在导航抽屉项目单击上启动新活动

Question

我知道这是一个经常被问到的问题，但是在阅读了有关堆栈溢出的许多问题和解决方案后，我感到很困惑。我对Fragments 以及从单击导航抽屉中的项目开始活动所需的内容感到困惑。

我检查了这些帖子，但只是感到困惑 Q1, Q2

有人能解释一下从这个导航抽屉项目开始基本活动需要什么吗？我是否需要在代码中指定的地方实现onClick 方法？还有这与 Intent 有什么关系？

这是我的 MainActivity.java

import android.content.res.Configuration;
import android.os.Bundle;
import android.support.design.widget.NavigationView;
import android.support.v4.widget.DrawerLayout;
import android.support.v7.app.ActionBarDrawerToggle;
import android.support.v7.app.AppCompatActivity;
import android.view.Menu;
import android.view.MenuItem;

public class MainActivity extends AppCompatActivity {

DrawerLayout drawerLayout;
ActionBarDrawerToggle drawerToggle;
NavigationView navigation;

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

private void initInstances() {
    getSupportActionBar().setHomeButtonEnabled(true);
    getSupportActionBar().setDisplayHomeAsUpEnabled(true);

    drawerLayout = (DrawerLayout) findViewById(R.id.drawerLayout);
    drawerToggle = new ActionBarDrawerToggle(MainActivity.this, drawerLayout, R.string.hello_world, R.string.hello_world);
    drawerLayout.setDrawerListener(drawerToggle);

    navigation = (NavigationView) findViewById(R.id.navigation_view);
    navigation.setNavigationItemSelectedListener(new NavigationView.OnNavigationItemSelectedListener() {
        @Override
        public boolean onNavigationItemSelected(MenuItem menuItem) {
            int id = menuItem.getItemId();
            switch (id) {
                case R.id.navigation_item_1:
                    //Do some thing here
                    // add navigation drawer item onclick method here
                    break;
                case R.id.navigation_item_2:
                    //Do some thing here
                    // add navigation drawer item onclick method here
                    break;
                case R.id.navigation_item_3:
                    //Do some thing here
                    // add navigation drawer item onclick method here
                    break;
                case R.id.navigation_item_4:
                    //Do some thing here
                    // add navigation drawer item onclick method here
                    break;
                case R.id.navigation_item_5:
                    //Do some thing here
                    // add navigation drawer item onclick method here
                    break;
            }
            return false;
        }
    });

}

@Override
public void onPostCreate(Bundle savedInstanceState) {
    super.onPostCreate(savedInstanceState);
    drawerToggle.syncState();
}

@Override
public void onConfigurationChanged(Configuration newConfig) {
    super.onConfigurationChanged(newConfig);
    drawerToggle.onConfigurationChanged(newConfig);
}

@Override
public boolean onCreateOptionsMenu(Menu menu) {
    // Inflate the menu; this adds items to the action bar if it is present.
    getMenuInflater().inflate(R.menu.navigation_view_items, menu);
    return true;
}

@Override
public boolean onOptionsItemSelected(MenuItem item) {
    if (drawerToggle.onOptionsItemSelected(item))
        return true;

    // Handle action bar item clicks here. The action bar will
    // automatically handle clicks on the Home/Up button, so long
    // as you specify a parent activity in AndroidManifest.xml.
    int id = item.getItemId();

    //noinspection SimplifiableIfStatement
    if (id == R.string.action_settings) {
        return true;
    }

    return super.onOptionsItemSelected(item);
}

这是第二个活动 Playboard.java，它只是加载背景图像：

import android.app.Activity;
import android.support.v7.app.AppCompatActivity;
import android.os.Bundle;

public class Playboard extends Activity {
    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_playboard);
    }
}

非常感谢所有输入！

Answer 1

对于每个 case 语句，您只需通过 Intent 指定要从哪个 Activity 开始。

假设您想在选择navigation_item_1 时启动Playboard 活动。

您可以将此代码添加到特定的case。

case R.id.navigation_item_1:
    Intent i = new Intent(MainActivity.this, Playboard.class);
    startActivity(i);
    break;

Answer 2

代替

NavigationUI.setupWithNavController(navigationView, navController);

这样做

navigationView.setNavigationItemSelectedListener(new 
    NavigationView.OnNavigationItemSelectedListener() {
        @Override
        public boolean onNavigationItemSelected(@NonNull MenuItem item) { 
            Toast.makeText(MainActivity.this, "clicked", Toast.LENGTH_SHORT).show();
            return false;
        }
    }
);

Answer 3

警告一句：如果您在抽屉盒上有任何动画，直接从主线程启动一个活动会导致动画过早结束并且看起来很奇怪。要解决此问题，您可以执行以下操作（代码使用 retrolambda 来美观，但这不是必需的）：

Class<? extends Activity> activityClass = null;
switch (menuItem.getItemId()) {
  case R.id.navigation_item_1:
    activityClass = MainActivity.class;
    break;
 }

 final Class<?> finalActivityClass = activityClass;
 Executors.newSingleThreadExecutor().execute(() -> {
   Intent intent = new Intent(getApplicationContext(), finalActivityClass);
   startActivity(intent);
 });

 menuItem.setChecked(true);
 mDrawerLayout.closeDrawers();