menu

@Override
    public boolean onCreateOptionsMenu(Menu menu) {
        menu.add(0,0,0,"关于");
        menu.add(0,1,1,"退出");
        return super.onCreateOptionsMenu(menu);
    }

    @Override
    public boolean onOptionsItemSelected(MenuItem item) {
        switch(item.getItemId()){
            case 1:
                AlertDialog.Builder builder=new AlertDialog.Builder(this).setTitle("退出").setMessage("确定要退出吗?").setPositiveButton("取消", new DialogInterface.OnClickListener() {
                    @Override
                    public void onClick(DialogInterface dialog, int which) {
                      alertDialog.dismiss();
                    }
                }).setNegativeButton("确定",new DialogInterface.OnClickListener(){

                    @Override
                    public void onClick(DialogInterface dialog, int which) {
                        finish();
                    }
                }).setCancelable(false);
                alertDialog=builder.create();
                alertDialog.show();
                break;
        }
        return super.onOptionsItemSelected(item);
    }