) findViewById(R.id.activity_password_btn);
        
        btn.setOnClickListener(new OnClickListener() {
            
            @Override
            public void onClick(View arg0) {
                if(! TextUtils.isEmpty(passwordEditText.getText().toString().trim())){
                    if(isHidden){
                        passwordEditText.setTransformationMethod(HideReturnsTransformationMethod.getInstance());
                    }else{
                        passwordEditText.setTransformationMethod(PasswordTransformationMethod.getInstance());
                    }
                    isHidden = !isHidden;
                    //切换后将EditText光标置于末尾
                    passwordEditText.setSelection(passwordEditText.getText().toString().trim().length());
                }
                
            }
        });
        
    }

}

activity_password.xml

<?xml version="1.0" encoding="utf-8"?>
<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:orientation="horizontal" >
    <EditText 
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:id="@+id/activity_password_edittext"
        android:inputType="textPassword"
        android:layout_alignParentLeft="true"
        android:layout_toLeftOf="@+id/activity_password_btn"/>
    <Button 
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:id="@+id/activity_password_btn"
        android:text="密码可见"
        android:layout_alignParentRight="true"/>
    

</RelativeLayout>