java - 如何显示抽屉导航中的 fragment ？

Question

我无法找到使用 Android Studio 中的特定自动生成代码的问题。我想弄清楚当从抽屉导航中单击按钮时如何显示我拥有的布局？

这里是生成的MainActivity

    package com.oxinc.android.classaverage;

    import android.app.FragmentManager;
    import android.os.Bundle;
    import android.support.design.widget.FloatingActionButton;
    import android.support.design.widget.Snackbar;
    import android.view.View;
    import android.support.design.widget.NavigationView;
    import android.support.v4.view.GravityCompat;
    import android.support.v4.widget.DrawerLayout;
    import android.support.v7.app.ActionBarDrawerToggle;
    import android.support.v7.app.AppCompatActivity;
    import android.support.v7.widget.Toolbar;
    import android.view.Menu;
    import android.view.MenuItem;

    public class MainActivity extends AppCompatActivity
            implements NavigationView.OnNavigationItemSelectedListener {

        @Override
        protected void onCreate(Bundle savedInstanceState) {
            super.onCreate(savedInstanceState);
            setContentView(R.layout.activity_main);
            Toolbar toolbar = (Toolbar) findViewById(R.id.toolbar);
            setSupportActionBar(toolbar);

            FloatingActionButton fab = (FloatingActionButton) findViewById(R.id.fab);
            fab.setOnClickListener(new View.OnClickListener() {
                @Override
                public void onClick(View view) {
                    Snackbar.make(view, "Replace with your own action", Snackbar.LENGTH_LONG)
                            .setAction("Action", null).show();
                }
            });

            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);
            drawer.setDrawerListener(toggle);
            toggle.syncState();

            NavigationView navigationView = (NavigationView) findViewById(R.id.nav_view);
            navigationView.setNavigationItemSelectedListener(this);
        }

        @Override
        public void onBackPressed() {
            DrawerLayout drawer = (DrawerLayout) findViewById(R.id.drawer_layout);
            if (drawer.isDrawerOpen(GravityCompat.START)) {
                drawer.closeDrawer(GravityCompat.START);
            } else {
                super.onBackPressed();
            }
        }

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

        @Override
        public boolean onOptionsItemSelected(MenuItem item) {
            // 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.id.action_settings) {
                return true;
            }

            return super.onOptionsItemSelected(item);
        }

        @SuppressWarnings("StatementWithEmptyBody")
        @Override
        public boolean onNavigationItemSelected(MenuItem item) {
            // Handle navigation view item clicks here.
            int id = item.getItemId();

//This is the part I am having trouble with

            if (id == R.id.nav_camera) {
                // Handle the camera action
            } else if (id == R.id.nav_gallery) {

            } else if (id == R.id.nav_slideshow) {


            } else if (id == R.id.nav_manage) {

            } else if (id == R.id.nav_share) {

            } else if (id == R.id.nav_send) {
                //This is what I have come up with
                setContentView(R.layout.MyLayout)
            }

            DrawerLayout drawer = (DrawerLayout) findViewById(R.id.drawer_layout);
            drawer.closeDrawer(GravityCompat.START);
            return true;
        }
    }

提前谢谢您。

Answer 1

要显示一个 fragment ，您至少需要添加一个容器!下一步。让您的 android studio 默认类继承 FragmentActivity，相应地更改它们，或者您可以跳过此步骤。将 FrameLayout 放入实际放置内容的 Root View 中(android studio 默认使用抽屉为您创建了该框架)并且必须获取该 FrameLayout 的实例。创建一个类，例如 MyFragmenNumberOne.class 并让它继承 FRAGMENT 并确保使用 v4 作为旧版本的目标支持。之后您只需从fragmentManager调用patter代码来添加/删除/替换 fragment ，您将在其中传递 fragment 类和容器框架布局实例，就是这样。重要的是要提到，在调用beginTransaction.replace()时，第一个参数将不会被查看你的容器，但它的资源ID像R.id.myContainer，第二个参数是fragment的实例，它可以直接使用new关键字初始化，或者在fragment类中有一个静态newInstance()方法，该方法将创建一个实例一次在应用程序生命周期中使用它，这是更好的练习。无论如何，我帮助了你。