EditText输入内容即时捕捉----OnKeyListner事件
要想即时捕捉EditText中输入的内容，只要给EditText注册一个OnKeyListener（单击键盘事件处理）监听就可以了，在该监听事件里可以进行文字过滤。大部分widget都有setOnKeyListener方法没什么难点，只是在前面例子上稍作修改

package com.kevin.checkbox;import android.app.Activity;import android.os.Bundle;import android.text.method.HideReturnsTransformationMethod;import android.text.method.KeyListener;import android.text.method.PasswordTransformationMethod;import android.view.KeyEvent;import android.view.View;import android.view.View.OnKeyListener;import android.widget.CheckBox;import android.widget.CompoundButton;import android.widget.TextView;import android.widget.CompoundButton.OnCheckedChangeListener;import android.widget.EditText;public class Main extends Activity {private CheckBox chk_show;private EditText et_password;private TextView tv_result;    /** Called when the activity is first created. */    @Override    public void onCreate(Bundle savedInstanceState) {        super.onCreate(savedInstanceState);        setContentView(R.layout.main);        et_password = (EditText) findViewById(R.id.et_password);        chk_show = (CheckBox) findViewById(R.id.chk_show);        tv_result = (TextView) findViewById(R.id.tv_password);        chk_show.setOnCheckedChangeListener(new CheckChangedListener());        et_password.setOnKeyListener(new PasswordOnKeyListener());    }    // Checkbox的选择监听事件    class CheckChangedListener implements OnCheckedChangeListener{@Overridepublic void onCheckedChanged(CompoundButton buttonView,boolean isChecked) {if(isChecked){// 设置EditText的内容为显示et_password.setTransformationMethod(HideReturnsTransformationMethod.getInstance());}else{// 设置EditText的内容为隐藏et_password.setTransformationMethod(PasswordTransformationMethod.getInstance());}}        }    // EditText的键盘输入事件    class PasswordOnKeyListener implements OnKeyListener{@Overridepublic boolean onKey(View v, int keyCode, KeyEvent event) {EditText password = (EditText) v;// 在textview显示键盘输入值tv_result.setText(getString(R.string.result) + password.getText().toString());return false;}        }}