这是应该显示联系信息的 Activity 。如您所见，此 Activity 将显示联系人的基本信息，例如姓名、手机等。它还必须显示相应联系人的地址列表。
public class ViewContactActivity extends Activity
{
private TextView name;
private TextView cellphone;
private TextView displayCellphone;
private TextView workphone;
private TextView displayWorkphone;
private TextView email;
private TextView displayEmail;
private ListView listView;
private Contact contact;
private ArrayList<Address> addressList;
@Override
protected void onCreate(Bundle savedInstanceState)
{
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_view_contact);
this.name = (TextView) findViewById(R.id.nameTextView);
this.cellphone = (TextView) findViewById(R.id.cellViewTextView);
this.displayCellphone = (TextView) findViewById(R.id.cellDisplayTextView);
this.workphone = (TextView) findViewById(R.id.workViewTextView);
this.displayWorkphone = (TextView) findViewById(R.id.workDisplayTextView);
this.email = (TextView) findViewById(R.id.emailViewTextView);
this.displayEmail = (TextView) findViewById(R.id.emailDisplayTextView);
this.listView = (ListView) findViewById(R.id.addressListView);
Intent i = getIntent();
contact = (Contact) i.getSerializableExtra("Contact");
this.name.setText(contact.getFirstName() + " " + contact.getLastName());
this.displayCellphone.setText(contact.getCellPhone());
this.displayWorkphone.setText(contact.getWorkPhone());
this.displayEmail.setText(contact.getEmail());
}
protected void onResume()
{
super.onResume();
this.addressList = contact.getAddresses();
populateList();
}
@Override
public boolean onCreateOptionsMenu(Menu menu)
{
// Inflate the menu; this adds items to the action bar if it is present.
getMenuInflater().inflate(R.menu.view_contact, menu);
return true;
}
public boolean onOptionsItemSelected(MenuItem item)
{
switch (item.getItemId())
{
case android.R.id.home:
NavUtils.navigateUpFromSameTask(this);
return true;
}
return onOptionsItemSelected(item);
}
private void populateList() {
ArrayAdapter<Address> adapter = new AddressListAdapter();
listView.setAdapter(adapter);
}
private class AddressListAdapter extends ArrayAdapter<Address> {
public AddressListAdapter() {
super (ViewContactActivity.this, R.layout.address_listview_item, addressList);
}
@Override
public View getView(int position, View view, ViewGroup parent) {
if (view == null)
view = getLayoutInflater().inflate(R.layout.address_listview_item, parent, false);
Address address = addressList.get(position);
TextView addressName = (TextView) findViewById(R.id.addressNameTextView);
addressName.setText(address.getAddressName());
TextView addressStreet = (TextView) findViewById(R.id.streetDisplayTextView);
addressStreet.setText(address.getAddressStreet());
TextView addressNumber = (TextView) findViewById(R.id.numberDisplayTextView);
addressNumber.setText(address.getAddressNumber());
TextView addressCity = (TextView) findViewById(R.id.cityDisplayTextView);
addressCity.setText(address.getAddressCity());
TextView addressState = (TextView) findViewById(R.id.stateDisplayTextView);
addressState.setText(address.getAddressState());
TextView addressZip = (TextView) findViewById(R.id.zipDisplayTextView);
addressZip.setText(address.getAddressZip());
return view;
}
}
}
这是主要 Activity 。当用户点击联系人时，它会启动 ViewContactActivity。
public class MainActivity extends Activity
{
private ListView listView;
ShowFieldsNewContactActivity activity = new ShowFieldsNewContactActivity();
public static ContactsManager cManager = new ContactsManager();
private Object[] Contacts;
@Override
protected void onCreate(Bundle savedInstanceState)
{
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
this.listView = (ListView) findViewById(R.id.contactListView);
}
protected void onResume()
{
super.onResume();
Contacts = cManager.getContactListObj();
this.listView.setOnItemClickListener(new OnItemClickListener()
{
@Override
public void onItemClick(AdapterView<?> arg0, View arg1, int arg2,
long arg3) {
Intent intent = new Intent(MainActivity.this, ViewContactActivity.class);
intent.putExtra("Contact", (Contact) Contacts[arg2]);
startActivity(intent);
}
});
populateList();
}
@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)
{
switch(item.getItemId())
{
case R.id.add_contact:
Intent intent = new Intent(MainActivity.this, ShowFieldsNewContactActivity.class);
startActivity(intent);
//adapter.notifyDataSetChanged();
return true;
default:
return super.onOptionsItemSelected(item);
}
}
private void populateList() {
ArrayAdapter<Object> adapter = new ContactListAdapter();
listView.setAdapter(adapter);
}
private class ContactListAdapter extends ArrayAdapter<Object> {
public ContactListAdapter() {
super (MainActivity.this, R.layout.listview_item, Contacts);
}
@Override
public View getView(int position, View view, ViewGroup parent) {
if (view == null)
view = getLayoutInflater().inflate(R.layout.listview_item, parent, false);
Contact currentContact = (Contact) Contacts[position];
TextView name = (TextView) view.findViewById(R.id.contactName);
name.setText(currentContact.getFirstName() + " " + currentContact.getLastName());
TextView phone = (TextView) view.findViewById(R.id.phoneNumber);
phone.setText(currentContact.getCellPhone());
TextView email = (TextView) view.findViewById(R.id.emailAddress);
email.setText(currentContact.getEmail());
return view;
}
}
}
联系 Activity
@SuppressWarnings("serial")
public class Contact implements Comparable<Contact>, Serializable
{
private String firstName;
private String lastName;
private String cellPhone;
private String workPhone;
private String email;
private ArrayList<Address> addresses;
public Contact(String firstName, String lastName, String cellPhone, String workPhone, String email)
{
this.firstName = firstName;
this.lastName = lastName;
this.cellPhone = cellPhone;
this.workPhone = workPhone;
this.email = email;
this.addresses = new ArrayList<Address>();
}
public String getFirstName()
{
return firstName;
}
public void setFirstName(String firstName)
{
this.firstName = firstName;
}
public String getLastName()
{
return lastName;
}
public void setLastName(String lastName)
{
this.lastName = lastName;
}
public String getCellPhone()
{
return cellPhone;
}
public void setCellPhone(String cellPhone)
{
this.cellPhone = cellPhone;
}
public String getWorkPhone()
{
return workPhone;
}
public void setWorkPhone(String workPhone)
{
this.workPhone = workPhone;
}
public String getEmail()
{
return email;
}
public void setEmail(String email)
{
this.email = email;
}
public void addAddress(Address address1)
{
this.addresses.add(address1);
}
public ArrayList<Address> getAddresses()
{
return this.addresses;
}
@Override
public int compareTo(Contact another) {
// TODO Auto-generated method stub
return 0;
}
}
添加地址 Activity
public class AddAdressActivity extends Activity
{
private TextView addressName;
private TextView addressStreet;
private TextView addressNumber;
private TextView addressCity;
private TextView addressState;
private TextView addressZip;
private EditText addressNameEditText;
private EditText addressStreetEditText;
private EditText addressNumberEditText;
private EditText addressCityEditText;
private EditText addressStateEditText;
private EditText addressZipEditText;
public static Contact contact;
@Override
protected void onCreate(Bundle savedInstanceState)
{
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_add_adress);
this.addressName = (TextView) findViewById(R.id.adressNameTextView);
this.addressStreet = (TextView) findViewById(R.id.streetTextView);
this.addressNumber = (TextView) findViewById(R.id.numberTextView);
this.addressCity = (TextView) findViewById(R.id.cityTextView);
this.addressState = (TextView) findViewById(R.id.stateTextView);
this.addressZip = (TextView) findViewById(R.id.zipTextView);
this.addressNameEditText = (EditText) findViewById(R.id.adreesNameEditText);
this.addressStreetEditText = (EditText) findViewById(R.id.streetEditText);
this.addressNumberEditText = (EditText) findViewById(R.id.numberEditText);
this.addressCityEditText = (EditText) findViewById(R.id.cityEditText);
this.addressStateEditText = (EditText) findViewById(R.id.stateEditText);
this.addressZipEditText = (EditText) findViewById(R.id.zipEditText);
Intent i = getIntent();
contact = (Contact) i.getSerializableExtra("Contact");
}
@Override
public boolean onCreateOptionsMenu(Menu menu)
{
// Inflate the menu; this adds items to the action bar if it is present.
getMenuInflater().inflate(R.menu.add_adress, menu);
return true;
}
public boolean onOptionsItemSelected(MenuItem item)
{
switch (item.getItemId())
{
case android.R.id.home:
NavUtils.navigateUpFromSameTask(this);
return true;
case R.id.save_contact:
Address address = new Address(this.addressNameEditText.getText().toString(), this.addressStreetEditText.getText().toString(),
this.addressNumberEditText.getText().toString(), this.addressCity.getText().toString(), this.addressStateEditText
.getText().toString(), this.addressZipEditText.getText().toString());
MainActivity.cManager.addContact(contact);
contact.addAddress(address);
finish();
return true;
}
return super.onOptionsItemSelected(item);
}
}
这是用于查看联系人 Activity 的 XML 文件
<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:tools="http://schemas.android.com/tools"
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"
tools:context=".ViewContactActivity" >
<TextView
android:id="@+id/nameTextView"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_alignParentTop="true"
android:layout_centerHorizontal="true"
android:layout_marginTop="16dp"
android:text="Large Text"
android:textAppearance="?android:attr/textAppearanceLarge" />
<TextView
android:id="@+id/cellViewTextView"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_alignParentLeft="true"
android:layout_below="@+id/nameTextView"
android:layout_marginLeft="16dp"
android:layout_marginTop="23dp"
android:text="@string/cell_phone" />
<TextView
android:id="@+id/workViewTextView"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_alignLeft="@+id/cellViewTextView"
android:layout_below="@+id/cellViewTextView"
android:layout_marginTop="16dp"
android:text="@string/work_phone" />
<TextView
android:id="@+id/emailViewTextView"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_alignLeft="@+id/workViewTextView"
android:layout_below="@+id/workViewTextView"
android:layout_marginTop="14dp"
android:text="@string/email" />
<TextView
android:id="@+id/workDisplayTextView"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_alignBottom="@+id/workViewTextView"
android:layout_alignLeft="@+id/cellDisplayTextView"
android:text="TextView" />
<TextView
android:id="@+id/cellDisplayTextView"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_alignBaseline="@+id/cellViewTextView"
android:layout_alignBottom="@+id/cellViewTextView"
android:layout_alignLeft="@+id/nameTextView"
android:layout_marginLeft="63dp"
android:text="TextView" />
<TextView
android:id="@+id/emailDisplayTextView"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_alignBaseline="@+id/emailViewTextView"
android:layout_alignBottom="@+id/emailViewTextView"
android:layout_alignLeft="@+id/workDisplayTextView"
android:text="TextView" />
<ListView
android:id="@+id/addressListView"
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:layout_alignParentRight="true"
android:layout_below="@+id/emailViewTextView"
android:layout_marginTop="16dp" >
</ListView>
</RelativeLayout>
这是地址作为 ListView 项的 XML
<?xml version="1.0" encoding="utf-8"?>
<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
android:layout_width="match_parent"
android:layout_height="match_parent"
android:orientation="vertical" >
<TextView
android:id="@+id/addressNameTextView"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_alignParentLeft="true"
android:layout_alignParentTop="true"
android:layout_marginLeft="15dp"
android:layout_marginTop="16dp"
android:text="Medium Text"
android:textAppearance="?android:attr/textAppearanceMedium" />
<TextView
android:id="@+id/addressStreetTextView"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_alignLeft="@+id/addressNameTextView"
android:layout_below="@+id/addressNameTextView"
android:layout_marginTop="16dp"
android:text="@string/street_text_view" />
<TextView
android:id="@+id/addressNumberTextView"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_alignLeft="@+id/addressStreetTextView"
android:layout_below="@+id/addressStreetTextView"
android:layout_marginTop="17dp"
android:text="@string/addres_number_text_view" />
<TextView
android:id="@+id/addressStateTextView"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_alignLeft="@+id/addressCityTextView"
android:layout_below="@+id/addressCityTextView"
android:layout_marginTop="14dp"
android:text="@string/state_text_view" />
<TextView
android:id="@+id/addressZipTextView"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_alignLeft="@+id/addressStateTextView"
android:layout_below="@+id/addressStateTextView"
android:layout_marginTop="14dp"
android:text="@string/zip_code_text_view" />
<TextView
android:id="@+id/addressCityTextView"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_alignLeft="@+id/addressNumberTextView"
android:layout_below="@+id/addressNumberTextView"
android:layout_marginTop="15dp"
android:text="@string/city_text_view" />
<TextView
android:id="@+id/stateDisplayTextView"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_alignBottom="@+id/addressStateTextView"
android:layout_alignRight="@+id/cityDisplayTextView"
android:text="TextView" />
<TextView
android:id="@+id/zipDisplayTextView"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_alignBottom="@+id/addressZipTextView"
android:layout_alignLeft="@+id/stateDisplayTextView"
android:text="TextView" />
<TextView
android:id="@+id/cityDisplayTextView"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_above="@+id/addressStateTextView"
android:layout_alignLeft="@+id/numberDisplayTextView"
android:text="TextView" />
<TextView
android:id="@+id/streetDisplayTextView"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_above="@+id/addressNumberTextView"
android:layout_marginLeft="29dp"
android:layout_toRightOf="@+id/addressNameTextView"
android:text="TextView" />
<TextView
android:id="@+id/numberDisplayTextView"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_above="@+id/addressCityTextView"
android:layout_alignLeft="@+id/streetDisplayTextView"
android:text="TextView" />
</RelativeLayout>
最后这就是给我 LOGCAT 的东西
04-03 02:27:03.566: E/AndroidRuntime(1930): FATAL EXCEPTION: main
04-03 02:27:03.566: E/AndroidRuntime(1930): Process: com.example.contactlist, PID: 1930
04-03 02:27:03.566: E/AndroidRuntime(1930): java.lang.NullPointerException
04-03 02:27:03.566: E/AndroidRuntime(1930): at edu.uprm.ece.icom4035.activities.ViewContactActivity$AddressListAdapter.getView(ViewContactA ctivity.java:112)
04-03 02:27:03.566: E/AndroidRuntime(1930): at android.widget.AbsListView.obtainView(AbsListView.java:2263)
04-03 02:27:03.566: E/AndroidRuntime(1930): at android.widget.ListView.measureHeightOfChildren(ListView.java:1263)
04-03 02:27:03.566: E/AndroidRuntime(1930): at android.widget.ListView.onMeasure(ListView.java:1175)
04-03 02:27:03.566: E/AndroidRuntime(1930): at android.view.View.measure(View.java:16497)
04-03 02:27:03.566: E/AndroidRuntime(1930): at android.widget.RelativeLayout.measureChild(RelativeLayout.java:689)
04-03 02:27:03.566: E/AndroidRuntime(1930): at android.widget.RelativeLayout.onMeasure(RelativeLayout.java:473)
04-03 02:27:03.566: E/AndroidRuntime(1930): at android.view.View.measure(View.java:16497)
04-03 02:27:03.566: E/AndroidRuntime(1930): at android.view.ViewGroup.measureChildWithMargins(ViewGroup.java:5125)
04-03 02:27:03.566: E/AndroidRuntime(1930): at android.widget.FrameLayout.onMeasure(FrameLayout.java:310)
04-03 02:27:03.566: E/AndroidRuntime(1930): at android.view.View.measure(View.java:16497)
04-03 02:27:03.566: E/AndroidRuntime(1930): at android.view.ViewGroup.measureChildWithMargins(ViewGroup.java:5125)
04-03 02:27:03.566: E/AndroidRuntime(1930): at com.android.internal.widget.ActionBarOverlayLayout.onMeasure(ActionBarOverlayLayout.java:327 )
04-03 02:27:03.566: E/AndroidRuntime(1930): at android.view.View.measure(View.java:16497)
04-03 02:27:03.566: E/AndroidRuntime(1930): at android.view.ViewGroup.measureChildWithMargins(ViewGroup.java:5125)
04-03 02:27:03.566: E/AndroidRuntime(1930): at android.widget.FrameLayout.onMeasure(FrameLayout.java:310)
04-03 02:27:03.566: E/AndroidRuntime(1930): at com.android.internal.policy.impl.PhoneWindow$DecorView.onMeasure(PhoneWindow.java:2291)
04-03 02:27:03.566: E/AndroidRuntime(1930): at android.view.View.measure(View.java:16497)
04-03 02:27:03.566: E/AndroidRuntime(1930): at android.view.ViewRootImpl.performMeasure(ViewRootImpl.java:1916)
04-03 02:27:03.566: E/AndroidRuntime(1930): at android.view.ViewRootImpl.measureHierarchy(ViewRootImpl.java:1113)
04-03 02:27:03.566: E/AndroidRuntime(1930): at android.view.ViewRootImpl.performTraversals(ViewRootImpl.java:1295)
04-03 02:27:03.566: E/AndroidRuntime(1930): at android.view.ViewRootImpl.doTraversal(ViewRootImpl.java:1000)
04-03 02:27:03.566: E/AndroidRuntime(1930): at android.view.ViewRootImpl$TraversalRunnable.run(ViewRootImpl.java:5670)
04-03 02:27:03.566: E/AndroidRuntime(1930): at android.view.Choreographer$CallbackRecord.run(Choreographer.java:761)
04-03 02:27:03.566: E/AndroidRuntime(1930): at android.view.Choreographer.doCallbacks(Choreographer.java:574)
04-03 02:27:03.566: E/AndroidRuntime(1930): at android.view.Choreographer.doFrame(Choreographer.java:544)
04-03 02:27:03.566: E/AndroidRuntime(1930): at android.view.Choreographer$FrameDisplayEventReceiver.run(Choreographer.java:747)
04-03 02:27:03.566: E/AndroidRuntime(1930): at android.os.Handler.handleCallback(Handler.java:733)
04-03 02:27:03.566: E/AndroidRuntime(1930): at android.os.Handler.dispatchMessage(Handler.java:95)
04-03 02:27:03.566: E/AndroidRuntime(1930): at android.os.Looper.loop(Looper.java:136)
04-03 02:27:03.566: E/AndroidRuntime(1930): at android.app.ActivityThread.main(ActivityThread.java:5017)
04-03 02:27:03.566: E/AndroidRuntime(1930): at java.lang.reflect.Method.invokeNative(Native Method)
04-03 02:27:03.566: E/AndroidRuntime(1930): at java.lang.reflect.Method.invoke(Method.java:515)
04-03 02:27:03.566: E/AndroidRuntime(1930): at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:779)
04-03 02:27:03.566: E/AndroidRuntime(1930): at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:595)
04-03 02:27:03.566: E/AndroidRuntime(1930): at dalvik.system.NativeStart.main(Native Method)
我已尝试解决该问题，但我不太了解原木猫向我提供的测量高度消息。
提前致谢
最佳答案
在 getView 中，您必须使用膨胀 View 来检索行项目。对于 getView 中的每个 findViewById，从 findViewById 更改为 view.findViewById。例如
TextView addressName = (TextView) findViewById(R.id.addressNameTextView);
addressName.setText(address.getAddressName());
至
TextView addressName = (TextView) view.findViewById(R.id.addressNameTextView);
addressName.setText(address.getAddressName());
关于java - 设置 ListView 元素的文本会使应用程序崩溃，测量 child 高度时出现 java 空指针异常，我们在Stack Overflow上找到一个类似的问题： https://stackoverflow.com/questions/22830362/