我一直在研究一个程序，该程序读取一个文件，然后找到所有X，并将它们返回为0，以便可以在完整程序中使用它。
到目前为止，我在正确转换为字符串方面遇到许多问题。我目前收到错误消息:
线程“主”中的异常java.lang.Error: Unresolved 编译问题:
此方法必须返回String类型的结果
这是我的代码:
import java.io.BufferedReader;
import java.io.File;
import java.io.FileReader;
import java.io.IOException;
import java.util.Scanner;
public class ReadMagicSquare {
public static String Replace(String filename) {
try {
Scanner file = new Scanner(new File(filename));
System.out.println(file);
StringBuilder b = new StringBuilder();
String s = "";
int n = 0;
while(file.hasNextLine()){
s = file.nextLine();
n++;
if (s == "X") {
s = "0";
b.append(s).append(System.getProperty("line.separator"));
return b.toString();
} else {
return b.toString();
}
}
} catch (Exception e) {
}
}
static int[][] matrix;
int size = -1;
int log10 = 0;
String numberFormat;
public ReadMagicSquare(String filename) {
try {
readFile("test1.txt");
} catch (IOException e) {
e.printStackTrace();
}
}
public void readFile(String filename) throws IOException {
BufferedReader John= new BufferedReader(new FileReader("test1.txt"));
String line;
int j = 0;
while ((line = John.readLine()) != null) {
String[] vals = line.trim().split("\\s+");
if (matrix == null) {
size = vals.length;
matrix = new int[size][size];
log10 = (int) Math.floor(Math.log10(size * size)) + 1;
numberFormat = String.format("%%%dd", log10);
}
for (int i = 0; i < size; i++) {
matrix[j][i] = Integer.parseInt(vals[i]);
}
j++;
}
}
public String toString() {
StringBuffer John1 = new StringBuffer();
if (matrix != null) {
for (int j = 0; j < size; j++) {
John1.append(" ");
for (int i = 0; i < size; i++) {
John1.append(String.format(numberFormat, matrix[j][i]));
}
if (j < size - 1) {
John1.append("\n");
} else {
John1.append("");
}
}
}
return John1.toString();
}
public static void main(String[] args) {
Replace("test1.txt");
ReadMagicSquare square = new ReadMagicSquare("square.txt");
System.out.println(square.toString());
System.out.println(matrix[3][0]);
}
}
你们当中有人知道原因吗？谢谢你的时间!
编辑:
非常感谢您的投入!我进行了以下更改，但仍然有问题:
public static String Replace(String filename) {
try {
Scanner file = new Scanner(new File(filename));
System.out.println(file);
StringBuilder b = new StringBuilder();
String s = "";
int n = 0;
while(file.hasNextLine()){
s = file.nextLine();
n++;
if (s.equals("X")) {
s = "0";
b.append(s).append(System.getProperty("line.separator"));
b.toString();
} else {
return b.toString();
}
}
} catch (Exception e) {
return null;
}
try (PrintStream out = new PrintStream(new FileOutputStream("test1,1.txt"))) {
out.print(b);
}
}
我现在对out.print(b)有问题；线。它给了我错误:
b无法解析为变量
这对我来说是新的。有人愿意详细说明吗？
编辑2:
现在，我已经解决了大多数问题，但是当我尝试运行该程序时，它不会更改.txt文件中的X。我得到相同的输出，而我希望所有X都变为0。我现在有以下代码:
import java.io.BufferedReader;
import java.io.File;
import java.io.FileOutputStream;
import java.io.FileReader;
import java.io.IOException;
import java.io.PrintStream;
import java.util.Scanner;
public class ReadMagicSquare {
static int[][] matrix;
int log10 = 0;
String numberFormat;
String line;
int j = 0;
int size = 0;
public static String Replace(String filename) {
try {
Scanner file = new Scanner(new File(filename));
System.out.println(file);
StringBuilder b = new StringBuilder();
String s = "";
while(file.hasNextLine()){
s = file.nextLine();
if (s.equals("X")) {
s = "0";
b.append(s).append(System.getProperty("line.separator"));
} else {
b.append(s).append(System.getProperty("line.separator"));
}
}
try (PrintStream out = new PrintStream(new FileOutputStream("test1,1.txt"))) {
out.print(b);
out.close();
} catch (IOException e) {
}
} catch (Exception e) {
System.out.println("Problem reading file.");
}
return "bobby";
}
public ReadMagicSquare(String filename) {
try {
readFile("test1,1.txt");
} catch (IOException e) {
e.printStackTrace();
}
}
public void readFile(String filename) throws IOException {
BufferedReader buffer = new BufferedReader(new FileReader("test1,1.txt"));
while ((line = buffer.readLine()) != null) {
String[] vals = line.trim().split("\\s+");
if (matrix == null) {
size = vals.length;
matrix = new int[size][size];
log10 = (int) Math.floor(Math.log10(size * size)) + 1;
numberFormat = String.format("%%%dd", log10);
}
for (int i = 0; i < size; i++) {
matrix[j][i] = Integer.parseInt(vals[i]);
}
j++;
}
}
public String toString() {
StringBuffer buff = new StringBuffer();
if (matrix != null) {
for (int j = 0; j < size; j++) {
buff.append(" ");
for (int i = 0; i < size; i++) {
buff.append(String.format(numberFormat, matrix[j][i]));
}
if (j < size - 1) {
buff.append("\n");
} else {
buff.append("");
}
}
}
return buff.toString();
}
public static void main(String[] args) {
Replace("test1.txt");
ReadMagicSquare square = new ReadMagicSquare("square.txt");
System.out.println(square.toString());
System.out.println(matrix[3][0]);
}
}
有人知道导致问题的原因吗？
最佳答案
I now have issues with the out.print(b); line. It gives me the error:
b cannot be resolved to a variable
which is new to me. Would anyone care to elaborate?
那是因为您不能访问catch块中try块内部声明的变量，只需将变量声明移到try块之前(您仍然可以在try块内部对其进行初始化)。
这是同一问题的另一个答案https://stackoverflow.com/a/2854153/1935341
关于java - 读取.txt文档并在Java中进行编辑时出现问题，我们在Stack Overflow上找到一个类似的问题： https://stackoverflow.com/questions/34645714/