android中Activity实现再按一次退出

Exit exit = new Exit();

    

  @Override

    public boolean onKeyDown(int keyCode, KeyEvent event) {

      if (keyCode == KeyEvent.KEYCODE_BACK) {

              pressAgainExit();

              return true;

              }



        return super.onKeyDown(keyCode, event);

    }

  

  private void pressAgainExit() {

          if (exit.isExit()) {

              finish();

          } else {

              Toast.makeText(getApplicationContext(), "再按一次退出程序",

                      1000).show();

              exit.doExitInOneSecond();

          }

      }

辅助类Exit.java

package com.chen.b;

import android.os.Handler;
import android.os.HandlerThread;

public class Exit {

    private boolean isExit = false;
        private Runnable task = new Runnable() {
            @Override
            public void run() {
                isExit = false;
            }
        };
     
        public void doExitInOneSecond() {
            isExit = true;
            HandlerThread thread = new HandlerThread("doTask");
            thread.start();
            new Handler(thread.getLooper()).postDelayed(task, 1000);
        }
         
        public boolean isExit() {
            return isExit;
        }
     
        public void setExit(boolean isExit) {
            this.isExit = isExit;
        }
    }