我正在创建一个应用程序，当按下其中一个按钮时，我需要一个活动来打开。他们都开了同样的活动。我已经检查过，它们都有正确的文件名，它们都在清单中，但是当我尝试单击按钮打开活动时，它会告诉我“不幸......已经停止了”。请帮我。这是清单：
<manifest xmlns:android="http://schemas.android.com/apk/res/android" package="com.apps.testp">
<uses-sdk
android:minSdkVersion="8"
android:targetSdkVersion="8" />
<application
android:allowBackup="true"
android:icon="@drawable/ic_launcher"
android:label="@string/app_name"
android:theme="@style/AppTheme" >
<activity
android:name="com.apps.testp.MainActivityWithButtons"
android:label="@string/app_name" >
<intent-filter>
<action android:name="android.intent.action.MAIN" />
<category android:name="android.intent.category.LAUNCHER" />
</intent-filter>
</activity>
<activity
android:name="com.apps.testp.LocationSelectFromAlertButtons"
android:label="@string/title_activity_location_select_from_alert_buttons" >
</activity>
</application>
这是MainActivityWithButtons.java：
package com.apps.testp;
import android.support.v7.app.ActionBarActivity;
import android.content.Intent;
import android.os.Bundle;
import android.view.Menu;
import android.view.MenuItem;
import android.view.View;
import android.widget.Button;
@SuppressWarnings("deprecation")
public class MainActivityWithButtons extends ActionBarActivity {
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main_activity_with_buttons);
Button breakIn=(Button)findViewById(R.id.houseBreakIn);
Button robbery=(Button)findViewById(R.id.storeRobbery);
Button car=(Button)findViewById(R.id.carTheft);
Button assaulting=(Button)findViewById(R.id.assault);
Button shots=(Button)findViewById(R.id.shotsFired);
Button fight=(Button)findViewById(R.id.fighting);
Button address=(Button)findViewById(R.id.setOrChangeAddress);
address.setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View v) {
Intent i = new Intent(MainActivityWithButtons.this, LocationSelectFromAlertButtons.class);
startActivity(i);
}
});
breakIn.setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View v) {
Intent i = new Intent(MainActivityWithButtons.this, LocationSelectFromAlertButtons.class);
startActivity(i);
}
});
robbery.setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View v) {
Intent i = new Intent(MainActivityWithButtons.this, LocationSelectFromAlertButtons.class);
startActivity(i);
}
});
car.setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View v) {
Intent i = new Intent(MainActivityWithButtons.this, LocationSelectFromAlertButtons.class);
startActivity(i);
}
});
assaulting.setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View v) {
Intent i = new Intent(MainActivityWithButtons.this, LocationSelectFromAlertButtons.class);
startActivity(i);
}
});
shots.setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View v) {
Intent i = new Intent(MainActivityWithButtons.this, LocationSelectFromAlertButtons.class);
startActivity(i);
}
});
fight.setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View v) {
Intent i = new Intent(MainActivityWithButtons.this, LocationSelectFromAlertButtons.class);
startActivity(i);
}
});
//Next Listener Goes Here
}
@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_activity_with_buttons, menu);
return true;
}
@Override
public boolean onOptionsItemSelected(MenuItem item) {
// Handle action bar item clicks here. The action bar will
// automatically handle clicks on the Home/Up button, so long
// as you specify a parent activity in AndroidManifest.xml.
int id = item.getItemId();
if (id == R.id.action_settings) {
return true;
}
return super.onOptionsItemSelected(item);
}
}
以下是我要打开的活动：
package com.apps.testp;
import android.support.v7.app.ActionBarActivity;
import android.os.Bundle;
import android.view.Menu;
import android.view.MenuItem;
import android.view.View;
import android.widget.Button;
import android.widget.EditText;
import android.widget.TextView;
@SuppressWarnings("deprecation")
public class LocationSelectFromAlertButtons extends ActionBarActivity {
DBAdapter myDB;
Button save=(Button)findViewById(R.id.saveBtn);
TextView currentAddress=(TextView)findViewById(R.id.CurrAddress);
EditText addressNew=(EditText)findViewById(R.id.tbNewAddress);
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_location_select_from_alert_buttons);
openDB();
}
private void openDB() {
myDB = new DBAdapter(this);
myDB.open();
}
@Override
protected void onDestroy() {
super.onDestroy();
closeDB();
}
private void closeDB() {
myDB.close();
}
public void saveButtonClicked(){
long newId =myDB.insertRow(LocationSelectFromAlertButtons.this.addressNew.getText().toString());
}
@Override
public boolean onCreateOptionsMenu(Menu menu) {
// Inflate the menu; this adds items to the action bar if it is present.
getMenuInflater().inflate(R.menu.location_select_from_alert_buttons,
menu);
return true;
}
@Override
public boolean onOptionsItemSelected(MenuItem item) {
// Handle action bar item clicks here. The action bar will
// automatically handle clicks on the Home/Up button, so long
// as you specify a parent activity in AndroidManifest.xml.
int id = item.getItemId();
if (id == R.id.action_settings) {
return true;
}
return super.onOptionsItemSelected(item);
}
}
所有帮助将不胜感激！ 谢谢你们
修改
logcat的：
07-18 20:01:55.572 21821-21821/com.apps.testp D/dalvikvm? Late-enabling CheckJNI
07-18 20:01:55.572 21821-21821/com.apps.testp D/dalvikvm? Try to disable coredump for pid 21821
07-18 20:01:55.903 21821-21821/com.apps.testp I/dalvikvm? Could not find method android.content.res.TypedArray.getChangingConfigurations, referenced from method android.support.v7.internal.widget.TintTypedArray.getChangingConfigurations
07-18 20:01:55.903 21821-21821/com.apps.testp W/dalvikvm? VFY: unable to resolve virtual method 411: Landroid/content/res/TypedArray;.getChangingConfigurations ()I
07-18 20:01:55.903 21821-21821/com.apps.testp D/dalvikvm? VFY: replacing opcode 0x6e at 0x0002
07-18 20:01:55.903 21821-21821/com.apps.testp I/dalvikvm? Could not find method android.content.res.TypedArray.getType, referenced from method android.support.v7.internal.widget.TintTypedArray.getType
07-18 20:01:55.903 21821-21821/com.apps.testp W/dalvikvm? VFY: unable to resolve virtual method 433: Landroid/content/res/TypedArray;.getType (I)I
07-18 20:01:55.903 21821-21821/com.apps.testp D/dalvikvm? VFY: replacing opcode 0x6e at 0x0002
07-18 20:01:56.112 21821-21821/com.apps.testp D/libEGL? loaded /vendor/lib/egl/libEGL_POWERVR_SGX544_115.so
07-18 20:01:56.143 21821-21821/com.apps.testp D/libEGL? loaded /vendor/lib/egl/libGLESv1_CM_POWERVR_SGX544_115.so
07-18 20:01:56.153 21821-21821/com.apps.testp D/libEGL? loaded /vendor/lib/egl/libGLESv2_POWERVR_SGX544_115.so
07-18 20:01:56.233 21821-21821/com.apps.testp D/OpenGLRenderer? Enabling debug mode 0
07-18 20:01:58.432 21821-21821/com.apps.testp D/AndroidRuntime? Shutting down VM
07-18 20:01:58.432 21821-21821/com.apps.testp W/dalvikvm? threadid=1: thread exiting with uncaught exception (group=0x41abae10)
07-18 20:01:58.432 21821-21821/com.apps.testp E/AndroidRuntime? FATAL EXCEPTION: main
java.lang.RuntimeException: Unable to instantiate activity ComponentInfo{com.apps.testp/com.apps.testp.LocationSelectFromAlertButtons}: java.lang.NullPointerException
at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2171)
at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2295)
at android.app.ActivityThread.access$700(ActivityThread.java:150)
at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1280)
at android.os.Handler.dispatchMessage(Handler.java:99)
at android.os.Looper.loop(Looper.java:137)
at android.app.ActivityThread.main(ActivityThread.java:5279)
at java.lang.reflect.Method.invokeNative(Native Method)
at java.lang.reflect.Method.invoke(Method.java:511)
at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:1102)
at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:869)
at dalvik.system.NativeStart.main(Native Method)
Caused by: java.lang.NullPointerException
at android.app.Activity.findViewById(Activity.java:1886)
at com.apps.testp.LocationSelectFromAlertButtons.<init>(LocationSelectFromAlertButtons.java:17)
at java.lang.Class.newInstanceImpl(Native Method)
at java.lang.Class.newInstance(Class.java:1319)
at android.app.Instrumentation.newActivity(Instrumentation.java:1071)
at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2162)
at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2295)
at android.app.ActivityThread.access$700(ActivityThread.java:150)
at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1280)
at android.os.Handler.dispatchMessage(Handler.java:99)
at android.os.Looper.loop(Looper.java:137)
at android.app.ActivityThread.main(ActivityThread.java:5279)
at java.lang.reflect.Method.invokeNative(Native Method)
at java.lang.reflect.Method.invoke(Method.java:511)
at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:1102)
at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:869)
at dalvik.system.NativeStart.main(Native Method)
答案 0 :(得分：0)
找到这个：
Button save=(Button)findViewById(R.id.saveBtn);
TextView currentAddress=(TextView)findViewById(R.id.CurrAddress);
EditText addressNew=(EditText)findViewById(R.id.tbNewAddress);
在你的setContentView之后。
答案 1 :(得分：0)
我认为问题可能在你的清单中。你还没有设置
android:parentActivityName="com.apps.testp.MainActivityWithButtons"
系统使用它来启用导航行为（用户会期望）并且我不知道您是否可以按照您的意图导航而不将其包含在清单中。
要支持旧设备，还包括：
<meta-data android:name="android.support.PARENT_ACTIVITY"
android:value="com.apps.testp.MainActivityWithButtons" />
在您的活动声明正文中。
有关详细信息，请参阅http://developer.android.com/training/basics/firstapp/starting-activity.html。
我之前已经按照developer.android.com上的指南来实现这样的功能而没有问题。
答案 2 :(得分：0)
问题在于：
Caused by: java.lang.NullPointerException
at android.app.Activity.findViewById(Activity.java:1886)
在您的活动中拥有有效的上下文之前，调用findViewById()会导致这种情况。
当您致电findViewById()时，它实际上是this.findViewById()的缩写，在您的情况下，this为空，因此为NullPointerException。
请注意，为了找到按钮，需要将正确的布局扩展到窗口中，因此您需要在setContentView()之后放置这些调用：
Button save;
TextView currentAddress;
EditText addressNew;
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_location_select_from_alert_buttons);
save = (Button)findViewById(R.id.saveBtn);
currentAddress = (TextView)findViewById(R.id.CurrAddress);
addressNew = (EditText)findViewById(R.id.tbNewAddress);
openDB();
}