在 Java 中从一种方法调用 String 到另一种方法
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Call String from one method to another in Java
提问by James
sorry if this is a simple question but I have been trying for quite a while now is it possible to call a string from one method to another...
抱歉，如果这是一个简单的问题，但我已经尝试了很长时间了，现在是否可以将字符串从一种方法调用到另一种方法...
Below I want to call the string fileNamefrom the method fileNameto fileOutputToFile. I know I can pass it in but I want to call it from fileOutputToFile.
下面我想fileName从方法中调用字符串fileName到fileOutputToFile. 我知道我可以传入它，但我想从fileOutputToFile.
public class outputToFile {
public void fileName(){
String fileName = "Test";
}
public void fileOutputToFile(String hex) throws Exception{
String fileInfo = hex;
try {
PrintWriter out = new PrintWriter(new BufferedWriter(
new FileWriter("myfile.txt", true)));
out.print(fileInfo);
out.print("\n");
out.close();
}catch (IOException e){
}
}
}
回答by coobird
It's not possible to call a local variable which is in another method -- it's an issue of scope.
不可能调用另一个方法中的局部变量——这是一个范围问题。
Therefore, it is not possible to retrieve the fileNamevariable from the fileName()method from the fileOutputToFilemethod.
因此，不可能fileName从fileName()方法中检索方法中的变量fileOutputToFile。
One way to "retrieve" the file name would be to returnthe file name when the fileNamemethod is called:
“检索”return文件名的fileName一种方法是调用该方法时的文件名：
public String getFileName(){
String fileName = "Test";
return fileName;
}
(Note: I've taken the liberty to rename the method to something that would be closer to the conventions for naming identifiers in Java.)
（注意：我冒昧地将方法重命名为更接近 Java 中命名标识符的约定。）
Then, in the fileOutputToFilemethod, the getFileNamemethod can be called to retrieve the value of the fileName.
然后，在fileOutputToFile方法中，getFileName可以调用该方法来检索 的值fileName。
It should be noted that in this case, it may actually be better to just use an field (an instance or class variable) rather than calling a separate method to retrieve a file name. Considering the method is just returning a constant String, a field could hold the value:
应该注意的是，在这种情况下，实际上只使用字段（实例或类变量）而不是调用单独的方法来检索文件名实际上可能更好。考虑到该方法只是返回一个 constant String，一个字段可以保存该值：
public class OutputToFile {
// Here, we use a class variable.
private static final String FILE_NAME = "Test";
public void fileOutputToFile(String hex) {
// use FILE_NAME field here.
}
}
回答by jbrookover
All variables have scope that is generally limited to the {} enclosure that they are in. So, if you create a variable in one method, it is not accessible in another method unless you pass it in.
所有变量的范围通常仅限于它们所在的 {} 外壳。因此，如果您在一个方法中创建一个变量，则除非您将其传入，否则无法在另一种方法中访问它。
The good news is you can create class level variables that are shared by all methods within a class!
好消息是您可以创建类中所有方法共享的类级变量！
public class OutputToFile {
private String fileName = "Test";
public void fileName() {
System.out.println(fileName);
fileName = "Something Different"
}
public void fileOutputToFile(String hex) {
System.out.println(fileName);
// Do other things with it
}
}
回答by Coleman S
If I understand you correctly, you wish to returna string from fileName().
如果我理解正确，您希望从 fileName()返回一个字符串。
Currently, your implementation of fileName() does nothing. You must add a return statement to return a value: 'return "Test"'
目前，您对 fileName() 的实现什么都不做。您必须添加一个 return 语句来返回一个值：'return "Test"'
