适配器android应用程序

Question

我正在开发一个android应用程序，我正在测试一些代码，看它是如何工作的，但有一些错误，我尝试解决它们，但我不能。我是移动开发的新手，我必须制定待办事项列表。问题是我不适合使用适配器和listView，所以我试图理解它们。

Java代码的

 package com.example.test; 

import android.os.Bundle; 
import android.app.Activity; 
import android.view.Menu; 
import android.widget.AdapterView; 
import android.widget.ArrayAdapter; 
import android.widget.ListView; 

public class SimpleListItem1Activity extends Activity { 

    @Override 
    protected void onCreate(Bundle savedInstanceState) { 
     super.onCreate(savedInstanceState); 
     setContentView(R.layout.simple_list_item1); 
     ListView listView = (ListView) findViewById(R.id.mylist); 

     ArrayAdapter<String> adapter = new ArrayAdapter<String>(this, 
      android.R.layout.simple_list_item_1, android.R.id.text1, values); 

      listView.setAdapter(adapter); 
    } 

    @Override 
    public boolean onCreateOptionsMenu(Menu menu) { 
     // Inflate the menu; this adds items to the action bar if it is present. 
     getMenuInflater().inflate(R.menu.simple_list_item1, menu); 
     return true; } 

    ListView listView = (ListView) findViewById(R.id.mylist); 
    String[] values = new String[] { "Android", "iPhone", "WindowsMobile", 
     "Blackberry", "WebOS", "Ubuntu", "Windows7", "Max OS X", 
     "Linux", "OS/2" }; 

    // Define a new Adapter 
    // First parameter - Context 
    // Second parameter - Layout for the row 
    // Third parameter - ID of the TextView to which the data is written 
    // Forth - the Array of data 

    ArrayAdapter<String> adapter = new ArrayAdapter<String>(this, 
     android.R.layout.simple_list_item_1, android.R.id.text1, values); 



} 

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" 
    android:orientation="vertical" > 

    <ListView 
     android:id="@+id/mylist" 
     android:layout_width="match_parent" 
     android:layout_height="wrap_content" > 
    </ListView> 

</LinearLayout> 

logcat的

03-14 14:57:07.643: E/AndroidRuntime(773):  ... 11 more 
[2013-03-14 17:54:54 - test] ------------------------------ 
[2013-03-14 17:54:54 - test] Android Launch! 
[2013-03-14 17:54:54 - test] adb is running normally. 
[2013-03-14 17:54:54 - test] Performing com.example.test.SimpleListItem1Activity activity launch 
[2013-03-14 17:54:54 - test] Automatic Target Mode: launching new emulator with compatible AVD 'AVD_for_Nexus_S_by_Google' 
[2013-03-14 17:54:54 - test] Launching a new emulator with Virtual Device 'AVD_for_Nexus_S_by_Google' 
[2013-03-14 17:55:08 - Emulator] emulator: warning: opening audio input failed 
[2013-03-14 17:55:08 - Emulator] 
[2013-03-14 17:55:08 - test] New emulator found: emulator-5554 
[2013-03-14 17:55:08 - test] Waiting for HOME ('android.process.acore') to be launched... 
[2013-03-14 17:56:06 - test] HOME is up on device 'emulator-5554' 
[2013-03-14 17:56:06 - test] Uploading test.apk onto device 'emulator-5554' 
[2013-03-14 17:56:07 - test] Installing test.apk... 
[2013-03-14 17:57:06 - test] Success! 
[2013-03-14 17:57:06 - test] Starting activity com.example.test.SimpleListItem1Activity on device emulator-5554 
[2013-03-14 17:57:09 - test] ActivityManager: Starting: Intent { act=android.intent.action.MAIN cat=[android.intent.category.LAUNCHER] cmp=com.example.test/.SimpleListItem1Activity } 
[2013-03-14 18:07:20 - test] ------------------------------ 
[2013-03-14 18:07:20 - test] Android Launch! 
[2013-03-14 18:07:20 - test] adb is running normally. 
[2013-03-14 18:07:20 - test] Performing com.example.test.SimpleListItem1Activity activity launch 
[2013-03-14 18:07:20 - test] Automatic Target Mode: launching new emulator with compatible AVD 'AVD_for_Nexus_S_by_Google' 
[2013-03-14 18:07:20 - test] Launching a new emulator with Virtual Device 'AVD_for_Nexus_S_by_Google' 
[2013-03-14 18:07:23 - Emulator] emulator: warning: opening audio input failed 
[2013-03-14 18:07:23 - Emulator] 
[2013-03-14 18:07:23 - test] New emulator found: emulator-5554 
[2013-03-14 18:07:23 - test] Waiting for HOME ('android.process.acore') to be launched... 
[2013-03-14 18:08:21 - test] HOME is up on device 'emulator-5554' 
[2013-03-14 18:08:21 - test] Uploading test.apk onto device 'emulator-5554' 
[2013-03-14 18:08:21 - test] Installing test.apk... 
[2013-03-14 18:10:25 - test] Failed to install test.apk on device 'emulator-5554! 
[2013-03-14 18:10:25 - test] (null) 
[2013-03-14 18:10:25 - test] Launch canceled! 

Answer 1

编辑：

它应该是这样的

public class SimpleListItem1Activity extends Activity { 
String[] values = new String[] { "Android", "iPhone", "WindowsMobile", 
     "Blackberry", "WebOS", "Ubuntu", "Windows7", "Max OS X", 
     "Linux", "OS/2" }; 

    @Override 
    protected void onCreate(Bundle savedInstanceState) { 
     super.onCreate(savedInstanceState); 
     setContentView(R.layout.simple_list_item1); 
     ListView listView = (ListView) findViewById(R.id.mylist); 

     ArrayAdapter<String> adapter = new ArrayAdapter<String>(this, 
      android.R.layout.simple_list_item_1, values); 
      listView.setAdapter(adapter); 
    } 

    @Override 
    public boolean onCreateOptionsMenu(Menu menu) { 
     // Inflate the menu; this adds items to the action bar if it is present. 
     getMenuInflater().inflate(R.menu.simple_list_item1, menu); 
     return true; 
} 

} 

---

 ListView listView = (ListView) findViewById(R.id.mylist); 

    ArrayAdapter<String> adapter = new ArrayAdapter<String>(this, 
     android.R.layout.simple_list_item_1, android.R.id.text1, values); 

     listView.setAdapter(adapter); 

此代码应该是有内部的onCreate，但你已经宣布它身边，让你列表视图总是空，直到你设置的内容查看你不会得到的视图。

将设置内容查看在OnCreate中