我有 5 个数组列表，分别是 myMeat、myVeg、myDairy、myFruit、mySauce code> 其中都有一堆成分名称。
My XML code for the activity is as below
<?xml version="1.0" encoding="utf-8"?>
<ScrollView 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">
<RelativeLayout
android:layout_width="match_parent"
android:layout_height="match_parent"
android:paddingBottom="@dimen/activity_vertical_margin"
android:paddingLeft="@dimen/activity_horizontal_margin"
android:paddingRight="@dimen/activity_horizontal_margin"
android:paddingTop="@dimen/activity_vertical_margin"
app:layout_behavior="@string/appbar_scrolling_view_behavior"
tools:context="com.viv.droidchef.MyIngredients"
tools:showIn="@layout/app_bar_my_ingredients">
<TextView
android:id="@+id/myVeg"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_alignParentStart="true"
android:layout_alignParentTop="true"
android:layout_marginTop="40dp"
android:text="Vegetables:"
android:textAppearance="?android:attr/textAppearanceLarge" />
<ListView
android:id="@+id/myVegList"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_alignParentStart="true"
android:layout_below="@+id/myVeg" />
<TextView
android:id="@+id/myMeat"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_alignParentLeft="true"
android:layout_alignParentStart="true"
android:layout_below="@+id/myVegList"
android:text="Meat:"
android:textAppearance="?android:attr/textAppearanceLarge" />
<ListView
android:id="@+id/myMeatList"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_alignParentStart="true"
android:layout_below="@+id/myMeat" />
<TextView
android:id="@+id/mySpices"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_alignParentLeft="true"
android:layout_alignParentStart="true"
android:layout_below="@+id/myMeatList"
android:text="Spices:"
android:textAppearance="?android:attr/textAppearanceLarge" />
<ListView
android:id="@+id/mySpicesList"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_alignParentStart="true"
android:layout_below="@+id/mySpices" />
<TextView
android:id="@+id/mySauces"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_alignParentLeft="true"
android:layout_alignParentStart="true"
android:layout_below="@+id/mySpicesList"
android:text="Sauces:"
android:textAppearance="?android:attr/textAppearanceLarge" />
<ListView
android:id="@+id/mySaucesList"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_alignParentStart="true"
android:layout_below="@+id/mySauces" />
<TextView
android:id="@+id/myDairy"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_alignParentLeft="true"
android:layout_alignParentStart="true"
android:layout_below="@+id/mySaucesList"
android:text="Dairy:"
android:textAppearance="?android:attr/textAppearanceLarge" />
<ListView
android:id="@+id/myDairyList"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_alignParentStart="true"
android:layout_below="@+id/myDairy" />
<TextView
android:id="@+id/myFruits"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_alignParentLeft="true"
android:layout_alignParentStart="true"
android:layout_below="@+id/myDairyList"
android:text="Fruits:"
android:textAppearance="?android:attr/textAppearanceLarge" />
<ListView
android:id="@+id/myFruitsList"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_alignParentStart="true"
android:layout_below="@+id/myFruits" />
</RelativeLayout>
</ScrollView>
打开 Activity 时崩溃。
现在在Java页面中，
public class MyIngredients extends AppCompatActivity
implements NavigationView.OnNavigationItemSelectedListener {
ArrayList<String> myVeg;
ArrayList<String> myMeat;
ArrayList<String> mySpices;
ArrayList<String> mySauces;
ArrayList<String> myDairy;
ArrayList<String> myFruits;
ListView vegList;
ListView meatList;
ListView spicesList;
ListView saucesList;
ListView dairyList;
ListView fruitsList;
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.my_ing);
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);
Log.d("Cat", "1st Checkpoint!");
addCheckedIng();
Log.d("Cat", "4th Checkpoint!");
vegList = (ListView) findViewById(R.id.myVegList);
meatList = (ListView) findViewById(R.id.myMeatList);
spicesList = (ListView) findViewById(R.id.mySpicesList);
saucesList = (ListView) findViewById(R.id.mySaucesList);
dairyList = (ListView) findViewById(R.id.myDairyList);
fruitsList = (ListView) findViewById(R.id.myFruitsList);
Log.d("Cat", "5th Checkpoint!");
ArrayAdapter<String> veggies = new ArrayAdapter<String>(this,android.R.layout.simple_list_item_1,myVeg);
vegList.setAdapter(veggies);
Log.d("Cat", "6th Checkpoint!");
ArrayAdapter<String> meat = new ArrayAdapter<String>(this,android.R.layout.simple_list_item_1,myMeat);
vegList.setAdapter(meat);
Log.d("Cat", "7th Checkpoint!");
ArrayAdapter<String> spices = new ArrayAdapter<String>(this,android.R.layout.simple_list_item_1,mySpices);
vegList.setAdapter(spices);
Log.d("Cat", "8th Checkpoint!");
ArrayAdapter<String> sauces = new ArrayAdapter<String>(this,android.R.layout.simple_list_item_1,mySauces);
vegList.setAdapter(sauces);
Log.d("Cat", "9th Checkpoint!");
ArrayAdapter<String> fruits = new ArrayAdapter<String>(this,android.R.layout.simple_list_item_1,myFruits);
vegList.setAdapter(fruits);
Log.d("Cat", "FINAL Checkpoint!");
}
数组列表在方法 addCheckedIng(); 中填充。
这还没有在代码中显示。如果需要，请发表评论并索取。
它只到达第 5 个检查点， Activity 就崩溃了，请帮帮我。
最佳答案
你正在崩溃，因为 myVeg、myMeat 等都是空的。在将 ArrayList 对象添加到适配器之前，您需要实例化它们。
关于java - 使用 ArrayLists 的 ListView 中的错误，我们在Stack Overflow上找到一个类似的问题： https://stackoverflow.com/questions/33704948/