在java中
class C{
public void d(){
...
E.f();
...
}
}
堆栈跟踪将是
at a.b.C.d(C.java:300)
at a.b.E.f(E.java:500)
但是如果我看到类似这样的东西,我该如何处理'J9VMInternals‘类呢
at a.b.E.f(E.java:500)
...
at java.lang.J9VMInternals.initializeImpl(Native Method)
at java.lang.J9VMInternals.ini
我买了一本名为“学习Java”的新书,我正在努力解决以下问题。
它问我下面代码的类型,但是现在它说我们要用我们自己的图形类替换JLabel。HelloCompoent是他希望我创建的新图形类,它应该显示Hello Java。
import javax.swing.*;
public class Helloworld {
public static void main(String[]args){
JFrame frame = new JFrame ("Hello, Java");
JLabel label = new JLabel(
This is a login form for a slot machine game which will evoke a "NextPage" object. I don't think this LoginDemo.java code has to do anything with the error but I prefer to post the entire code. Thanks in advance..
//LoginDemo.java
import javax.swing.*;
import java.awt.*;
import java.
我有一个抽象类Entity.java和一个扩展它的类,Magician.java。每当我创建一个new Magician("Ged", 300),然后调用System.out.println(),它总是打印null(0),我不知道为什么它应该打印Ged(300)。以下是相关代码:
实体字段/构造函数:
public abstract class Entity {
protected String name;
protected int lifePoints = 0;
public Entity(String name, int lifePoints)
我知道什么时候对字段和构造函数使用关键字"this“,但我不确定它何时作为参数传递
import javax.swing.*;
import java.awt.event.*;
public class SimpleGui implements ActionListener {
JButton button;
public static void main (String[] args) {
SimpleGui gui = new SimpleGui();
gui.go();
}
pu
我正在寻找这个错误的解决方案,控制台上写的是Exception in thread "AWT-EventQueue-0" java.lang.StackOverflowError at sun.awt.Win32GraphicsConfig.getBounds(Native Method) at sun.awt.Win32GraphicsConfig.getBounds(Unknown Source) at java.awt.Window.init(Unknown Source) at java.awt.Window.<init>(U
package lab07_PrinceRalambomanarivo;
import java.awt.Color;
import javax.swing.*;
import java.util.Random;
public class ESPGame {
private String chosenColor;
public Color chooseColor(int input)
{
Color color;
switch(input)
{
case 1:
color = Color.BLUE;
我试图在GAE应用程序中使用lucene,但是,在lucene 3.1.0中,即使使用RAMDirectory (应该可以,我只有大约300个文档要索引),我在提交或关闭索引时出现错误(见下文)。线索?
Caused by: java.lang.NullPointerException
at org.apache.lucene.store.IndexOutput.writeString(IndexOutput.java:103)
at org.apache.lucene.store.IndexOutput.writeStringStringMap(IndexOutput.java:221)
a
当我想要绘制我的多边形NullPointerException对象时,我一直得到一个Pizza。我收到以下错误消息:
Exception in thread "main" java.lang.NullPointerException
at Pizza.<init>(Pizza.java:9)
at PolyDemo$PolyDemoPanel.getRandShape(PolyDemo.java:91)
at PolyDemo$PolyDemoPanel.<init>(PolyDemo.java:54)
at PolyDe
下面是我的主类:
package fast;
import java.awt.BorderLayout;
import java.awt.Color;
import java.io.IOException;
import javax.swing.JFrame;
import javax.swing.JPanel;
public class Fast {
public JFrame frame = new JFrame("Fast");
public JPanel panel = new JPanel();
public Screen screen
出现了以下异常。
The last packet sent successfully to the server was 0 milliseconds ago. The driver has not received any packets from the server.
at sun.reflect.NativeConstructorAccessorImpl.newInstance0(Native Method)
at sun.reflect.NativeConstructorAccessorImpl.newInstance(NativeConstructorAcc
我在App中有一个Java应用程序,最近我开始收到以下错误:
Unable to export to Monitering service because: GaxError RPC failed, caused by 3:One or more TimeSeries could not be written: Metrics cannot be written to gae_app. See https://cloud.google.com/monitoring/custom-metrics/creating-metrics#which-resource for a list of writ
我有两个类,名为Game.java和KeyInput.java。如何从Game.java访问int x和int y并在KeyInput.java中使用?
Game.java
public class Game extends JFrame {
int x, y;
//Constructor
public Game(){
setTitle("Game");
setSize(300, 300);
setResizable(false);
setVisible(true);
setDefaultCloseOperation(JF
我试图将代码组织到我可以在主处理类之外绘制的地方,然而,每当我尝试这样做时,我都会得到一个NullPointerExeption。 public class Processing extends PApplet {
PApplet p = new PApplet();
Screen homeScreen = new Screen(new Vector2(0, 0), p);
public static void main(String[] args) {
PApplet.runSketch(new String[]{"Processing&
我目前正在开发一个使用AWS和AWS S3的项目。我想要创建一个Lambda,它将写入S3桶中。下面是我用Java编写的lambda:
public class WriteIntoBucketHandler implements RequestHandler<SNSEvent, PutObjectResult> {
@Override
public PutObjectResult handleRequest(SNSEvent snsEvent, Context context) {
System.out.println("Connect t
不久前,我提出了同样的问题,我被告知要初始化我的squareChecker变量,所以我就这样做了。由于一些我不知道的原因,我仍然会犯同样的错误。我花了一整天的时间独自解决这个问题,但没有结果。有人知道我的问题是什么吗?
我的普通模式类(在这里,我从square类调用方法并呈现事物):
public class NormalMode extends BasicGameState {
private Square[][] square = new Square[4][4];
private Square squareChecker;
Graphics g;
pu
在我的在线Java类中,我有这样的代码:
/* This is option 1 of my Java final project. This is a program which displays a frame with a button that, when you click it, increases the number below it. */
import java.awt.*; // imports everything I need for this project
import java.awt.event.MouseEvent;
import java.awt.eve
在下面的示例中,'this‘用于初始化sinstance。
public class MyApplication extends Application
{
public static MyApplication sinstance;
@Override
public void onCreate()
{
super.onCreate();
sinstance=this;
}
据我所知,“此”指的是对象的当前实例。如果我错了,请纠正我。现在考虑下面的程序
public static MyApplication