我希望你能帮我解决这个错误。
我想将一个活动与一个按钮相关联，但我在logcat中有这个错误（已更新）。
02-17 18:04:27.033: D/AndroidRuntime(1850): Shutting down VM
02-17 18:04:27.034: E/AndroidRuntime(1850): FATAL EXCEPTION: main
02-17 18:04:27.034: E/AndroidRuntime(1850): Process: com.cm.georganizer, PID: 1850
02-17 18:04:27.034: E/AndroidRuntime(1850): java.lang.RuntimeException: Unable to start activity ComponentInfo{com.cm.georganizer/com.cm.georganizer.MainActivity}: java.lang.NullPointerException: Attempt to invoke virtual method 'void android.widget.Button.setOnClickListener(android.view.View$OnClickListener)' on a null object reference
02-17 18:04:27.034: E/AndroidRuntime(1850): at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2298)
02-17 18:04:27.034: E/AndroidRuntime(1850): at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2360)
02-17 18:04:27.034: E/AndroidRuntime(1850): at android.app.ActivityThread.access$800(ActivityThread.java:144)
02-17 18:04:27.034: E/AndroidRuntime(1850): at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1278)
02-17 18:04:27.034: E/AndroidRuntime(1850): at android.os.Handler.dispatchMessage(Handler.java:102)
02-17 18:04:27.034: E/AndroidRuntime(1850): at android.os.Looper.loop(Looper.java:135)
02-17 18:04:27.034: E/AndroidRuntime(1850): at android.app.ActivityThread.main(ActivityThread.java:5221)
02-17 18:04:27.034: E/AndroidRuntime(1850): at java.lang.reflect.Method.invoke(Native Method)
02-17 18:04:27.034: E/AndroidRuntime(1850): at java.lang.reflect.Method.invoke(Method.java:372)
02-17 18:04:27.034: E/AndroidRuntime(1850): at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:899)
02-17 18:04:27.034: E/AndroidRuntime(1850): at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:694)
02-17 18:04:27.034: E/AndroidRuntime(1850): Caused by: java.lang.NullPointerException: Attempt to invoke virtual method 'void android.widget.Button.setOnClickListener(android.view.View$OnClickListener)' on a null object reference
02-17 18:04:27.034: E/AndroidRuntime(1850): at com.cm.georganizer.MainActivity.onCreate(MainActivity.java:47)
02-17 18:04:27.034: E/AndroidRuntime(1850): at android.app.Activity.performCreate(Activity.java:5933)
02-17 18:04:27.034: E/AndroidRuntime(1850): at android.app.Instrumentation.callActivityOnCreate(Instrumentation.java:1105)
02-17 18:04:27.034: E/AndroidRuntime(1850): at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2251)
02-17 18:04:27.034: E/AndroidRuntime(1850): ... 10 more
02-17 18:09:27.363: I/Process(1850): Sending signal. PID: 1850 SIG: 9
这是我的MainActivity（已更新）
import android.content.Intent;
import android.os.Bundle;
import android.support.v4.app.Fragment;
import android.support.v4.app.FragmentManager;
import android.util.SparseIntArray;
import android.view.Menu;
import android.view.View;
import android.widget.Toast;
import android.database.Cursor;
import android.support.v7.app.ActionBarActivity;
import android.view.View.OnClickListener;
import android.widget.AdapterView;
import android.widget.AdapterView.OnItemClickListener;
import android.widget.Button;
import android.widget.ListView;
import android.widget.SimpleCursorAdapter;
import android.widget.TextView;
import java.util.ArrayList;
import java.util.List;
import br.liveo.interfaces.NavigationLiveoListener;
import br.liveo.navigationliveo.NavigationLiveo;
public class MainActivity extends NavigationLiveo implements NavigationLiveoListener {
Button btnAgregarMiembro;
ListView lista;
SQLControlador dbconeccion;
TextView tv_miemID, tv_miemNombre;
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.fragment_main);
dbconeccion = new SQLControlador(this);
dbconeccion.abrirBaseDeDatos();
btnAgregarMiembro = (Button) findViewById(R.id.btnAgregarMiembro);
lista = (ListView) findViewById(R.id.listViewMiembros);
//acción del boton agregar miembro
btnAgregarMiembro.setOnClickListener(new OnClickListener() {
@Override
public void onClick(View v) {
Intent iagregar = new Intent(MainActivity.this, AgregarMiembro.class);
startActivity(iagregar);
}
});
// Tomar los datos desde la base de datos para poner en el curso y después en el adapter
Cursor cursor = dbconeccion.leerDatos();
String[] from = new String[] {
DBhelper.MIEMBRO_ID,
DBhelper.MIEMBRO_NOMBRE
};
int[] to = new int[] {
R.id.miembro_id,
R.id.miembro_nombre
};
SimpleCursorAdapter adapter = new SimpleCursorAdapter(
MainActivity.this, R.layout.formato_fila, cursor, from, to);
adapter.notifyDataSetChanged();
lista.setAdapter(adapter);
// acción cuando hacemos click en item para poder modificarlo o eliminarlo
lista.setOnItemClickListener(new OnItemClickListener() {
@Override
public void onItemClick(AdapterView parent, View view, int position, long id) {
tv_miemID = (TextView) view.findViewById(R.id.miembro_id);
tv_miemNombre = (TextView) view.findViewById(R.id.miembro_nombre);
String aux_miembroId = tv_miemID.getText().toString();
String aux_miembroNombre = tv_miemNombre.getText().toString();
Intent modify_intent = new Intent(getApplicationContext(), ModificarMiembro.class);
modify_intent.putExtra("miembroId", aux_miembroId);
modify_intent.putExtra("miembroNombre", aux_miembroNombre);
startActivity(modify_intent);
}
});
} //termina el onCreate
public List<String> mListNameItem;
@Override
public void onUserInformation() {
//User information here
//this.mUserName.setText("User");
//this.mUserEmail.setText("rudsonlive@gmail.com");
//this.mUserPhoto.setImageResource(R.drawable.ic_rudsonlive);
this.mUserBackground.setImageResource(R.drawable.ic_app_background);
}
@Override
public void onInt(Bundle savedInstanceState) {
//Creation of the list items is here
// set listener {required}
this.setNavigationListener(this);
//First item of the position selected from the list
this.setDefaultStartPositionNavigation(0);
// name of the list items
mListNameItem = new ArrayList<>();
mListNameItem.add(0, getString(R.string.index));
mListNameItem.add(1, getString(R.string.add_event));
// icons list items
List<Integer> mListIconItem = new ArrayList<>();
mListIconItem.add(0, R.drawable.ic_inbox_black_24dp);
mListIconItem.add(1, R.drawable.ic_star_black_24dp); //Item no icon set 0
//{optional} - Among the names there is some subheader, you must indicate it here
List<Integer> mListHeaderItem = new ArrayList<>();
mListHeaderItem.add(4);
//{optional} - Among the names there is any item counter, you must indicate it (position) and the value here
SparseIntArray mSparseCounterItem = new SparseIntArray(); //indicate all items that have a counter
mSparseCounterItem.put(0, 0);
mSparseCounterItem.put(1, 0);
//If not please use the FooterDrawer use the setFooterVisible(boolean visible) method with value false
//this.setFooterInformationDrawer(R.string.settings, R.drawable.ic_settings_black_24dp);
this.setNavigationAdapter(mListNameItem, mListIconItem, mListHeaderItem, mSparseCounterItem);
}
@Override
public void onItemClickNavigation(int position, int layoutContainerId) {
FragmentManager mFragmentManager = getSupportFragmentManager();
Fragment mFragment = new FragmentMain().newInstance(mListNameItem.get(position));
switch (position) {
case 0:
mFragment = new FragmentMain().newInstance(mListNameItem.get(position));
break;
case 1:
mFragment = new FragmentEvent().newInstance(mListNameItem.get(position));
break;
}
if (mFragment != null){
mFragmentManager.beginTransaction().replace(layoutContainerId, mFragment).commit();
}
}
@Override
public void onPrepareOptionsMenuNavigation(Menu menu, int position, boolean visible) {
//hide the menu when the navigation is opens
switch (position) {
case 0:
menu.findItem(R.id.menu_add).setVisible(!visible);
menu.findItem(R.id.menu_search).setVisible(!visible);
break;
case 1:
menu.findItem(R.id.menu_add).setVisible(!visible);
menu.findItem(R.id.menu_search).setVisible(!visible);
break;
}
}
@Override
public void onClickUserPhotoNavigation(View v) {
//user photo onClick
Toast.makeText(this, R.string.open_user_profile, Toast.LENGTH_SHORT).show();
}
@Override
public void onClickFooterItemNavigation(View v) {
//footer onClick
startActivity(new Intent(this, SettingsActivity.class));
}
}
fragment_main.xml
<?xml version="1.0" encoding="utf-8"?>
<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
android:layout_width="fill_parent"
android:layout_height="fill_parent">
<ImageView
android:id="@+id/imgLiveo"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_alignParentTop="true"
android:layout_centerHorizontal="true"
android:contentDescription="@string/clear"
android:src="@drawable/logo" />
<TextView
android:id="@+id/txtTitle"
android:layout_width="fill_parent"
android:layout_height="wrap_content"
android:layout_below="@+id/imgLiveo"
android:gravity="center"
android:layout_marginTop="16dp"
android:text="@string/clear"
android:textAppearance="?android:attr/textAppearanceMedium" />
<Button
android:id="@+id/btnAgregarMiembro"
android:layout_width="fill_parent"
android:layout_below="@+id/txtTitle"
android:layout_height="wrap_content"
android:text="Agregar miembro" />
<ListView
android:id="@+id/listViewMiembros"
android:layout_width="match_parent"
android:layout_below="@+id/btnAgregarMiembro"
android:layout_height="wrap_content"
android:dividerHeight="2dp" >
</ListView>
</RelativeLayout>
我已多次尝试修复它但不起作用
事先非常感谢你的帮助