我应该如何处理ArrayIndexOutOfBound异常?

时间:2019-01-16 19:47:03

标签: java arrays indexoutofboundsexception wordsearch

对于单词搜索程序,我将二十个单词输入到数组列表中,然后将此单词数组列表转换为一维数组。我有一个名为createWordSearch(words)的方法,其中words是一维数组。

还有一些其他方法可以帮助在此方法中创建整个单词搜索,例如location(wordArr,word,dir,pos),placeWord(wordArr,word),placeMessage(wordArr,消息)。我在location方法中有一个ArrayIndexOutOfBound异常,特别是在if ((DIRECTIONS[dir][0] == 1 && (word.length() + c) > cols)处。

for (int dir = 0; dir < DIRECTIONS.length; dir++) { dir = ( (dir) + (randDirection) % DIRECTIONS.length);int randDirection = rand.nextInt(DIRECTIONS.length);public static final int[][] DIRECTIONS = {{1,0}, {0,1}, {1,1}, {1,-1}, {-1,0}, {0,-1}, {-1,-1}, {-1,1}};的地方

我试图理解为什么会有这个异常,但是我不能t pinpoint exactly where, which is why I am having trouble fixing my code. I am assuming the error happens because of that for loop for dir listed above, but I不太确定。

// Create a method that places the word letters at a certain location
	
	public static int location (WordArray wordArr, String word, int dir, int pos) {    		
		int r = ( (pos) / (cols)); // Where r = row
		int c = ( (pos) / (cols)); // Where c = column    		
		// Checking the bounds...    	
		if ((DIRECTIONS[dir][0] == 1 && (word.length() + c) > cols)
				|| (DIRECTIONS[dir][0] == -1 && (word.length() - 1) > c)
				|| (DIRECTIONS[dir][1] == 1 && (word.length() + r) > rows)
				|| (DIRECTIONS[dir][1] == -1 && (word.length() - 1) > r)    				
				)     			
			return 0;    			
			int i, cc, rr, overLaps = 0;    			
			// Checking the cells...    			
			for (i = 0, rr = r, cc = c; i < word.length(); i++) {    				
				if (rr < rows && cc < cols && i < word.length()) {    					
					return 0;    					
				}//end of if    				
				cc += DIRECTIONS[dir][0];
				rr += DIRECTIONS[dir][1];    				
			}//end of for loop   			
			// Placing the word...    			
			for (i = 0, rr = r, cc = c; i < word.length(); i++) {    				
				if (rr < rows && cc < cols && i < word.length()) {    					
					overLaps++;    					
				}//end of if    				
				if (i < word.length() - 1) {    					
					cc += DIRECTIONS[dir][0];
					rr += DIRECTIONS[dir][1];    					
				}//end of inner if    				
			}//end of for loop 2    			
			int lettersPlaced = ( (word.length()) - (overLaps));    			
			if (lettersPlaced > 0)     				
				wordArr.solutions.add(String.format("%-10s (%d,%d)(%d,%d)", word, c, r, cc, rr));
			return lettersPlaced;    		
	}//end of location(wordArr,word,dir,pos)

1 个答案:

答案 0 :(得分:1)

我的猜测是,它会导致您仅对分配值的一部分而不是全部进行模运算:

for (int dir = 0; dir < DIRECTIONS.length; dir++) 
{ 
    dir = ( (dir) + (randDirection) % DIRECTIONS.length);
}

应该是:

for (int dir = 0; dir < DIRECTIONS.length; dir++) 
{ 
    dir = ( (dir) + (randDirection) ) % DIRECTIONS.length;
}

一些关键说明,问题的格式不太好-格式应将问题分为关键部分,为我们提供一种简单的方式来准确了解您要问的内容,并应格式化所有代码部分以区别他们从其余的。

您可能还应该阅读有关重构的信息-在这一天,编译器格式化我们的代码并向我们确切说明每个块的开始和结束位置-确实不需要在每个括号的末尾加注释。

给变量赋予有意义的名称,例如r,rr,c,cc​​,这对于不知道您的代码应该做什么的人来说是很困惑的。

您还可以将部分代码提取到单独的方法中,以使其更加清晰。

在终点

for (i = 0, rr = r, cc = c; i < word.length(); i++) {                   
    if (rr < rows && cc < cols && i < word.length()) { 

此检查是多余的,可以更改为

for (i = 0, rr = r, cc = c; i < word.length(); i++) {                   
    if (rr < rows && cc < cols) {