Android--按钮点击事件

<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:orientation="vertical" >

    

    <EditText
        android:id="@+id/txtPassword"
        android:text=""
        android:layout_width="fill_parent"
        android:layout_height="70px"
        />

    <Button
        android:id="@+id/btnFirst"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:text="第一个" />

    <Button
        android:id="@+id/btnSecond"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:text="第二个" />
    
</LinearLayout>

package com.git.ch3;

import android.os.Bundle;
import android.app.Activity;
import android.app.AlertDialog;
import android.content.Context;
import android.content.DialogInterface;
import android.text.util.Linkify;
import android.view.Menu;
import android.view.MenuItem;
import android.view.View;
import android.view.View.OnClickListener;
import android.view.ViewGroup;
import android.widget.BaseAdapter;
import android.widget.Button;
import android.widget.EditText;
import android.widget.Gallery;
import android.widget.ImageView;
import android.widget.TextView;
import android.widget.Toast;

public class MainActivity extends Activity {

    private Button btnFirst=null;
    private Button btnSecond=null;
    private EditText lblTitle=null;
    
    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
        
        btnFirst=(Button)findViewById(R.id.btnFirst);
        btnSecond=(Button)findViewById(R.id.btnSecond);
        lblTitle=(EditText)findViewById(R.id.txtPassword);
        
        btnFirst.setOnClickListener(new Button.OnClickListener() {
            @Override
            public void onClick(View v) {
                String first= btnFirst.getText().toString();
                lblTitle.setText(first);
            }
        });
        
        btnSecond.setOnClickListener(new ButtonClick());
    }
    
    private class ButtonClick implements OnClickListener{

        @Override
        public void onClick(View v) {
            String first= btnSecond.getText().toString();
            lblTitle.setText(first);
        }
        
    }
}