英文:
Java outputting different row numbers for each output
问题
我有这段代码，它会打印出我拥有的每一行的最大值。但是，我也遇到了打印出每个输出的行号的问题。我尝试使用变量 i 来为每一行加 1。显然，这个方法不起作用，只是想展示一下我的尝试。如果没有 i，该代码可以正常工作，用于查找文本文件中字符串的最大值。如果有其他方法可以更改每个输出的行号，将不胜感激。例如：
Row 1: 5
Row 2: 67
Row 3: 43
这是我想要的。我已经尝试过的只有：
Row 1: 5
Row 1: 67
Row 1: 43
我的 Java 代码如下：
import java.util.Scanner;
import java.io.File;
public class maxValue {
public static void main(String[] args) throws Exception {
int i = 0;
String fileName = "C:\\Users\\Michael\\Documents\\input.csv";
File f = new File(fileName);
Scanner fileScan = new Scanner(f);
while (fileScan.hasNext()) {
String line = fileScan.nextLine();
i++; // 增加行号
System.out.println("Row " + i + ": " + (extractMaximum(line)));
}
fileScan.close();
}
static int extractMaximum(String str) {
int num = 0;
int res = 0;
// 开始遍历给定的字符串
for (int i = 0; i < str.length(); i++) {
// 如果出现数字，开始将其转换为整数，直到出现非数字字符
if (Character.isDigit(str.charAt(i)))
num = num * 10 + (str.charAt(i) - '0');
// 更新最大值
else {
res = Math.max(res, num);
// 重置数字
num = 0;
}
}
// 返回最大值
return Math.max(res, num);
}
}
现在你的代码应该能够正确打印出每一行的最大值，并且带有正确的行号。
英文:
I have this code that prints out the max value of each row I have. But I am having trouble also printing out the row number for each output.I tried using i to add 1 to each row. Obviously this does not work with it, just wanted to show my attempt. Without the i the code works fine for finding the max value of my string from a text file. If there is another way to change my row number for each output it would be much appreciated. For example,
<pre>
Row 1: 5
Row 2: 67
row 3: 43
</pre>
is what i want. All i have been able to get is:
<pre>
Row 1: 5
Row 1: 67
row 1: 43
</pre>
My java code
import java.util.Scanner;
public class maxValue {
public static void main(String[] args) throws Exception {
int i=0;i<3;i++;
String fileName="C:\\Users\\Michael\\Documents\\input.csv";
File f = new File(fileName);
Scanner fileScan= new Scanner(f);
while(fileScan.hasNext()) {
String line=fileScan.nextLine();
System.out.println("ROW " + i + ": " + (extractMaximum(line)));
}
fileScan.close();
}
static int extractMaximum(String str) {
int num = 0;
int res = 0;
// Start traversing the given string
for (int i = 0; i<str.length(); i++) {
// If a numeric value comes, start converting
// it into an integer till there are consecutive
// numeric digits
if (Character.isDigit(str.charAt(i)))
num = num * 10 + (str.charAt(i)-'0');
// Update maximum value
else {
res = Math.max(res, num);
// Reset the number
num = 0;
}
}
// Return maximum value
return Math.max(res, num);
}
}
答案1
得分: 1
你需要在循环中增加 i 的值：
public static void main(String[] args) throws Exception
{
String fileName = "C:\\Users\\Michael\\Documents\\input.csv";
File f = new File(fileName);
Scanner fileScan = new Scanner(f);
// 一个选项：使用 for 循环
for (int i = 1; fileScan.hasNext(); i++) {
String line = fileScan.nextLine();
// 我更喜欢使用 printf
System.out.printf("ROW %d: %d%n", i, extractMaximum(line));
}
fileScan.close();
}
// 重写以使用流
// 即使你不想使用流，
// 使用正则表达式拆分字符串也是一种改进
static int extractMaximum(String str)
{
return Arrays.stream(str.split("\\D+"))
.map(x -> Integer.parseInt(x))
.max(Integer::compare)
.get();
}
英文:
You need to increment i in the loop:
public static void main(String[] args) throws Exception
{
String fileName="C:\\Users\\Michael\\Documents\\input.csv";
File f = new File(fileName);
Scanner fileScan = new Scanner(f);
// One option: a for loop
for (int i = 1; fileScan.hasNext(); i++) {
String line = fileScan.nextLine();
// I prefer printf
System.out.printf("ROW %d: %d%n", i, extractMaximum(line));
}
fileScan.close();
}
// Re-written to use streams
// Even if you don't want to use stream,
// Using the regex to split the string is an improvement
static int extractMaximum(String str)
{
return Arrays.stream(str.split("\\D+"))
.map(x -> Integer.parseInt(x))
.max(Integer::compare)
.get();
}
</details>
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