在我已初始化的数组上收到 java.lang.NullPointerException，但我无法完全弄清楚做错了什么。错误发生在第 371 行。
下面是父类的代码，后面是初始化 letterArray ArrayList 的类:
package wordsearch;
import java.awt.BorderLayout;
import java.awt.Color;
import java.awt.Dimension;
import java.awt.GridLayout;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;
import java.awt.geom.Line2D;
import java.io.IOException;
import java.io.PrintStream;
import java.util.ArrayList;
import java.util.Arrays;
import java.util.List;
import javax.swing.DefaultListModel;
import javax.swing.JButton;
import javax.swing.JFrame;
import javax.swing.JLabel;
import javax.swing.JOptionPane;
import javax.swing.JPanel;
import javax.swing.JScrollPane;
import javax.swing.JTextArea;
import javax.swing.SwingConstants;
/**
* Main class of Puzzle Program
* @author mungaialex
*
*/
public class WordSearchPuzzle extends JFrame {
private static final long serialVersionUID = 1L;
/** No. Of Columns in Wordlist*/
private static final int WORDLISTCOLS = 1;
static JButton[][] grid; //names the grid of buttons
GridLayout myGridLayout = new GridLayout(1,2,3,3);
/**Array to hold wordList*/
ArrayList<String> wordList;
JButton btnCheck, btnClear;
/** Panel to hold Components to the left*/
JPanel leftSidePanel;
/** Panel to hold components to the right*/
JPanel rightSidePanel;
/**Panel to hold word List*/
JPanel wordListPanel;
/**Panel to hold grid buttons*/
JPanel gridPanel;
/**Panel to hold clear button and check button*/
JPanel buttonsPanel;
/**Panel to hold output textarea*/
JPanel bottomPanel;
private JLabel[] wordListComponents;
@SuppressWarnings("rawtypes")
List puzzleLines;
//Grid Size
private final int ROWS = 20;
private final int COLS = 20;
/** Output Area of system*/
private JTextArea txtOutput;
/**Scrollpane for Output area*/
private JScrollPane scptxtOutput;
private Object[] theWords;
public String wordFromChars = new String();
/** the matrix of the letters */
private char[][] letterArray = null;
/**
* Constructor for WordSearchPuzzle
* @param wordListFile File Containing words to Search for
* @param wordSearhPuzzleFile File Containing the puzzle
*/
public WordSearchPuzzle(String wordSearchFile,String wordsListFile) throws IOException {
FileIO io = new FileIO(wordSearchFile,wordsListFile,grid);
wordList = io.loadWordList();
theWords = wordList.toArray();
addComponentsToPane();
buildWordListPanel();
buildBottomPanel();
io.loadPuzleFromFile();
//Override System.out
PrintStream stream = new PrintStream(System.out) {
@Override
public void print(String s) {
txtOutput.append(s + "\n");
txtOutput.setCaretPosition(txtOutput.getText().length());
}
};
System.setOut(stream);
System.out.print("MESSAGES");
}
/**
* Constructor two
*/
public WordSearchPuzzle() {
}
/**
* Gets the whole word of buttons clicked
* @return
* Returns whole Word
*/
public String getSelectedWord() {
return wordFromChars;
}
/**
* Adds word lists to Panel on the left
*/
private void buildWordListPanel() {
leftSidePanel.setBackground(Color.WHITE);
// Build the word list
wordListComponents = new JLabel[wordList.size()];
wordListPanel = new JPanel(new GridLayout(25, 1));
wordListPanel.setBackground(Color.white);
//Loop through list of words
for (int i = 0; i < this.wordList.size(); i++) {
String word = this.wordList.get(i).toUpperCase();
wordListComponents[i] = new JLabel(word);
wordListComponents[i].setForeground(Color.BLUE);
wordListComponents[i].setHorizontalAlignment(SwingConstants.LEFT);
wordListPanel.add(wordListComponents[i]);
}
leftSidePanel.add(wordListPanel,BorderLayout.WEST);
}
/**
* Adds an output area to the bottom of
*/
private void buildBottomPanel() {
bottomPanel = new JPanel();
bottomPanel.setLayout(new BorderLayout());
txtOutput = new JTextArea();
txtOutput.setEditable(false);
txtOutput.setRows(5);
scptxtOutput = new JScrollPane(txtOutput);
bottomPanel.add(txtOutput,BorderLayout.CENTER);
bottomPanel.add(scptxtOutput,BorderLayout.SOUTH);
rightSidePanel.add(bottomPanel,BorderLayout.CENTER);
}
/**
* Initialize Components
*/
public void addComponentsToPane() {
// buttonsPanel = new JPanel(new BorderLayout(3,5)); //Panel to hold Buttons
buttonsPanel = new JPanel(new GridLayout(3,1));
leftSidePanel = new JPanel(new BorderLayout());
rightSidePanel = new JPanel(new BorderLayout());
btnCheck = new JButton("Check Word");
btnCheck.setActionCommand("Check");
btnCheck.addActionListener(new ButtonClickListener());
btnClear = new JButton("Clear Selection");
btnClear.setActionCommand("Clear");
btnClear.addActionListener(new ButtonClickListener());
buttonsPanel.add(btnClear);//,BorderLayout.PAGE_START);
buttonsPanel.add(btnCheck);//,BorderLayout.PAGE_END);
leftSidePanel.add(buttonsPanel,BorderLayout.SOUTH);
this.getContentPane().add(leftSidePanel,BorderLayout.LINE_START);
gridPanel = new JPanel();
gridPanel.setLayout(myGridLayout);
myGridLayout.setRows(20);
myGridLayout.setColumns(20);
grid = new JButton[ROWS][COLS]; //allocate the size of grid
//theBoard = new char[ROWS][COLS];
for(int Row = 0; Row < grid.length; Row++){
for(int Column = 0; Column < grid[Row].length; Column++){
grid[Row][Column] = new JButton();//Row + 1 +", " + (Column + 1));
grid[Row][Column].setActionCommand(Row + "," + Column);
grid[Row][Column].setActionCommand("gridButton");
grid[Row][Column].addActionListener(new ButtonClickListener());
gridPanel.add(grid[Row][Column]);
}
}
rightSidePanel.add(gridPanel,BorderLayout.NORTH);
this.getContentPane().add(rightSidePanel, BorderLayout.CENTER);
}
public static void main(String[] args) {
try {
if (args.length !=2) { //Make sure we have both the puzzle file and word list file
JOptionPane.showMessageDialog(null, "One or All Files are Missing");
} else { //Files Found
WordSearchPuzzle puzzle = new WordSearchPuzzle(args[0],args[1]);
puzzle.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
puzzle.setSize(new Dimension(1215,740));
//Display the window.
puzzle.setLocationRelativeTo(null); // Center frame on screen
puzzle.setResizable(false); //Set the form as not resizable
puzzle.setVisible(true);
}
} catch (Exception e) {
System.out.println(e.getMessage());
e.printStackTrace();
}
}
public int solvePuzzle( ){
int matches = 0;
for( int r = 0; r < ROWS; r++ )
for( int c = 0; c < COLS; c++ )
for( int rd = -1; rd <= 1; rd++ )
for( int cd = -1; cd <= 1; cd++ )
if( rd != 0 || cd != 0 )
matches += solveDirection( r, c, rd, cd );
return matches;
}
private int solveDirection( int baseRow, int baseCol, int rowDelta, int colDelta ){
String charSequence = "";
int numMatches = 0;
int searchResult;
FileIO io = new FileIO();
charSequence += io.theBoard[ baseRow ][ baseCol ];
for( int i = baseRow + rowDelta, j = baseCol + colDelta;
i >= 0 && j >= 0 && i < ROWS && j < COLS;
i += rowDelta, j += colDelta )
{
charSequence += io.theBoard[ i ][ j ];
searchResult = prefixSearch( theWords, charSequence );
if( searchResult == theWords.length )
break;
if( !((String)theWords[ searchResult ]).startsWith( charSequence ) )
break;
if( theWords[ searchResult ].equals( charSequence ) )
{
numMatches++;
System.out.println( "Found " + charSequence + " at " +
baseRow + " " + baseCol + " to " +
i + " " + j );
}
}
return numMatches;
}
private static int prefixSearch( Object [ ] a, String x ) {
int idx = Arrays.binarySearch( a, x );
if( idx < 0 )
return -idx - 1;
else
return idx;
}
class ButtonClickListener implements ActionListener {
@Override
public void actionPerformed(ActionEvent e) {
String command = ((JButton)e.getSource()).getActionCommand();
if (command == "Clear") {
//Enable the buttons that have been disabled and not form a whole word
//JOptionPane.showMessageDialog(null, "Cooming Soon");
for (String word : wordList) {
System.out.print(word);
}
} else if (command == "Check") {
String selectedWord = getSelectedWord();
if (!selectedWord.equals("")){
System.out.print("Selected word is " + getSelectedWord());
//First check if selected word exits in wordList
if (ifExists(selectedWord)) {
if(searchWord(selectedWord)){
JOptionPane.showMessageDialog(null, "Success");
wordFromChars = ""; //Reset the selected Word
}
} else {
JOptionPane.showMessageDialog(null, "[" + selectedWord + "] " +
"Does Not Belong to Word list");
wordFromChars = ""; //Reset the selected Word
}
} else {
JOptionPane.showMessageDialog(null, "No Buttons on Grid have been clicked");
}
} else if (command == "gridButton") {
getSelectedCharacter(e);
((JButton)e.getSource()).setEnabled(false);
}
}
/**
* Gets the character of each button and concatenates each character to form a whole word
* @param e The button that received the Click Event
* @return Whole word
*/
private String getSelectedCharacter (ActionEvent e) {
String character;
character = ((JButton) e.getSource()).getText();
wordFromChars = wordFromChars + character;
return wordFromChars;
}
}
/**
* Checks if selected word is among in wordlist
* @param selectedWord
* @return The word to search for
*/
private boolean ifExists(String selectedWord) {
if (wordList.contains(selectedWord)) {
return true;
}
return false;
}
public boolean searchWord(String word) {
if (!wordList.contains(word)) {
return false;
}
//int index = wordList.indexOf(word);
Line2D.Double line = new Line2D.Double();
//System.out.print("LetterArray is " + letterArray.length);
for (int x = 0; x < letterArray.length; x++) {
for (int y = 0; y < letterArray[x].length; y++) {
// save start point
line.x1 = y; // (y + 1) * SCALE_INDEX_TO_XY;
line.y1 = x; // (x + 1) * SCALE_INDEX_TO_XY;
int pos = 0; // current letter position
if (letterArray[x][y] == word.charAt(pos)) {
// first letter correct -> check next
pos++;
if (pos >= word.length()) {
// word is only one letter long
// double abit = SCALE_INDEX_TO_XY / 3;
line.x2 = y; // (y + 1) * SCALE_INDEX_TO_XY + abit;
line.y2 = x; // (x + 1) * SCALE_INDEX_TO_XY + abit;
return true;
}
// prove surrounding letters:
int[] dirX = { 1, 1, 0, -1, -1, -1, 0, 1 };
int[] dirY = { 0, -1, -1, -1, 0, 1, 1, 1 };
for (int d = 0; d < dirX.length; d++) {
int dx = dirX[d];
int dy = dirY[d];
int cx = x + dx;
int cy = y + dy;
pos = 1; // may be greater if already search in another
// direction from this point
if (insideArray(cx, cy)) {
if (letterArray[cx][cy] == word.charAt(pos)) {
// 2 letters correct
// -> we've got the direction
pos++;
cx += dx;
cy += dy;
while (pos < word.length() && insideArray(cx, cy)
&& letterArray[cx][cy] == word.charAt(pos)) {
pos++;
cx += dx;
cy += dy;
}
if (pos == word.length()) {
// correct end if found
cx -= dx;
cy -= dy;
pos--;
}
if (insideArray(cx, cy) && letterArray[cx][cy] == word.charAt(pos)) {
// we've got the end point
line.x2 = cy; // (cy + 1) *
// SCALE_INDEX_TO_XY;
line.y2 = cx; // (cx + 1) *
// SCALE_INDEX_TO_XY;
/*
* System.out.println(letterArray[x][y] +
* " == " + word.charAt(0) + " (" + line.x1
* + "," + line.y1 + ") ->" + " (" + line.x2
* + "," + line.y2 + "); " + " [" + (line.x1
* / SCALE_INDEX_TO_XY) + "," + (line.y1 /
* SCALE_INDEX_TO_XY) + "] ->" + " [" +
* (line.x2 / SCALE_INDEX_TO_XY) + "." +
* (line.y2 / SCALE_INDEX_TO_XY) + "]; ");
*/
//result[index] = line;
// found
return true;
}
// else: try next occurence
}
}
}
}
}
}
return false;
}
private boolean insideArray(int x, int y) {
boolean insideX = (x >= 0 && x < letterArray.length);
boolean insideY = (y >= 0 && y < letterArray[0].length);
return (insideX && insideY);
}
public void init(char[][] letterArray) {
try {
for (int i = 0; i < letterArray.length; i++) {
for (int j = 0; j < letterArray[i].length; j++) {
char ch = letterArray[i][j];
if (ch >= 'a' && ch <= 'z') {
letterArray[i][j] = Character.toUpperCase(ch);
}
}
}
} catch (Exception e){
System.out.println(e.toString());
}
//System.out.println("It is " + letterArray.length);
this.letterArray = letterArray;
}
}
这是初始化 letterArray 数组的类:
package wordsearch;
import java.awt.Color;
import java.io.BufferedReader;
import java.io.FileReader;
import java.io.IOException;
import java.util.ArrayList;
import java.util.Iterator;
import java.util.List;
import java.util.StringTokenizer;
import javax.swing.JButton;
import javax.swing.JOptionPane;
import javax.swing.SwingConstants;
/**
* Reads wordlist file and puzzle file
* @author mungaialex
*
*/
public class FileIO {
String _puzzleFile, _wordListFile;
/**ArrayList to hold words*/
ArrayList<String> wordList;
/** No. Of Columns in Wordlist*/
private static final int WORDLISTCOLS = 1;
List puzzleLines;
JButton[][] _grid;
char theBoard[][];
private final int _rows = 20;
private final int _columns = 20;
WordSearchPuzzle pz = new WordSearchPuzzle();
/**
* Default Constructor
* @param puzzleFile
* @param wordListFile
*/
public FileIO(String puzzleFile, String wordListFile,JButton grid[][]){
_puzzleFile = new String(puzzleFile);
_wordListFile = new String(wordListFile);
_grid = pz.grid;
}
public FileIO() {
}
/**
* Reads word in the wordlist file and adds them to an array
* @param wordListFilename
* File Containing Words to Search For
* @throws IOException
*/
protected ArrayList<String> loadWordList()throws IOException {
int row = 0;
wordList = new ArrayList<String>();
BufferedReader reader = new BufferedReader(new FileReader(_wordListFile));
String line = reader.readLine();
while (line != null) {
StringTokenizer tokenizer = new StringTokenizer(line, " ");
if (tokenizer.countTokens() != WORDLISTCOLS) {
JOptionPane.showMessageDialog(null, "Error: only one word per line allowed in the word list",
"WordSearch Puzzle: Invalid Format", row);//, JOptionPane.OK_CANCEL_OPTION);
//"Error: only one word per line allowed in the word list");
}
String tok = tokenizer.nextToken();
wordList.add(tok.toUpperCase());
line = reader.readLine();
row++;
}
reader.close();
return wordList;
}
/**
* Reads the puzzle file line by by line
* @param wordSearchFilename
* The file containing the puzzle
* @throws IOException
*/
protected void loadPuzleFromFile() throws IOException {
int row = 0;
BufferedReader reader = new BufferedReader(new FileReader(_puzzleFile));
StringBuffer sb = new StringBuffer();
String line = reader.readLine();
puzzleLines = new ArrayList<String>();
while (line != null) {
StringTokenizer tokenizer = new StringTokenizer(line, " ");
int col = 0;
sb.append(line);
sb.append('\n');
while (tokenizer.hasMoreTokens()) {
String tok = tokenizer.nextToken();
WordSearchPuzzle.grid[row][col].setText(tok);
pz.grid[row][col].setForeground(Color.BLACK);
pz.grid[row][col].setHorizontalAlignment(SwingConstants.CENTER);
puzzleLines.add(tok);
col++;
}
line = reader.readLine();
row++;
theBoard = new char[_rows][_columns];
Iterator itr = puzzleLines.iterator();
for( int r = 0; r < _rows; r++ )
{
String theLine = (String) itr.next( );
theBoard[ r ] = theLine.toUpperCase().toCharArray( );
}
}
String[] search = sb.toString().split("\n");
initLetterArray(search);
reader.close();
}
protected void initLetterArray(String[] letterLines) {
char[][] array = new char[letterLines.length][];
System.out.print("Letter Lines are " +letterLines.length );
for (int i = 0; i < letterLines.length; i++) {
letterLines[i] = letterLines[i].replace(" ", "").toUpperCase();
array[i] = letterLines[i].toCharArray();
}
System.out.print("Array inatoshana ivi " + array.length);
pz.init(array);
}
}
提前致谢。
最佳答案
就是这里!
char[][] array = new char[letterLines.length][];
您仅初始化一个轴。
当您将此数组传递给 init() 并设置 this.letterArray = letterArray; 时，letterArray 也未完全初始化。
尝试为两个轴添加长度:
char[][] array = new char[letterLines.length][LENGTH];
关于java - 数组上的 Wordsearch 难题 nullpointerException，我们在Stack Overflow上找到一个类似的问题： https://stackoverflow.com/questions/21405134/