如何重写默认方法?

我们有这行代码 A级

 drawer.addDrawerListener(toggle);

ctrl + left click

public void addDrawerListener(@NonNull DrawerListener listener) {
        if (listener == null) {
            return;
        }
        if (mListeners == null) {
            mListeners = new ArrayList<DrawerListener>();
        }
        mListeners.add(listener);
    }

我们想展示一下 null 如果侦听器是 ,所以我们 Override 此方法并添加到 .

    @Override
    public void addDrawerListener(@NonNull DrawerLayout.DrawerListener listener) {
        if (listener == null) {
            Toast.makeText(getApplication(),"null",Toast.LENGTH_LONG).show();
            return;
        }
        if (mListeners == null) {
            mListeners = new ArrayList<DrawerLayout.DrawerListener>();
        }
        mListeners.add(listener);
    }

但后来我们

Method does not override method from its superclass

如果我们想改变,我们该怎么办 addDrawerListener ?

我的类是扩展到AppCompatActivity

@Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);

        Toolbar toolbar = (Toolbar) findViewById(R.id.toolbar);
        toolbar = (Toolbar) findViewById(R.id.toolbar);
        setSupportActionBar(toolbar);

        DrawerLayout drawer = (DrawerLayout) findViewById(R.id.drawer_layout);
        ActionBarDrawerToggle toggle = new ActionBarDrawerToggle(
                this, drawer, toolbar, R.string.navigation_drawer_open, R.string.navigation_drawer_close);

        if (savedInstanceState == null) {
            Toast.makeText(getApplication(), "null", Toast.LENGTH_LONG).show();
            RssFragment fragment = new RssFragment();
            FragmentTransaction fragmentTransaction = getSupportFragmentManager().beginTransaction();
            fragmentTransaction.replace(R.id.fragment_container, fragment);
            fragmentTransaction.commit();
        }

        drawer.addDrawerListener(toggle);

    }

添加部分代码后导航抽屉不工作

 if (savedInstanceState == null) {
            Toast.makeText(getApplication(), "null", Toast.LENGTH_LONG).show();
            RssFragment fragment = new RssFragment();
            FragmentTransaction fragmentTransaction = getSupportFragmentManager().beginTransaction();
            fragmentTransaction.replace(R.id.fragment_container, fragment);
            fragmentTransaction.commit();
        }

但如果我取下,导航抽屉可以正常工作。我们想从那里调试。