java - 如何在外部 Java 监听器中访问 getSupportFragmentManager

Question

我必须在主类中为 NavigationView 设置监听器。但是 main 将包含很多东西，我希望它尽可能“分离”。

所以我会在他们自己的 java 文件中做监听器，比如:

navigationView.setNavigationItemSelectedListener(new NavigationListener());

问题来了，我必须调用 getSupportFragmentManager ，但无法访问，所以，我想我需要做类似的事情:context.getSupportFragmentManager 来制作我的“工作”。

但我不知道如何获取上下文。

我怎样才能得到它？

监听类:

public class NavigationListener implements NavigationView.OnNavigationItemSelectedListener {
    @Override
    public boolean onNavigationItemSelected(MenuItem item) {
        boolean fragmentTransaction = false;
        String TAG = "NavigationViewListener";
        Logger.init(TAG);
        Fragment fragment = null;
        switch (item.getItemId()){
            case R.id.nav_home:
                fragment = new FragmentHome();
                fragmentTransaction = true;
                break;
            case R.id.nav_map:
                fragment = new FragmentMap();
                fragmentTransaction = true;
                break;
            case R.id.nav_log_out:
                Logger.d("Pulsada opnción de LogOut");
                break;
        }

        if(fragmentTransaction){
            getSupportFragmentManager().beginTransaction()
                    .replace(R.id.main_content, fragment)
                    .commit();

            item.setChecked(true);
            getSupportActionBar().setTitle(item.getTitle());
        }
    }
}

Answer 1

您可以将 FragmentActivity 的实例作为构造函数参数传递给 NavigationListener:

public class NavigationListener implements NavigationView.OnNavigationItemSelectedListener {

    FragmentActivity activity;        

    public NavigationListener(FragmentActivity activity) {
        this.activity = activity;
    }

    @Override
    public boolean onNavigationItemSelected(MenuItem item) {

        // ...

        if(fragmentTransaction){
            activity.getSupportFragmentManager().beginTransaction()
                .replace(R.id.main_content, fragment)
                .commit();

            // ...
        }
    }
}

从您的FragmentActivity:

navigationView.setNavigationItemSelectedListener(new NavigationListener(this));