问题描述
第一个 for 循环将正确的系数和指数值打印为 由值字符串提供,但第二个 for 循环将 addLink 方法没有打印正确的值?我看不到什么 问题是。为什么第一个 for 循环的输出与第二个循环的输出不匹配?
代码已被编辑。我已将 addLink 方法移到第一个 for 循环中,我的输出如下所示。这仍然不是我想要的。
public class polyvalues {
Term head;
public polyvalues() {
String value = "5 6 8 9 1 9";
String sub[] = value.split(" ");
double coeff = 0;
int exp = 0;
for (int i = 0; i < sub.length; i++)
{
if (sub[i].isEmpty()) {
System.out.println("No input");
}
if (i % 2 == 0) {
try {
coeff = Double.parseDouble(sub[i]);
System.out.println("Coeff is " + coeff);
} catch (NumberFormatException e) {
System.out.println("Fix This");
}
} else {
try {
exp = Integer.parseInt(sub[i]);
System.out.println("The exp is " + exp);
} catch (NumberFormatException e) {
System.out.println("Fix This");
}
}
this.addLink(coeff,exp);//moved from commented out for-loop
}
System.out.println("*******************************************");
/*for (int i = 0; i < sub.length; i++)
{
this.addLink(coeff,exp);
}*/
}//end constructor
public void addLink(double a,int b)
{
if(head == null)
{
head = new Term(a,b);
return;
}
Term currNode = head;
while(currNode.next != null)
{
currNode = currNode.next;
}
currNode.next = new Term(a,b);
//addLink(a,b);
}
static class Term{
double coeff;
int exp;
Term next;
Term(double c,int e){
this.coeff = c;
this.exp = e;
this.next = null;
System.out.println("The Coeff "+ this.coeff);
System.out.println("The Exp "+ this.exp);
}
}
public static void main(String[] args)
{
polyvalues p1 = new polyvalues();
}
} //end of class
现在,当我将 addLink 方法移动到第一个 for 循环时,我得到了这个。为什么我打印时会得到这些重复的输出?
当这是我想要的时: 是我的节点吗?
解决方法
因为在第二个循环中,您每次都传递相同的 coeff
和 exp
值。
在第一个循环结束时,coeff
的值为 1.0,exp
为 9
并且您每次都将相同的值传递给方法 addLink
。
要解决它,要么创建一个数组来存储每个值,要么在第一个循环中调用 addLink
。
您确实需要学习如何调试代码。每个程序员都需要知道如何调试代码。你读过这个网页吗? How to debug small programs
无论如何,如果您使用的是 IDE(如 Eclipse 或 IntelliJ),那么它应该有一个调试器,您应该学会使用它。
您的代码已经很接近了。您只需要将调用移动到方法 addLink
。 (请参阅下面的代码。)如果您使用调试器单步调试代码,您就会明白为什么。基本上,您需要在获得 addLink
和 coeff
的值后调用 exp
。在您的代码中,您将调用 addLink
两次 - 一次是您只有 coeff
值,第二次是您同时拥有 coeff
和 exp
。
在下面的代码中,我用注释表示了更改Moved from after this 'else' block.我也保留了原始行,但已将其注释掉。
另请注意,我添加了 [覆盖] toString 方法只是为了更容易查看执行代码的结果。
public class Polyvalues {
Term head;
public Polyvalues() {
String value = "5 6 8 9 1 9";
String sub[] = value.split(" ");
double coeff = 0;
int exp = 0;
for (int i = 0; i < sub.length; i++) {
if (sub[i].isEmpty()) {
System.out.println("No input");
}
if (i % 2 == 0) {
try {
coeff = Double.parseDouble(sub[i]);
System.out.println("Coeff is " + coeff);
}
catch (NumberFormatException e) {
System.out.println("Fix This");
}
}
else {
try {
exp = Integer.parseInt(sub[i]);
System.out.println("The exp is " + exp);
this.addLink(coeff,exp); // Moved from after this 'else' block.
}
catch (NumberFormatException e) {
System.out.println("Fix This");
}
}
//this.addLink(coeff,exp);//moved from commented out for-loop
}
System.out.println("*******************************************");
}// end constructor
public void addLink(double a,int b) {
if (head == null) {
head = new Term(a,b);
return;
}
Term currNode = head;
while (currNode.next != null) {
currNode = currNode.next;
}
currNode.next = new Term(a,b);
// addLink(a,b);
}
public String toString() {
StringBuilder sb = new StringBuilder();
Term curr = head;
while (curr != null) {
sb.append(curr);
curr = curr.next;
}
return sb.toString();
}
static class Term {
double coeff;
int exp;
Term next;
Term(double c,int e) {
this.coeff = c;
this.exp = e;
this.next = null;
System.out.println("The Coeff " + this.coeff);
System.out.println("The Exp " + this.exp);
}
public String toString() {
return String.format("[C=%.2f,E=%d]-> ",coeff,exp);
}
}
public static void main(String[] args) {
Polyvalues p1 = new Polyvalues();
System.out.println(p1);
}
} // end of class
运行上面的代码打印如下:
Coeff is 5.0
The exp is 6
The Coeff 5.0
The Exp 6
Coeff is 8.0
The exp is 9
The Coeff 8.0
The Exp 9
Coeff is 1.0
The exp is 9
The Coeff 1.0
The Exp 9
The Coeff 1.0
The Exp 9
*******************************************
[C=5.00,E=6]-> [C=8.00,E=9]-> [C=1.00,E=9]->