谁能告诉我setEnable和setClickable的区别

 package com.example.progressdemo;

import java.util.Iterator;

import android.app.Activity;
import android.os.Bundle;
import android.os.Handler;
import android.view.Menu;
import android.view.MenuItem;
import android.view.View;
import android.view.View.OnClickListener;
import android.widget.Button;
import android.widget.ProgressBar;
import android.widget.TextView;

public class MainActivity extends Activity {

    private Button btn_start;
    private ProgressBar mBar;
    private TextView tv_show_progress;
    //声明一个handler，用于在线程中发送消息修改界面的textView中的值
    private Handler mHandler = new Handler() {
        public void handleMessage(android.os.Message msg) {
            //根据progressBar的进度来设置textView中的值
            //设置progressBar的进度
            mBar.setProgress(msg.what);
            tv_show_progress.setText(msg.what+"");
        };
    };

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
        btn_start = (Button) findViewById(R.id.btn_start);
        mBar = (ProgressBar) findViewById(R.id.progressBar1);
        tv_show_progress = (TextView) findViewById(R.id.textView_show_progress);
        btn_start.setOnClickListener(new OnClickListener() {

            @Override
            public void onClick(View arg0) {
                //在单击事件中开一个线程来模拟后台扫描文件
                new Thread() {
                    public void run() {
                        //扫描过程中不能再次启动扫描，所以将BUTTON设置为不可点击
                        btn_start.setClickable(false);/////这句为什么不能用setenable


                        for (int i = 0; i < 101; i++) {



                            //在子线程中不能修改UI线程中数据，所以需要一个handler来发送消息修改
                            mHandler.sendEmptyMessage(i);
                            try {
                                Thread.sleep(500);
                            } catch (InterruptedException e) {
                                // TODO Auto-generated catch block
                                e.printStackTrace();
                            }
                        }
                        //扫描完成后将BUTTON还原成可点击的状态
                    btn_start.setClickable(true);
                    };
                }.start();

            }
        });

    }

    @Override
    public boolean onCreateOptionsMenu(Menu menu) {
        // Inflate the menu; this adds items to the action bar if it is present.
        getMenuInflater().inflate(R.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();
        if (id == R.id.action_settings) {
            return true;
        }
        return super.onOptionsItemSelected(item);
    }
}