最终变量可能已被分配 [英] Final variable may already have been assigned

问题描述

我正在编写一个有两个我想使用的最终变量的程序，我需要在我实际运行该类的时候设置它们，因为它们可能是不同的。

我有初始化与任何其他类变量相同，我希望在初始化名称和类型但不是值时使用。

  public final String filename，filepath; 
  

在构造函数中，我设置的值如下

  public myClass（String value）{
 this.filename = value; 
 this.filepath = anotherPartOfValue; 
} 
  

当我这样做，我得到一个警告，最后的字段[x ]可能已经被分配了

有没有办法避免此警告，仍然保持最终状态并在构造函数中设置值？

我正在使用eclipse btw。

---

编辑：

这是给我错误的确切代码

  import java.io. *; 
 
 public class Dirt {
 
 private String [] tables; 
 private int numTables; 
 private final String filename，filepath; 
 
 public Dirt（String file）{
 this.tables = new String [0]; 
 this.numTables = 0; （int i = file.length（）; i< 0; i--）{
 if（file.charAt（i）=='/'）{
 this.filename = file.substring（i）; 
 this.filepath = file.substring（1，i-1）; 
} 
} 
} 
  

}

解决方案

问题是你在一个循环中分配给最终的变量。没有什么可以阻止循环循环多次，并且如果条件不止一次被满足。 （如果文件中有两个/字符，那么会发生什么？/ / code>？还是没有？）

是在构造函数中使用临时String变量，然后将它们分配给最终的 filename 和 filepath ：

  public Dirt（String file）{
 this.tables = new String [0]; 
 this.numTables = 0; 
 String name = null; 
 String path = null; （int i = file.length（）; i< 0; i--）{
 if（file.charAt（i）=='/'）{
 name = file.substring（i）; 
 path = file.substring（1，i-1）; 
 //需要休息吗？ 
} 
} 
 this.filename = name; 
 this.filepath = path; 
} 
  

这是丑陋的，但这是一个简单的方法来确定 filename 和 filepath 一定会被分配，绝对只能分配一次。

I am writing a program that has two final variables that I wish to use, I need these to be set at the time that I actually run the class because they are likely to be different each instance.

I have the initialization the same as any other class variable I wish to use where I initialize a name and type but not a value.

   public final String filename, filepath;

In the Constructor I set the values as follows

 public myClass(String value) {
     this.filename = value;
     this.filepath = anotherPartOfValue;
  }

When I do this, I get a warning that "The final field [x] may have already been assigned"

Is there a way to avoid this warning and still keep the final state and set the value in the constructor?

I am using eclipse btw.

---

Edit:

This is the exact code that gives me the error

import java.io.*;

public class Dirt {

private String[] tables;
private int numTables;
private final String filename, filepath;

public Dirt(String file) {
    this.tables = new String[0];
    this.numTables = 0;

    for (int i = file.length(); i < 0; i--) {
        if (file.charAt(i) == '/') {
            this.filename = file.substring(i);
            this.filepath = file.substring(1, i-1);
        }
    }
}

}

解决方案

The problem is that you are assigning to the final variables in a loop. There's nothing to prevent the loop from looping more than once and the if condition being satisfied more than once. (What happens if there are two '/' characters in file? Or none?)

One way around this is to use temporary String variables in the constructor and then assign them to filename and filepath at the end:

public Dirt(String file) {
    this.tables = new String[0];
    this.numTables = 0;
    String name = null;
    String path = null;

    for (int i = file.length(); i < 0; i--) {
        if (file.charAt(i) == '/') {
            name = file.substring(i);
            path = file.substring(1, i-1);
            // need a break here?
        }
    }
    this.filename = name;
    this.filepath = path;
}

It's ugly, but it's a straightforward way to know for sure that filename and filepath will definitely be assigned and definitely be assigned only once.

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