天天博客

    public boolean onKeyDown(int keyCode, KeyEvent event) {
        // TODO Auto-generated method stub
        if (keyCode == KeyEvent.KEYCODE_BACK) {
            if ((System.currentTimeMillis() - mExitTime) > 2000) {
                // Toast.makeText(MainActivity.this, "再按一次退出程序",
                // Toast.LENGTH_SHORT).show();
                // mExitTime = System.currentTimeMillis();

                AlertDialog alert = new AlertDialog.Builder(MainActivity.this)
                        .setIcon(R.drawable.ic_launcher)
                        .setTitle("提示")
                        .setMessage("您确定要退出么？")
                        .setPositiveButton("确定",
                                new DialogInterface.OnClickListener() {// 设置确定按钮
                                    @Override
                                    // 处理确定按钮点击事件
                                    public void onClick(DialogInterface dialog,
                                            int which) {
                                        finish();
                                    }
                                })
                        .setNegativeButton("取消",
                                new DialogInterface.OnClickListener() {// 设置取消按钮
                                    @Override
                                    // 取消按钮点击事件
                                    public void onClick(DialogInterface dialog,
                                            int which) {
                                        dialog.cancel();// 对话框关闭。
                                    }
                                }).create();
                alert.show();
            } else {
                finish();
            }
            return true;
        }
        return super.onKeyDown(keyCode, event);
    }