java - 找不到类 ArrayAdapter 和 listAdapter 的符号

Question

大家好，我正在 android studio 中做一个 listiview，当我设置 listview 并使用下面的代码时，我遇到了这一系列错误。我该如何解决这些问题？

下面除了java代码之外我还添加了xml代码

错误:

错误:找不到符号类ArrayAdapter
错误:找不到符号变量 listAdapter

家庭 Activity :

package viewsoftware.quote;


import android.os.Bundle;
import android.support.design.widget.FloatingActionButton;
import android.support.design.widget.Snackbar;
import android.support.v7.app.AppCompatActivity;
import android.support.v7.widget.Toolbar;
import android.widget.ListView;
import android.view.View;
import java.util.*;

public class HomeActivity extends AppCompatActivity {

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

        ListView  cantieriListView = (ListView) findViewById( R.id.ListViewCantieri );
        // Create and populate a List of planet names.
        String[] planets = new String[] { "Mercury", "Venus", "Earth", "Mars",
                "Jupiter", "Saturn", "Uranus", "Neptune"};
        ArrayList<String> planetList = new ArrayList<String>();
        planetList.addAll( Arrays.asList(planets) );

        // Create ArrayAdapter using the planet list.
        listAdapter = new ArrayAdapter<String>(this, R.layout.row, planetList);

        // Add more planets. If you passed a String[] instead of a List<String>
        // into the ArrayAdapter constructor, you must not add more items.
        // Otherwise an exception will occur.
        listAdapter.add( "Ceres" );
        listAdapter.add( "Pluto" );
        listAdapter.add( "Haumea" );
        listAdapter.add( "Makemake" );
        listAdapter.add( "Eris" );

        // Set the ArrayAdapter as the ListView's adapter.
        cantieriListView.setAdapter( listAdapter );


    }

}

acitivity_home.xml:

<?xml version="1.0" encoding="utf-8"?>
<android.support.design.widget.CoordinatorLayout
        xmlns:android="http://schemas.android.com/apk/res/android"
        xmlns:app="http://schemas.android.com/apk/res-auto"
        xmlns:tools="http://schemas.android.com/tools"
        android:layout_width="match_parent"
        android:layout_height="match_parent"
        tools:context=".HomeActivity">

    <android.support.design.widget.AppBarLayout
            android:layout_height="wrap_content"
            android:layout_width="match_parent"
            android:theme="@style/AppTheme.AppBarOverlay">

        <android.support.v7.widget.Toolbar
                android:id="@+id/toolbar"
                android:layout_width="match_parent"
                android:layout_height="?attr/actionBarSize"
                android:background="?attr/colorPrimary"
                app:popupTheme="@style/AppTheme.PopupOverlay"/>

    </android.support.design.widget.AppBarLayout>

    <include layout="@layout/content_home" android:id="@+id/include"/>

    <android.support.design.widget.FloatingActionButton
            android:id="@+id/fab"
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"
            android:layout_gravity="bottom|end"
            android:layout_margin="@dimen/fab_margin"
            app:srcCompat="@android:drawable/ic_dialog_email"/>



</android.support.design.widget.CoordinatorLayout>

row.xml:

<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
              android:layout_width="match_parent"
              android:layout_height="match_parent">

    <TextView xmlns:android="http://schemas.android.com/apk/res/android"
              android:id="@+id/rowTextView"
              android:layout_width="fill_parent"
              android:layout_height="wrap_content"
              android:padding="10dp"
              android:textSize="16sp" >
    </TextView>

</LinearLayout>

Answer 1

您缺少导入和变量声明:

import android.widget.ArrayAdapter;
...

public class HomeActivity extends AppCompatActivity {
    final ArrayAdapter<String> listAdapter ;
    ...
}