【Java 转 Android】58，讲的太清楚了

import java.util.Random;

public class MainActivity extends AppCompatActivity {

private DrawerLayout mDrawerLayout;

private Fruit[] fruits = {new Fruit("Apple", R.drawable.apple), new Fruit("Banana", R.drawable.banana),

new Fruit("Orange", R.drawable.orange), new Fruit("Watermelon", R.drawable.watermelon),

new Fruit("Pear", R.drawable.pear), new Fruit("Grape", R.drawable.grape),

new Fruit("Pineapple", R.drawable.pineapple), new Fruit("Strawberry", R.drawable.strawberry),

new Fruit("Cherry", R.drawable.cherry), new Fruit("Mango", R.drawable.mango)};

private List<Fruit> fruitList = new ArrayList<>();

private FruitAdapter adapter;

@Override

protected void onCreate(Bundle savedInstanceState) {

super.onCreate(savedInstanceState);

setContentView(R.layout.activity_main);

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

setSupportActionBar(toolbar);

mDrawerLayout = findViewById(R.id.drawer_layout);

NavigationView navView = findViewById(R.id.nav_view);

ActionBar actionBar = getSupportActionBar();

if (actionBar != null) {

actionBar.setDisplayHomeAsUpEnabled(true);

actionBar.setHomeAsUpIndicator(R.drawable.ic_menu);

}

navView.setCheckedItem(R.id.nav_call);

navView.setNavigationItemSelectedListener(new NavigationView.OnNavigationItemSelectedListener() {

@Override

public boolean onNavigationItemSelected(@NonNull MenuItem menuItem) {

mDrawerLayout.closeDrawers();

return true;

}

});

FloatingActionButton fab = findViewById(R.id.fab);

fab.setOnClickListener(new View.OnClickListener() {

@Override

public void onClick(View v) {

Snackbar.make(v,"FAB data deleted",Snackbar.LENGTH_SHORT)

.setAction("Undo", new View.OnClickListener() {

@Override

public void onClick(View v) {

Toast.makeText(MainActivity.this, "FAB Undo", Toast.LENGTH_SHORT).show();

}

}).show();

}

});

initFruits();

RecyclerView recyclerView = findViewById(R.id.recycler_view);

GridLayoutManager layoutManager = new GridLayoutManager(this, 2);

recyclerView.setLayoutManager(layoutManager);

adapter = new FruitAdapter(fruitList);

recyclerView.setAdapter(adapter);

}

private void initFruits() {

fruitList.clear();

for (int i = 0; i < 50; i++) {

Random random = new Random();

int index = random.nextInt(fruits.length);

fruitList.add(fruits[index]);

}

}

@Override

public boolean onCreateOptionsMenu(Menu menu) {

getMenuInflater().inflate(R.menu.toolbar,menu);

return true;

}

@Override

public boolean onOptionsItemSelected(MenuItem item) {

switch (item.getItemId()) {

case android.R.id.home:

mDrawerLayout.openDrawer(GravityCompat.START);

break;

case R.id.item1:

Toast.makeText(this, "You clicked Backup", Toast.LENGTH_SHORT).show();

break;

case R.id.item2:

Toast.makeText(this, "You clicked Delete", Toast.LENGTH_SHORT).show();

break;

case R.id.item3:

Toast.makeText(this, "You clicked Settings", Toast.LENGTH_SHORT).show();

break;

default:

}

return true;

}

}

package aystudio.nopi.materialdesign;

public class Fruit {

private String name;

private int imageId;

public Fruit(String name, int imageId) {

this.name = name;

this.imageId = imageId;

}

public String getName() {

return name;

}

public int getImageId() {

return imageId;

}

}

package aystudio.nopi.materialdesign;

import android.content.Context;

import android.content.Intent;

import android.support.v7.widget.CardView;

import android.support.v7.widget.RecyclerView;

import android.view.LayoutInflater;

import android.view.View;

import android.view.ViewGroup;

import android.widget.ImageView;

import android.widget.TextView;

import com.bumptech.glide.Glide;

import java.util.List;

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public class FruitAdapter extends RecyclerView.Adapter<FruitAdapter.ViewHolder>{

private static final String TAG = "FruitAdapter";

private Context mContext;

private List<Fruit> mFruitList;

static class ViewHolder extends RecyclerView.ViewHolder {

CardView cardView;

ImageView fruitImage;

TextView fruitName;

public ViewHolder(View view) {

super(view);

cardView = (CardView) view;

fruitImage = (ImageView) view.findViewById(R.id.fruit_image);

fruitName = (TextView) view.findViewById(R.id.fruit_name);

}

}

public FruitAdapter(List<Fruit> fruitList) {

mFruitList = fruitList;

}

@Override

public ViewHolder onCreateViewHolder(ViewGroup parent, int viewType) {

if (mContext == null) {

mContext = parent.getContext();

}

View view = LayoutInflater.from(mContext).inflate(R.layout.fruit_item, parent, false);

final ViewHolder holder = new ViewHolder(view);

holder.cardView.setOnClickListener(new View.OnClickListener() {

@Override

public void onClick(View v) {

}

});

return holder;

}

@Override

public void onBindViewHolder(ViewHolder holder, int position) {

Fruit fruit = mFruitList.get(position);