AlertDialog.Builder builder = new AlertDialog.Builder(context);
builder.setTitle("警告");
builder.setMessage("你已被强制下线，请重新登录");
builder.setCancelable(false);    //设置不可取消
builder.setPositiveButton("确认", new DialogInterface.OnClickListener() {
    @Override
    public void onClick(DialogInterface dialogInterface, int i) {
        //实现确认后的代码
    }
});
builder.show();