这是我的第一篇文章，所以对我很轻松。 我正在做一些单一的工作，我不是要求整个项目提供任何帮助或建议。 基本上，当我注释掉一个for循环时，整个事情确实有点工作：
for(int i=0;i<words.length;i++)
{
textArea.append(words[i] + "\n");
}
这是为了通过数组工作，但NetBeans一直告诉我将其更改为增强的for循环，但当我这样做时崩溃。整个程序旨在从JAplet接口获取输入，将其发送到单独的java文件中的stringAnalyser，记录单词的长度以及该长度的单词出现的频率，然后将其发回到界面并在中央控制台的屏幕上打印它们。
以下是我使用的两个文件，如果有帮助的话：
package Assignment2;
import java.awt.BorderLayout;
import java.awt.Color;
import java.awt.Container;
import java.awt.FlowLayout;
import java.awt.Font;
import java.awt.Graphics;
import java.awt.GridLayout;
import java.awt.Image;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;
import java.awt.event.WindowListener;
import javax.swing.*;
import javax.swing.border.BevelBorder;
import javax.swing.JPanel;
public class GUIAssign extends JApplet
{
private JPanel pnorth,psouth,pcentre,pwest,peast;
private JButton btnEnter,btnReset,btnSave,btnLoad;
private JTextField txtEnter;
private JLabel label1,label2,header;
private JTextArea textArea;
private Container c;
private paintPanel panelpaint;
private String inputString,shape;
private int x,y,size;
private stringAnalyser tim;
@Override
public void init()
{
this.setVisible(true);
this.setSize(800,600);
initComponents();
initPanels();
initButtons();
initText();
initLabels();
tim=new stringAnalyser();
}
public void initComponents()
{
x=0;
y=0;
size=0;
this.panelpaint=new paintPanel();
}
public void initPanels()
{
pnorth= new JPanel();
pnorth.setBackground(Color.CYAN);
this.psouth = new JPanel();
psouth.setBackground(Color.BLUE);
this.peast =new JPanel();
peast.setBackground(Color.CYAN);
this.pwest = new JPanel();
pwest.setBackground(Color.CYAN);
this.pcentre = new JPanel();
pcentre.setBackground(Color.yellow);
}
String words[];
public void initButtons()
{
this.btnEnter=new JButton("Enter");
btnEnter.addActionListener(new ActionListener() {
@Override
public void actionPerformed(ActionEvent ae) {
inputString=txtEnter.getText();
tim.setText(inputString);
words=tim.sendBack();
for(int i=0;i<words.length;i++)
{
textArea.append(words[i] + "\n");
}
tim.output();
}
});
this.btnReset=new JButton("Reset");
btnReset.addActionListener(new ActionListener(){
@Override
public void actionPerformed(ActionEvent ae) {
txtEnter.setText("");
}
});
this.btnSave=new JButton("Save");
this.btnLoad=new JButton("Load");
}
public void initText()
{
txtEnter=new JTextField();
textArea=new JTextArea();
}
public void initLabels()
{
this.label1=new JLabel("");
this.label2=new JLabel("");
}
//structure
@Override
public void start()
{
panelEast();
panelWest();
panelNorth();
panelSouth();
panelCentre();
c=this.getContentPane();
c.setBackground(Color.LIGHT_GRAY);
c.setLayout(new BorderLayout());
c.add(pnorth,BorderLayout.NORTH);
c.add(peast,BorderLayout.EAST);
c.add(psouth,BorderLayout.SOUTH);
c.add(pwest,BorderLayout.WEST);
c.add(pcentre,BorderLayout.CENTER);
}
public void panelNorth()
{
Font f=new Font("Jokerman",Font.BOLD,16);
pnorth.setLayout(new GridLayout(1,3));
pnorth.add(new JLabel(" "));
pnorth.add(new JLabel("Tim's String Lenght Tester"));
pnorth.add(new JLabel(" "));
}
public void panelWest()
{
pwest.add(new JLabel(" "));
//pwest.add(new JLabel(new ImageIcon("src/tim.jpg")));
}
public void panelEast()
{
peast.add(new JLabel(" "));
}
public void panelSouth()
{
psouth.setLayout(new FlowLayout());
JPanel psouth1=new JPanel();
JPanel psouth2=new JPanel();
psouth1.setLayout(new GridLayout(1,3));
psouth1.setBackground(Color.CYAN);
psouth1.setBorder(BorderFactory.createBevelBorder(BevelBorder.RAISED,Color.cyan, Color.black, Color.black, Color.cyan));
psouth1.add(this.txtEnter);
psouth1.add(this.btnEnter);
psouth1.add(this.btnReset);
psouth2.setLayout(new GridLayout(1,2));
psouth2.setBackground(Color.LIGHT_GRAY);
psouth2.setBorder(BorderFactory.createBevelBorder(BevelBorder.RAISED,Color.cyan, Color.black, Color.black, Color.cyan));
psouth2.add(this.btnSave);
psouth2.add(this.btnLoad);
psouth.add(psouth1);
psouth.add(psouth2);
}
public void panelCentre()
{
pcentre.setLayout(new GridLayout(1,2));
JPanel pcentre1=new JPanel();
pcentre.setBackground(Color.GREEN);
pcentre.setBorder(BorderFactory.createBevelBorder(BevelBorder.RAISED,Color.green,Color.green));
pcentre.add(textArea);
textArea.setBackground(Color.LIGHT_GRAY);
textArea.setForeground(Color.YELLOW);
pcentre.add(pcentre1);
}
@Override
public void setName(String n) {
this.inputString=n;
}
public String getNameString() {
return inputString;
}
@Override
public void stop(){}
@Override
public void destroy(){}
@Override
public void paint(Graphics g){
}
}//close project`
文件2，这是分析java文件：
package Assignment2;
public class stringAnalyser{
//static String inputArray[]= {"Tim","John","Craig", "Andrew", "Bob", "Tom", "Phillipa","Billie-Bob"};
private String inputString = "";
private String removedCharString;//will store the string with removed chars
private String array3="",array4="", array5="", array6="", array7="", array8="", array9="", array10="",array11="",
array12="",array13="",array14="",array15="";
private String[] sendString;
private int count=0;
//will add the words with the appropriate length to a string for printing
public void setText(String input)
{
this.inputString=input;
}
public String showme()
{
return "Think is not difficult believe is the word and look at me I am the great evidence!!!";
}
public void output()
{
int three=0, four=0, five=0, six=0, seven=0, eight=0, nine=0, ten=0,eleven=0,twelve=0,thirt=0,fort=0,fift=0;
// these ints will count how many times the words relevent length have accoured in a string
String w[];
removedCharString = inputString.replaceAll("[^a-zA-Z\\s]", "");//remove chars
w=removedCharString.split(" ");
this.sendString=new String[w.length];
for (String retval: removedCharString.split(" "))//split at any spaces
{
if (retval.length()==3){
three++;
array3 = array3 + retval + ", ";
}//if 3
if (retval.length()==4){
four++;
array4 = array4 + retval + ", ";
}//if 4
if (retval.length()==5){
five++;
array5 = array5 + retval + ", ";
}//if 5
if (retval.length()==6){
six++;
array6 = array6 + retval + ", ";
}//if 6
if (retval.length()==7){
seven++;
array7 = array7 + retval + ", ";
}//if 7
if (retval.length()==8){
eight++;
array8 = array8 + retval + ", ";
}//if 8
if (retval.length()==9){
nine++;
array9 = array9 + retval + ", ";
}//if 9
if (retval.length()==10){
ten++;
array10 = array10 + retval + ", ";
}//if 10
if (retval.length()==11){
eleven++;
array11 = array11 + retval + ", ";
}//if 10
if (retval.length()==12){
twelve++;
array12 = array12 + retval + ", ";
}//if 10
if (retval.length()==13){
thirt++;
array13 = array13 + retval + ", ";
}//if 10
if (retval.length()==14){
fort++;
array14 = array14 + retval + ", ";
}//if 10
if (retval.length()==15){
fift++;
array15 = array15 + retval + ", ";
}//if 10
}//for string retval
// print the results
System.out.println(inputString);
if (three!=0){
count++;
sendString[count]="There are: "+three+" three letter word/s; "+array3;
System.out.println("There are: "+three+" three letter word/s; "+array3);}
if (four!=0){
count++;
sendString[count]="There are: "+four+" four letter word/s; "+array4;
System.out.println("There are: "+four+" four letter word/s; "+array4);}
if (five!=0){
System.out.println("There are: "+five+" five letter word/s; "+array5);}
if (six !=0){
System.out.println("There are: "+six+" six letter word/s; "+array6);}
if (seven !=0){
System.out.println("There are: "+seven+" seven letter word/s; "+array7);}
if (eight!=0){
System.out.println("There are: "+eight+" eigth letter word/s; "+array8);}
if (nine!=0){
System.out.println("There are: "+nine+" nine letter word/s; "+array9);}
if (ten!=0){
System.out.println("There are: "+ten+" ten letter word/s;"+array10);}
if (eleven!=0){
System.out.println("There are: "+eleven+" eleven letter word/s;"+array11);}
if (twelve!=0){
System.out.println("There are: "+twelve+" twelve letter word/s;"+array12);}
if (thirt!=0){
System.out.println("There are: "+thirt+" thirteen letter word/s;"+array13);}
if (fort!=0){
System.out.println("There are: "+fort+" forteen letter word/s;"+array14);}
if (fift!=0){
System.out.println("There are: "+fift+" fifteen letter word/s;"+array15);}
}//output
public String[] sendBack()
{
return this.sendString;
}
public static void main(String []args)
{
stringAnalyser a=new stringAnalyser();
a.output();
}//close main
}//class`
提前感谢您提供任何和所有意见。
答案 0 :(得分：0)
似乎在btnEnter.addActionListener中你只调用设置输入的tim.setText(inputString);。但是你永远不会在分析器上调用output()或任何其他必需的方法来处理输入。因此，tim.sendBack()会返回null。 stringAnalyser.sendString仅在output()内初始化。在那之前它仍然是null。因此words.length会触发NullPointerException，因为words数组是null。
发布的代码的缩进和命名有时难以遵循。请参阅Java Code Conventions，Naming Conventions部分。大多数工具都可以自动缩进代码，即Eclipse中的 ctrl + shift + f 。