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java - 类必须声明为抽象的还是实现的？

问题描述

我不明白为什么我的代码不起作用？

我总是有类必须被声明为抽象或实现抽象方法： 

public class MainActivity extends AppCompatActivity implements MyRecyclerViewAdapter.ItemClickListener  {

    MyRecyclerViewAdapter adapter;

    private BottomNavigationView.OnNavigationItemSelectedListener mOnNavigationItemSelectedListener = new BottomNavigationView.OnNavigationItemSelectedListener() {

        @Override
        public boolean onNavigationItemSelected(@NonNull MenuItem item) {
            switch (item.getItemId()) {

                case R.id.navigation_home:

                return true;
                case R.id.navigation_public:


                return true;    

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
        BottomNavigationView navView = findViewById(R.id.nav_view);
        mTextMessage = findViewById(R.id.message);
        navView.setOnNavigationItemSelectedListener(mOnNavigationItemSelectedListener);

        ArrayList<String> mImageUrls = new ArrayList<>();
        ArrayList<String> mNames = new ArrayList<>();

        mImageUrls.add("https://c1.staticflickr.com/5/4636/25316407448_de5fbf183d_o.jpg");
        mNames.add("Havasu Falls");

        mImageUrls.add("https://i.redd.it/tpsnoz5bzo501.jpg");
        mNames.add("Trondheim");

        // set up the RecyclerView
        RecyclerView recyclerView = findViewById(R.id.recycler_public);
        recyclerView.setLayoutManager(new LinearLayoutManager(this));
        adapter = new MyRecyclerViewAdapter(this, mImageUrls);
        adapter.setClickListener(this);
        recyclerView.setAdapter(adapter);

    }
}

标签： javaandroid

解决方案

我找到了答案……我忘记了：

@Override
    public void onItemClick(View view, int position) {
        Toast.makeText(this, "You clicked " + adapter.getItem(position) + " on row number " + position, Toast.LENGTH_SHORT).show();
    }

对不起...

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