Java方法的参数是异步数据时，怎么确定在获取到数据之后才调用这个方法？

如题.
下面的代码中，需要用到一个Binder作为方法的参数。

执行bindService(intent, connection, Context.BIND_AUTO_CREATE);时，

会调用musicBinder = (BGMusicService.MusicBinder)service; 异步绑定Binder。

那么如何在执行webView.addJavascriptInterface(new JsInterface(DetailMusicActivity.this, musicBinder), "music");传递该Binder时，确保这个Binder不为空呢？

 private BGMusicService.MusicBinder musicBinder;
    private ServiceConnection connection = new ServiceConnection() {
        @Override
        public void onServiceConnected(ComponentName name, IBinder service) {
            musicBinder = (BGMusicService.MusicBinder)service;
            Log.d("BINDSERVICE", "-------------1bind------------");
        }

        @Override
        public void onServiceDisconnected(ComponentName name) {
        }
    };

    private WebView webView;
    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_detail_music);
        Toolbar toolbar = (Toolbar) findViewById(R.id.detail_music_toolbar);
        toolbar.setTitle(null);
        setSupportActionBar(toolbar);
        ActionBar actionBar = getSupportActionBar();
        if (actionBar != null){
            actionBar.setDisplayHomeAsUpEnabled(true);
        }

        TextView textView = (TextView)findViewById(R.id.detail_music_title);
        textView.setText(getIntent().getStringExtra("title"));
        textView.setTextColor(Color.BLACK);

        Intent intent = new Intent(DetailMusicActivity.this, BGMusicService.class);
        startService(intent);
        bindService(intent, connection, Context.BIND_AUTO_CREATE);

        webView = (WebView)findViewById(R.id.detail_music_webview);
        webView.addJavascriptInterface(new JsInterface(DetailMusicActivity.this, musicBinder), "music");
        webView.getSettings().setJavaScriptEnabled(true);
        webView.getSettings().setDomStorageEnabled(true);
        webView.setWebViewClient(new WebViewClient(){
            @Override
            public void onPageFinished(WebView view, String url) {
                super.onPageFinished(view, url);
                if (getIntent().getIntExtra("tag", 0) == ItemData.CONTENT_MUSIC){
                    webView.loadUrl(getJsFromFile("Javascript/remove"));
                    webView.loadUrl("javascript:remove()");
                }else if (getIntent().getIntExtra("tag", 0) == ItemData.CONTENT_FM){View.loadUrl(getJsFromFile("Javascript/removeAll"));
                    webView.loadUrl("javascript:removeAll()");
                }
            }
        });
        webView.setWebChromeClient(new WebChromeClient());
        webView.loadUrl(getIntent().getStringExtra("url"));
    }