为什么 Eclipse 说“存在错误”但在控制台中什么也没显示？

Question

I am using Eclipse to build a program and when I go to run it, it says that "errors exist", I run it anyway, there are no errors showing up in the console and the application runs a blank screen. Why is this?

Additional Info: I recently have been trying to change my previous layout, from a very crude form, to utilizing GridBagLayout, however i am not very familiar with using layouts. I strongly suspect the problem lies in, or revolves around, my layout since the program properly functioned before I tried making changes.

Here are my two main classes that involve the layout, sorry for it being messy, I commented out a lot of lines that worked for the previous layout in case I have to revert back to it:

import java.awt.*;
import java.sql.SQLException;
import java.util.LinkedList;

import javax.swing.ImageIcon;
import javax.swing.JButton;
import javax.swing.JFrame;
import javax.swing.JLabel;
import javax.swing.JLayeredPane;
import javax.swing.JPanel;
import javax.swing.Timer;
import javax.swing.UIManager;
import javax.swing.border.Border;
import javax.swing.plaf.ColorUIResource;

import java.sql.*;

public class MainDisplay extends JFrame {

static Toolkit tk = Toolkit.getDefaultToolkit();
static int Width = (int)tk.getScreenSize().getWidth();
static int Height = (int)tk.getScreenSize().getHeight();

//public static JFrame frame = new JFrame();
public static JPanel pane = new JPanel();


private static String targetIpHolder;
private static String attackerIpHolder;
private static int threatLevelHolder; 
private static String numAttacksHolder;

public static void main (String[] args) {
new MainDisplay();

}

public MainDisplay() {


setPreferredSize(new Dimension(Width, Height));
setLocation(0,0);
setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
setUndecorated(true);



//pane.setLayout(gridBag);
setLayout(new BorderLayout());
//add(pane, BorderLayout.CENTER);
pane.setBounds(0,0, Width, Height);

pack();
setVisible(true);

ThreatPanel Run = new ThreatPanel();
Database Data = new Database();

//Create Connection to Database and run query

Data.createConnection();
Data.getData();
    try {
        while(Data.rslt.next()){
            Data.process();
            targetIpHolder = Data.getTarget();
            attackerIpHolder = Data.getAttacker();
            threatLevelHolder = Data.getThreat_level();
            numAttacksHolder = Data.getNum_attack();
            //System.out.println(targetIpHolder);
            //System.out.println(attackerIpHolder);
            Run.ShowThreats();
            try {
                Thread.sleep(1000*1); 
            } catch (InterruptedException e) {

                e.printStackTrace();
            }

        }
    } catch (SQLException e) {

        e.printStackTrace();
    }



}

public static String getTargetIpHolder(){
return targetIpHolder;
}
public static String getAttackerIpHolder(){
return attackerIpHolder;
}
public static int getThreatLevelHolder(){
return threatLevelHolder;
}
public static String getNumAttacks(){
return numAttacksHolder;
}

}

---

import java.awt.Color;
import java.awt.Font;
import java.awt.GridBagConstraints;
import java.awt.GridBagLayout;
import java.awt.Image;
import java.awt.image.RenderedImage;
import java.io.BufferedInputStream;
import java.io.BufferedReader;
import java.io.ByteArrayOutputStream;
import java.io.File;
import java.io.IOException;
import java.io.InputStream;
import java.io.InputStreamReader;
import java.net.MalformedURLException;
import java.net.URL;


import javax.imageio.ImageIO;
import javax.swing.Icon;
import javax.swing.ImageIcon;
import javax.swing.JLabel;
import javax.swing.JPanel;
import javax.swing.SwingConstants;



public class ThreatPanel {

JPanel BackPanel = new JPanel();
//JPanel HeadingBreak = new JPanel();
JPanel DarkPanel = new JPanel();
//JPanel HeadingBreak = new JPanel();
//JPanel HorizontalSplit1 = new JPanel();
//JPanel HorizontalSplit2 = new JPanel();
//JPanel VerticalSplit = new JPanel();

public GridBagLayout gridBag = new GridBagLayout();
public GridBagConstraints gbc = new GridBagConstraints();


final int TEST = 0;
final int TEST2 = 100;
final int TEST3 = 200;

private String city;
private String region;
private String latitude;
private String longitude;
private Image img;
private ImageIcon icon;

Color severeColor = new Color(225,102,00);

URL geoLocRetriever;


//Target area declarations. 
String Client = "CLIENT"; //filler
JLabel Target = new JLabel("TARGET");
JLabel ClientLabel = new JLabel(Client); //filler
JLabel TargetServerData;
JLabel ServerID = new JLabel("SERVER ID");

//Attacker area declarations.
JLabel Attacker = new JLabel("ATTACKER");
JLabel AttackerData;
JLabel GeoLocData;
JLabel GeoLocImg;
JLabel GeoLocLabel = new JLabel("GEO LOCATION");

//Threat Level area declarations.
JLabel ThreatLevel = new JLabel("THREAT");
JLabel ThreatLevelData;

//Number of Attacks declarations
JLabel NumberOfAttacks = new JLabel("ATTACKS");
JLabel NumberOfAttacksData;


public ThreatPanel()
{
DarkPanel.setLayout(gridBag);

TargetServerData = new JLabel();
AttackerData = new JLabel();
ThreatLevelData = new JLabel();
NumberOfAttacksData = new JLabel();
GeoLocData = new JLabel();
GeoLocImg = new JLabel();


BackPanel.setLayout(null);
BackPanel.setBackground(Color.WHITE);
BackPanel.setBounds(0,0, MainDisplay.Width, MainDisplay.Height);
BackPanel.setOpaque(true);
/*
HeadingBreak.setBackground(Color.WHITE);
HeadingBreak.setBounds(0, 80, MainDisplay.Width, 3);
HeadingBreak.setOpaque(true);
*/
/*
HorizontalSplit1.setBackground(Color.WHITE);
HorizontalSplit1.setBounds(0, MainDisplay.Height/2, MainDisplay.Width, 3);
HorizontalSplit1.setOpaque(true);
*/
/*
HorizontalSplit2.setBackground(Color.WHITE);
HorizontalSplit2.setBounds(0, MainDisplay.Height/2+80, MainDisplay.Width, 3);
HorizontalSplit2.setOpaque(true);
*/
/*
VerticalSplit.setBackground(Color.WHITE);
VerticalSplit.setBounds((int)(MainDisplay.Width/1.5), 0, 3, MainDisplay.Height);
VerticalSplit.setOpaque(true);
*/
//Target area settings. 

Target.setFont(new Font("Arial", Font.BOLD, 85));
Target.setForeground(Color.GREEN);
Target.setBounds(0, 0, ((int)(MainDisplay.Width/1.5)-3), 75);
Target.setHorizontalAlignment(SwingConstants.CENTER);
gbc.gridx = 0;
gbc.gridy = 0;
gbc.fill = GridBagConstraints.HORIZONTAL;
DarkPanel.add(Target, gbc);

ClientLabel.setForeground(Color.WHITE);
ClientLabel.setFont(new Font("Arial", Font.BOLD, 100));
ClientLabel.setBounds(0, 115, ((int)(MainDisplay.Width/1.5)-3), 95);
ClientLabel.setHorizontalAlignment(SwingConstants.CENTER);
gbc.gridx = 0;
gbc.gridy = 1;
gbc.fill = GridBagConstraints.HORIZONTAL;
DarkPanel.add(ClientLabel, gbc);


TargetServerData.setForeground(Color.WHITE);
TargetServerData.setFont(new Font("Arial", Font.BOLD, 120));
TargetServerData.setBounds(0, 230, ((int)(MainDisplay.Width/1.5)-3), 95);
TargetServerData.setHorizontalAlignment(SwingConstants.CENTER);
gbc.gridx = 0;
gbc.gridy = 2;
gbc.fill = GridBagConstraints.HORIZONTAL;
DarkPanel.add(TargetServerData, gbc);

ServerID.setForeground(Color.WHITE);
ServerID.setFont(new Font("Arial", Font.BOLD, 120));
ServerID.setBounds(0, 230, ((int)(MainDisplay.Width/1.5)-3), 95);
ServerID.setHorizontalAlignment(SwingConstants.CENTER);
gbc.gridx = 0;
gbc.gridy = 3;
gbc.fill = GridBagConstraints.HORIZONTAL;
DarkPanel.add(ServerID, gbc);

Attacker.setFont(new Font("Arial", Font.BOLD, 85));
Attacker.setForeground(Color.RED);
Attacker.setBounds(0, (MainDisplay.Height/2)+3, ((int)(MainDisplay.Width/1.5)-3), 75);
Attacker.setHorizontalAlignment(SwingConstants.CENTER);
gbc.gridx = 0;
gbc.gridy = 4;
gbc.fill = GridBagConstraints.HORIZONTAL;
DarkPanel.add(Attacker, gbc);

AttackerData.setForeground(Color.RED);
AttackerData.setFont(new Font("Arial", Font.BOLD, 70));
AttackerData.setBounds(0, ((int)(MainDisplay.Height/1.5)-3), ((int)(MainDisplay.Width/1.5)-3), 75);
AttackerData.setHorizontalAlignment(SwingConstants.CENTER);
gbc.gridx = 0;
gbc.gridy = 5;
gbc.fill = GridBagConstraints.HORIZONTAL;
DarkPanel.add(AttackerData, gbc);

GeoLocData.setFont(new Font("Arial", Font.BOLD, 70));
GeoLocData.setForeground(Color.RED);
GeoLocData.setBounds(0, (int)(MainDisplay.Height/1.2), ((int)(MainDisplay.Width/1.5)-3), 75);
GeoLocData.setHorizontalAlignment(SwingConstants.CENTER);
gbc.gridx = 0;
gbc.gridy = 6;
gbc.fill = GridBagConstraints.HORIZONTAL;
DarkPanel.add(GeoLocData, gbc);

ThreatLevel.setFont(new Font("Arial", Font.BOLD, 85));
ThreatLevel.setForeground(Color.GREEN);
ThreatLevel.setBounds(725, 0, ((int)(MainDisplay.Width/1.5)-3), 75);
ThreatLevel.setHorizontalAlignment(SwingConstants.CENTER);
gbc.gridx = 1;
gbc.gridy = 0;
gbc.fill = GridBagConstraints.HORIZONTAL;
DarkPanel.add(ThreatLevel, gbc);

ThreatLevelData.setFont(new Font("Arial", Font.BOLD, 100));
ThreatLevelData.setBounds(725, 105, ((int)(MainDisplay.Width/1.5)-3), 95);
ThreatLevelData.setHorizontalAlignment(SwingConstants.CENTER);
gbc.gridx = 1;
gbc.gridy = 1;
gbc.fill = GridBagConstraints.HORIZONTAL;
DarkPanel.add(ThreatLevelData, gbc);


NumberOfAttacks.setFont(new Font("Arial", Font.BOLD, 85));
NumberOfAttacks.setForeground(Color.RED);
NumberOfAttacks.setBounds(725, (MainDisplay.Height/2)+3, ((int)(MainDisplay.Width/1.5)-3), 75);
NumberOfAttacks.setHorizontalAlignment(SwingConstants.CENTER);
gbc.gridx = 1;
gbc.gridy = 2;
gbc.fill = GridBagConstraints.HORIZONTAL;
DarkPanel.add(NumberOfAttacks, gbc);

NumberOfAttacksData.setFont(new Font("Arial", Font.BOLD, 85));
NumberOfAttacksData.setForeground(Color.RED);
NumberOfAttacksData.setBounds(725, (int) ((MainDisplay.Height/1.5)), ((int)(MainDisplay.Width/1.5)-3), 75);
NumberOfAttacksData.setHorizontalAlignment(SwingConstants.CENTER);
gbc.gridx = 1;
gbc.gridy = 3;
gbc.fill = GridBagConstraints.HORIZONTAL;
DarkPanel.add(NumberOfAttacksData, gbc);

GeoLocLabel.setFont(new Font("Arial", Font.BOLD, 85));
GeoLocLabel.setForeground(Color.RED);
GeoLocLabel.setBounds(0, (MainDisplay.Height/2)+3, ((int)(MainDisplay.Width/1.5)-3), 75);
GeoLocLabel.setHorizontalAlignment(SwingConstants.CENTER);
gbc.gridx = 1;
gbc.gridy = 4;
gbc.fill = GridBagConstraints.HORIZONTAL;
DarkPanel.add(GeoLocLabel, gbc);

GeoLocImg.setBounds(1050, 590, 300, 300);
GeoLocImg.setHorizontalAlignment(SwingConstants.CENTER);
gbc.gridx = 1;
gbc.gridy = 5;
gbc.gridheight = 2;
gbc.fill = GridBagConstraints.HORIZONTAL;
DarkPanel.add(GeoLocData, gbc);

//Remaining settings.
/*
//DarkPanel.setLayout(null);
//DarkPanel.setBackground(Color.BLACK);
//DarkPanel.setBounds(3, 3, ((MainDisplay.Width)-6), ((MainDisplay.Height)-6));
//DarkPanel.setOpaque(true);
////DarkPanel.add(Target);
//DarkPanel.add(HeadingBreak);
//DarkPanel.add(VerticalSplit);
//DarkPanel.add(HorizontalSplit1);
//DarkPanel.add(HorizontalSplit2);
DarkPanel.add(ClientLabel);
DarkPanel.add(TargetServerData);
DarkPanel.add(ThreatLevel);
DarkPanel.add(ThreatLevelData);
DarkPanel.add(Attacker);
DarkPanel.add(AttackerData);
DarkPanel.add(NumberOfAttacks);
DarkPanel.add(NumberOfAttacksData);
DarkPanel.add(GeoLocData);
DarkPanel.add(GeoLocImg);
*/

BackPanel.add(DarkPanel);

MainDisplay.pane.add(BackPanel, new Integer(0), 0);

}

public void getGeoLoc()
{
String locHolder;
try {
    geoLocRetriever = new URL("http://ip-api.com/line/*******"); //+ MainDisplay.getAttackerIpHolder()
} catch (MalformedURLException e) {
    e.printStackTrace();
}

InputStream stream = null;
try {
    stream = geoLocRetriever.openStream();
} catch (IOException e1) {
    e1.printStackTrace();
}
ByteArrayOutputStream buffer = new ByteArrayOutputStream();
if (stream != null) try {
    final BufferedInputStream input = new BufferedInputStream(stream);
    final byte[] reader = new byte[16384];
    int r = 0;
    while ((r = input.read(reader, 0, 16384)) != -1)
        buffer.write(reader, 0, r);
    buffer.flush();
} catch(IOException e) {
    e.printStackTrace();
} finally {
    if(stream != null) try {
        stream.close();
    } catch(IOException e) {
        e.printStackTrace();
    }
}


locHolder = new String(buffer.toByteArray());
String[] lines = locHolder.split("\n");
//System.out.print(lines[5]);

city = lines[5];
region = lines[4];
latitude = lines[7];
longitude = lines[8];

String temp;
temp="https://maps.googleapis.com/maps/api/staticmap?center=" +latitude +"," +longitude +"&zoom=7&size=300x300&markers=color:red|label:A|" +latitude +"," +longitude +"&sensor=false";
URL mapurl = null;
try {
    mapurl = new URL(temp);
} catch (MalformedURLException e) {
    e.printStackTrace();
}
try {
    img = ImageIO.read(mapurl);
} catch (IOException e) {
    e.printStackTrace();
}
icon = new ImageIcon(img);  
}

public void ShowThreats(){

    String targetEnd = MainDisplay.getTargetIpHolder();     
    TargetServerData.setText(targetEnd);

    String attackerEnd = MainDisplay.getAttackerIpHolder();
    AttackerData.setText(attackerEnd);

    getGeoLoc();
    String geoLocEnd = city + "," + region;
    GeoLocData.setText(geoLocEnd);
    GeoLocImg.setIcon(icon);


    int threatLevelEnd = MainDisplay.getThreatLevelHolder();
    //System.out.println(threatLevelEnd);
    if ((threatLevelEnd > TEST ) && (threatLevelEnd < TEST2)){
        ThreatLevelData.setText("WARNING");
        ThreatLevelData.setForeground(Color.YELLOW);
    }
    else if ((threatLevelEnd > TEST2 ) && (threatLevelEnd < TEST3)){
        ThreatLevelData.setText("SEVERE");
        ThreatLevelData.setForeground(severeColor);
    }
    else if (threatLevelEnd > TEST3){
        ThreatLevelData.setText("CRITICAL");
        ThreatLevelData.setForeground(Color.RED);
    }
    else{
        ThreatLevelData.setText("ERROR");
        ThreatLevelData.setForeground(Color.PINK);
    }

    String numAttacksEnd = MainDisplay.getNumAttacks();
    NumberOfAttacksData.setText(numAttacksEnd);
    //System.out.println(numAttacksEnd);

}

}

Answer 1

Go to Window --> Show View --> general --> Problems and you will see the list of errors. In my case - I had a wrong source folder in Build Path. Configuring Build Path solved the "Error exists in your project" issue. In the 'problems' view - rt click on the error and quick fix- this solved the issue.

Answer 2

It may be a JRE error. Right click the project root and select preferences. Come to installed JREs and look for an error. Also, rebuild the project and check Window > Show View > Error Log , as suggested in a comment by @Ted Hopp.

Answer 3

好的，就我而言， Problems视图中没有任何内容，帮助我的是更新 maven 依赖项（右键单击项目 > Maven > 更新项目），我选择所有相关项目，然后警告消失。

Answer 4

Go to Window → Show View → general → Problems and you will see the list of errors. In my case, some of the JAR files were missing on the build path. Configuring Build Path solved the "Error exists in your project" issue. In the 'problems' view, right click on the error and quick fix.