nullpointerexception

问题 I've the below JSF managed bean: package com.example; import java.io.Serializable; import javax.faces.bean.ManagedBean; import org.springframework.beans.factory.annotation.Autowired; import org.springframework.stereotype.Component; @Component @ManagedBean public class Bean implements Serializable { @Autowired private SomeService someService; public void update() { someService.update(someEntity); } // ... } And the below Spring service: @Transactional @Repository public class SomeService {

问题 I've the below JSF managed bean: package com.example; import java.io.Serializable; import javax.faces.bean.ManagedBean; import org.springframework.beans.factory.annotation.Autowired; import org.springframework.stereotype.Component; @Component @ManagedBean public class Bean implements Serializable { @Autowired private SomeService someService; public void update() { someService.update(someEntity); } // ... } And the below Spring service: @Transactional @Repository public class SomeService {

问题 Consider below one : Object nothingToHold = null; System.out.println(nothingToHold); // Safely prints 'null' Here, Sysout must be expecting String. So toString() must be getting invoked on instance. So why null.toString() works awesome? Is Sysout taking care of this? EDIT : Actually I saw this weird thing with the append() of StringBuilder. So tried with Sysout. Both behave in the same way. So is that method also taking care? 回答1: PrintWriter 's println(Object) (which is the method called

问题 This question already has answers here : Null check chain vs catching NullPointerException (19 answers) Avoiding != null statements (63 answers) Closed 2 years ago . I need to check if some value is null or not. And if its not null then just set some variable to true. There is no else statement here. I got too many condition checks like this. Is there any way to handle this null checks without checking all method return values? if(country != null && country.getCity() != null && country

问题 This question already has answers here : Null check chain vs catching NullPointerException (19 answers) Avoiding != null statements (63 answers) Closed 2 years ago . I need to check if some value is null or not. And if its not null then just set some variable to true. There is no else statement here. I got too many condition checks like this. Is there any way to handle this null checks without checking all method return values? if(country != null && country.getCity() != null && country

问题 This question already has answers here : Null check chain vs catching NullPointerException (19 answers) Avoiding != null statements (63 answers) Closed 2 years ago . I need to check if some value is null or not. And if its not null then just set some variable to true. There is no else statement here. I got too many condition checks like this. Is there any way to handle this null checks without checking all method return values? if(country != null && country.getCity() != null && country

问题 When I m trying to call panel2 inside actionPerformed method, I m getting nullpointerexception. Plz help me in getting out of this silly prblm. public class PanelEventTest implements ActionListener { /** * @param args */ JFrame frame; JPanel panel1, panel2; String[] list = {"Sachin","Tarun","Vipin"}; JList jlist; JButton next; void originalFrame() { frame = new JFrame(); frame.setSize(500, 300); frame.setVisible(true); frame.setLayout(new FlowLayout()); frame.add(panel1()); frame.add(panel2()

问题 Good day! I'm implementing aChartEngine to draw charts on Android and have faced with a trouble: I receive NullPointerException when try to add created chart view to layout with addView method. chart_layout.xml: <?xml version="1.0" encoding="utf-8"?> <RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android" android:id="@+id/charts_relative_layout" android:orientation="vertical" android:layout_width="fill_parent" android:layout_height="fill_parent" > <LinearLayout android:name

问题 I am creating an android app for a restaurant that lets the waiters take the customers orders. I am using a extended list view to show the menu and have used a hashmap to populate the extended list view. When I run the app, there are no errors but the app crashes when trying to open the activity with the extended list view on it. After debugging, I found that there were null pointer exceptions causing it to crash but I'm struggling to fix it. Below is my code: Menu activity: public class Menu

问题 I have 3 activities we will call them A, B and C. A and B both have intents that send the view to C. And design on which one C came from different things happen on C's activity. I pass the data like this from A to C: Intent intent = new Intent(this, C.class); intent.putExtra("Action", "A"); startActivity(intent); Then in C's onCreate method I have something like this: Bundle extras = getIntent().getExtras(); if (extras.getString("Action").equals("A")) { //DO SOMETHING } Then I from B to C I