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运行程序时出现NullPointerException错误,我无法弄清楚原因。确切的错误是在EditDistance.main(EditDistance.java:19)在EditDistance.editDistance(EditDistance.java:32)在线程异常 “主” 显示java.lang.NullPointerException 运行Java程序时出现NullPointerException错误
import java.util.ArrayList;
public class EditDistance
{
public static void main(String[] args)
{
ArrayList<Character> a = new ArrayList<Character>();
char[] xArray = null;
char[]yArray = null;
char[] finalY = null;
String x = "AACAGTTACC";
String y = "TAAGGTCA--";
xArray = x.toCharArray();
yArray = y.toCharArray();
a = toArrayList(a , yArray);
System.out.println(editDistance(a, xArray, finalY, y));
}
public static int editDistance(ArrayList<Character> a, char[] xArray, char[] finalY, String y)
{
int temp;
for(int i = 0; i<xArray.length; i++)
{
temp = y.indexOf(xArray[i]);
if(temp != -1)
{
finalY[i] = a.get(temp);
a.remove(temp);
y = (y.substring(0, temp) + y.substring(temp));
}
else if(y.indexOf(xArray[i])==-1)
{
xArray[i]='z';
}
}
for(int j =0; j<xArray.length; j++)
{
if(xArray[j]=='z')
{
finalY[j]=a.get(j);
}
}
int result = calcScore(finalY, xArray);
return result;
}
public static ArrayList<Character> toArrayList(ArrayList<Character> a, char[] yArray)
{
for(int i=0; i<yArray.length;i++)
{
a.add(yArray[i]);
}
return a;
}
public static int calcScore(char[] finalY, char[] xArray)
{
int number = 0;
for(int i=0; i <xArray.length; i++)
{
if(finalY[i]==(xArray[i]))
{
}
else if(finalY[i] == '-')
{
number++;
number++;
}
else if (finalY[i] != xArray[i])
{
number++;
}
}
return number;
}
}
任何帮助理解
哪一行是32行? –
您应该用错误标记行,以便更容易发现。 – Lycha
计算上算法很糟糕,您应该尝试使用更高性能的数据结构来编写它。也许不仅仅是一个数组列表你需要一个hashmap? –