我正在尝试为我的项目中的特定组（比如第一个）动态添加记录。 这是我想出的代码，我在添加记录时插入。所以当我添加一条记录时，会创建一个新的孩子：
public class addshare extends Activity{
DBAdapter db = new DBAdapter(this);
MyCustomAdapter c=new MyCustomAdapter();
private ExpandableListView mExpandableList;
public void addshare(){}
@Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.add);
}
public void addingshare(View v)
{
Log.d("test", "adding");
//get data from form
//EditText intypeid = (EditText)findViewById(R.id.intypeid);
EditText sharename= (EditText)findViewById(R.id.sharename);
EditText shareid = (EditText)findViewById(R.id.shareid);
EditText purpri = (EditText)findViewById(R.id.purpri);
EditText sharepri = (EditText)findViewById(R.id.sharepri);
EditText shareno = (EditText)findViewById(R.id.shareno);
EditText purdate = (EditText)findViewById(R.id.purdate);
EditText purplace = (EditText)findViewById(R.id.purplace);
EditText purcon = (EditText)findViewById(R.id.purcon);
Float totalinvestment=0F,currmarketvalue=0F;
String sname=sharename.getText().toString();
String s1=sharepri.getText().toString();
Float n1=Float.parseFloat(s1);
String s2=purpri.getText().toString();
Float n2=Float.parseFloat(s2);
// shares_equities s=new shares_equities( sname);
String s3=shareno.getText().toString();
Integer i1=Integer.parseInt(s3);
db.open();
long id = db.addRecord(sname, shareid.getText().toString(),
n2,n1,i1, purdate.getText().toString(),purplace.getText().toString(),purcon.getText().toString()
,totalinvestment,currmarketvalue);
//COMMENTED BELOW AS IT GENERATES THE EXCEPTION
/* mExpandableList= (ExpandableListView) this.findViewById(R.id.expandable_list);
ExpandableListAdapter adapter = (ExpandableListAdapter) mExpandableList.getExpandableListAdapter();
ArrayList<String> arrayChildren = new ArrayList<String>();
ArrayList<parent> arrayParents = new ArrayList<parent>();
parent parent1=new parent();
parent parent2=new parent();
parent parent3=new parent();
parent parent4=new parent();
parent1 = ((parent)adapter.getGroup(0));
arrayChildren=parent1.getArrayChildren();
arrayChildren.add("share4");
parent1.setArrayChildren(arrayChildren);
arrayParents.add(parent1);
parent2 = ((parent)adapter.getGroup(1));
arrayParents.add(parent2);
parent3 = ((parent)adapter.getGroup(2));
arrayParents.add(parent3);
parent4 = ((parent)adapter.getGroup(3));
arrayParents.add(parent4);
mExpandableList.setAdapter(new MyCustomAdapter(addshare.this,arrayParents));
*/
db.close();
sharename.setText("");
shareid.setText("");
purpri.setText("");
sharepri.setText("");
shareno.setText("");
purdate.setText("");
purplace.setText("");
purcon.setText("");
Toast.makeText(addshare.this,"share record Added", Toast.LENGTH_LONG).show();
Intent i = new Intent(this, MainActivity.class);
startActivity(i);
}
public void viewAssignments(View v)
{
Intent i = new Intent(this, MainActivity.class);
startActivity(i);
}
}
上面的代码在我添加记录时出现此错误： logcat的：
06-18 22:55:12.632: E/AndroidRuntime(681): FATAL EXCEPTION: main
06-18 22:55:12.632: E/AndroidRuntime(681): java.lang.IllegalStateException: Could not execute method of the activity
06-18 22:55:12.632: E/AndroidRuntime(681): at android.view.View$1.onClick(View.java:3039)
06-18 22:55:12.632: E/AndroidRuntime(681): at android.view.View.performClick(View.java:3480)
06-18 22:55:12.632: E/AndroidRuntime(681): at android.view.View$PerformClick.run(View.java:13983)
06-18 22:55:12.632: E/AndroidRuntime(681): at android.os.Handler.handleCallback(Handler.java:605)
06-18 22:55:12.632: E/AndroidRuntime(681): at android.os.Handler.dispatc hMessage(Handler.java:92)
06-18 22:55:12.632: E/AndroidRuntime(681): at android.os.Looper.loop(Looper.java:137)
06-18 22:55:12.632: E/AndroidRuntime(681): at android.app.ActivityThread.main(ActivityThread.java:4340)
06-18 22:55:12.632: E/AndroidRuntime(681): at java.lang.reflect.Method.invokeNative(Native Method)
06-18 22:55:12.632: E/AndroidRuntime(681): at java.lang.reflect.Method.invoke(Method.java:511)
06-18 22:55:12.632: E/AndroidRuntime(681): at com .android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:784)
06-18 22:55:12.632: E/AndroidRuntime(681): at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:551)
06-18 22:55:12.632: E/AndroidRuntime(681): at dalvik.system.NativeStart.main(Native Method)
06-18 22:55:12.632: E/AndroidRuntime(681): Caused by: java.lang.reflect.InvocationTargetException
06-18 22:55:12.632: E/AndroidRuntime(681): at java.lang.reflect.Method.invokeNative(Native Method)
06-18 22:55:12.632: E/AndroidRuntime(681): at java.lang.reflect.Method.invoke(Method.java:511)
06-18 22:55:12.632: E/AndroidRuntime(681): at android.view.View$1.onClick(View.java:3034)
06-18 22:55:12.632: E/AndroidRuntime(681): ... 11 more
06-18 22:55:12.632: E/AndroidRuntime(681): Caused by: java.lang.NullPointerException
06-18 22:55:12.632: E/AndroidRuntime(681): at com.example.moolah.addshare.addingshare(addshare.java:58)
06-18 22:55:12.632: E/AndroidRuntime(681): ... 14 more
可扩展列表xml（主要）
<?xml version="1.0" encoding="utf-8"?>
<ScrollView xmlns:android="http://schemas.android.com/apk/res/android"
android:layout_width="fill_parent"
android:layout_height="fill_parent"
>
<LinearLayout
android:layout_width="fill_parent"
android:layout_height="wrap_content"
android:orientation="vertical" >
...
<ExpandableListView
android:id="@+id/expandable_list"
android:layout_width="fill_parent"
android:layout_height="400dp"
android:layout_weight="2900208.75"
android:cacheColorHint="#00000000"
android:listSelector="@android:color/transparent"
android:transcriptMode="disabled" />
<Button
android:id="@+id/addnew"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_gravity="center"
android:layout_margin="5dp"
android:text="ADD NEW"
android:onClick="sendMessage_addrecord" />
</LinearLayout>
答案 0 :(得分：1)
mExpandableList为空，因此this.findViewById(R.id.expandable_list)无法找到该视图。