Java ListView中使用ArrayList时出错
我有5个数组列表,分别是Java ListView中使用ArrayList时出错,java,android,Java,Android,我有5个数组列表,分别是myMeat,myVeg,myDairy,myFruit,mySauce,它们都有一系列的成分名称 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="
myMeat
,myVeg
,myDairy
,myFruit
,mySauce
,它们都有一系列的成分名称
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>
我的活动XML代码如下所示
打开活动时,它会崩溃
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!");
}
公共类MyComponents扩展AppCompative活动
实现NavigationView.OnNavigationItemSelectedListener{
ArrayList myVeg;
ArrayList myMeat;
ArrayList mySpices;
阿雷利斯特·迈苏克斯;
ArraylistMyDairy;
排果;
列表视图;
列表视图列表;
ListView spicesList;
ListView酱汁列表;
ListView奶牛场;
列表视图水果列表;
@凌驾
创建时受保护的void(Bundle savedInstanceState){
super.onCreate(savedInstanceState);
设置内容视图(R.layout.my_ing);
Toolbar Toolbar=(Toolbar)findViewById(R.id.Toolbar);
设置支持操作栏(工具栏);
FloatingActionButton fab=(FloatingActionButton)findViewById(R.id.fab);
fab.setOnClickListener(新视图.OnClickListener(){
@凌驾
公共void onClick(视图){
Snackbar.make(查看“替换为您自己的操作”,Snackbar.LENGTH\u LONG)
.setAction(“Action”,null).show();
}
});
抽屉布局抽屉=(抽屉布局)findViewById(R.id.抽屉布局);
ActionBarDrawerToggle切换=新建ActionBarDrawerToggle(
这,抽屉,工具栏,R.string.navigation\u drawer\u open,R.string.navigation\u drawer\u close);
抽屉。设置抽屉定位器(开关);
toggle.syncState();
NavigationView NavigationView=(NavigationView)findViewById(R.id.nav_视图);
navigationView.setNavigationItemSelectedListener(此);
Log.d(“Cat”,“第一个检查点!”);
addChecking();
Log.d(“Cat”,“第四个检查点!”);
vegList=(ListView)findViewById(R.id.myVegList);
meatList=(ListView)findViewById(R.id.myMeatList);
spicesList=(ListView)findViewById(R.id.mySpicesList);
SauceList=(ListView)findViewById(R.id.mySauceList);
dairyList=(ListView)findViewById(R.id.myDairyList);
水果列表=(ListView)findViewById(R.id.MyFroutsList);
Log.d(“Cat”,“第五检查点!”);
ArrayAdapter veggies=新的ArrayAdapter(这个,android.R.layout.simple\u list\u item\u 1,myVeg);
vegList.setAdapter(蔬菜);
Log.d(“Cat”,“第6个检查点!”);
ArrayAdapter meat=新的ArrayAdapter(这个,android.R.layout.simple\u list\u item\u 1,myMeat);
蔬菜列表.肉;
Log.d(“Cat”,“第7个检查点!”);
ArrayAdapter spices=新的ArrayAdapter(这是android.R.layout.simple\u list\u item\u 1,mySpices);
蔬菜列表。setAdapter(香料);
Log.d(“Cat”,“第8个检查点!”);
ArrayAdapter sauces=新的ArrayAdapter(这是android.R.layout.simple\u list\u item\u 1,mySauces);
蔬菜列表:调味料;
Log.d(“Cat”,“第9个检查点!”);
ArrayAdapter fruits=新的ArrayAdapter(这个,android.R.layout.simple\u list\u item\u 1,myFruits);
蔬菜列表。setAdapter(水果);
Log.d(“Cat”,“最终检查点!”);
}
数组列表在方法addCheckedIng();
中填写
代码中未显示此信息。如果需要,请评论并索取
它只到达第5个检查点,活动崩溃,请帮助我解决。您崩溃是因为myVeg、myMeat等为空。您需要实例化ArrayList对象,然后再将它们添加到适配器。请检查您的my veg列表。它为空。 在创建数组适配器的对象之前添加此代码
myveg = new ArrayList<String>();
myveg.add("Vegetable");
myveg=newarraylist();
我的蔬菜添加(“蔬菜”);
很抱歉,我是一个初学者,不知道stacktrace是什么。感谢您6次指出veglist上的适配器,是的,我的活动中有6个列表视图。这是一个问题吗?嗯,您能提供一些示例代码说明如何做到这一点吗?myVeg=new ArrayList();然后是myVeg.add(“veg name”);ArrayList myVeg,myMeat,mypices,myauces,myDairy,myFruits=new ArrayList();不,您需要单独执行。ArrayList myVeg=new arrarylist();然后ArrayList myMeat=new arrarylist();对于每个ArrayList myVeg,myMeat,mypices,myauces,myDairy,myFruits=new ArrayList();我在课程开始时添加了它。请在数组列表中添加一些项,如myveg.add(“蔬菜”);在创建listview之前会调用此方法。在此方法中,会添加成分。