Java 应用程序未启动
我是android编程新手,最近开始制作一个实践应用程序 虽然代码是无错误的,但在模拟器中启动时,应用程序会显示“不幸的是PocketMoney已经停止” 日志:Java 应用程序未启动,java,android,eclipse,nullpointerexception,android-activity,Java,Android,Eclipse,Nullpointerexception,Android Activity,我是android编程新手,最近开始制作一个实践应用程序 虽然代码是无错误的,但在模拟器中启动时,应用程序会显示“不幸的是PocketMoney已经停止” 日志: FATAL EXCEPTION: main java.lang.RuntimeException: Unable to instantiate activity ComponentInfo{com.example.pocketmoney/com.example.pocketmoney.PocketMoney}: java.
FATAL EXCEPTION: main
java.lang.RuntimeException: Unable to instantiate activity
ComponentInfo{com.example.pocketmoney/com.example.pocketmoney.PocketMoney}:
java.lang.NullPointerException
MainActivity.java
public class PocketMoney extends Activity {
final String TAG="pocketmoney";
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.main);
Log.i(TAG, "Now in onCreate() ");
final Button NonMeal_button=(Button)findViewById(R.id.nonmeal_button);
final Button Meal_button=(Button)findViewById(R.id.meal_button);
if(checkPocketValues()==false)
{
startSettings_Activity();
}
Meal_button.setOnClickListener(new OnClickListener() {
//listener for Meal_Button
@Override
public void onClick(View arg0) {
// TODO Auto-generated method stub
startMeal_Money_Activity();
}
});
NonMeal_button.setOnClickListener(new OnClickListener() {
//Listener for NonMeal_button
@Override
public void onClick(View v) {
// TODO Auto-generated method stub
startNonMeal_Money_Activity();
}
});
}
void startSettings_Activity(){
//to start Settings_Activity
startActivity(new Intent(getApplicationContext(),Settings_Activity.class));
}
void startMeal_Money_Activity()
{
startActivity(new Intent(this,Meal_Money_Activity.class));
}
void startNonMeal_Money_Activity()
{
startActivity(new Intent(this,NonMeal_Money_Activity.class));
}
boolean checkPocketValues()
{
//to check if Pocket values are filled
boolean SettingsFilled=true;
Settings_Activity check=new Settings_Activity();
if((check.preferences.getFloat(check.MealMoney,0)==0)&&check.preferences.getFloat(check.NonMealMoney, 0)==0)
{
SettingsFilled=false;
}
return SettingsFilled;
}
public void onStop()
{
Log.i(TAG,"now onStop method is called ");
}
@Override
public boolean onCreateOptionsMenu(Menu menu) {
// Inflate the menu; this adds items to the action bar if it is present.
getMenuInflater().inflate(R.menu.pocket_money, menu);
return true;
}
}
你有
Settings_Activity check=new Settings_Activity(); // wrong
看起来Settings\u Activity
是一个活动类,您正在实例化同一个活动类,这是错误的
引用拉格哈夫
通过将一个活动视为一个普通的Java类,您将得到一个null
上下文由于活动中的大多数方法都是在其上下文中调用的,因此
将获得空指针异常,这就是应用程序崩溃的原因
你有这个吗
(check.preferences.getFloat(check.MealMoney,0)
因此,崩溃可能是由于这个Settings\u Activity check=new Settings\u Activity()代码>
替换为:
void startSettings_Activity(){
//to start Settings_Activity
startActivity(new Intent(this,Settings_Activity.class));
}
发布logcat错误代码和清单文件代码您的NullPointerException
,可能在onCreate
方法中。发布完整的堆栈跟踪,并对堆栈跟踪中指定的数字行进行注释。请显示main.xml
layoutt这与崩溃无关
void startSettings_Activity(){
//to start Settings_Activity
startActivity(new Intent(this,Settings_Activity.class));
}