如何修复 "variable phraseLength might not have been initialized" (Java)？

Question

我是编程新手 Java，正在处理涉及字符串的作业。我刚开始使用代码模板，我的指示是编译它并查看输出，但出现 "variable phraseLength might not have been initilized" 错误。它指的是我在代码底部附近使用 "phraseLength" 作为变量的时间。有谁知道如何解决这一问题？非常感谢你提前。

import java.util.Scanner;
public class Working_With_Strings
{
public static void main (String[] args)
{
//instantiate the String……
String phrase = new String ("This is a String test.");
int phraseLength;
int middle3;// number of characters in the phrase String
int middleIndex;    // index of the middle character in the String
String firstHalf;   // first half of the phrase String
String secondHalf;  // second half of the phrase String
String switchedPhrase; // a new phrase with original halves switched

// 1-compute the length and middle index of the phrase


//2- get the substring for each half of the phrase


//3- concatenate the firstHalf at the end of the secondHalf


    // print information about the phrase
    System.out.println();
    System.out.println ("Original phrase: " + phrase);
    System.out.println ("Length of the phrase: " + phraseLength +
                " characters");
    System.out.println ("Index of the middle: " + middleIndex);
    System.out.println ("Character at the middle index: " + 
                phrase.charAt(middleIndex));
    System.out.println ("Switched phrase: " + switchedPhrase);

    System.out.println();
    }
}

一开始没看懂报错是什么意思，因为不知道初始化是什么意思。现在我知道我需要用一个值来初始化 "phraseLength" 。再次感谢您的帮助！

Answer 1

int phraseLength;
int middle3;// number of characters in the phrase String
int middleIndex;    // index of the middle character in the String
String firstHalf;   // first half of the phrase String
String secondHalf;  // second half of the phrase String
String switchedPhrase; // a new phrase with original halves switched

至：

int phraseLength = 0;
int middle3 = 0;// number of characters in the phrase String
int middleIndex = 0;    // index of the middle character in the String
String firstHalf = "";   // first half of the phrase String
String secondHalf = "";  // second half of the phrase String
String switchedPhrase = ""; // a new phrase with original halves switched

你应该在使用它们之前初始化变量...我向你推荐一本书Head First Java

Answer 2

方法中声明的变量不能自动初始化。
也许你需要阅读一些关于java基础的基础书籍。

int phraseLength = 0;
int middle3 = 0;// number of characters in the phrase String
int middleIndex = 0;    // index of the middle character in the String
String firstHalf = null;   // first half of the phrase String
String secondHalf = null;  // second half of the phrase String
String switchedPhrase = null;

Answer 3

你已经声明了一个变量但没有初始化变量

int phraseLength;

这里你试图访问一个未初始化的变量。

System.out.println ("Length of the phrase: " + phraseLength +
                " characters");

您必须先定义变量的值，然后才能访问该值：

您的情况有两种解决方案：

1.You 应该在如下声明后初始化变量：

`int phraseLength;//Declaration
pharaseLength = 0;`//Initialization

2.Assign这个变量经过一些计算：

这里我取字符串的长度赋值给变量

  pharaseLength = pharaseString.length();

您需要对其余变量执行相同的操作

供您参考：

Initialization , assignment ,declaration:之间的区别

Answer 4

`     import java.util.Scanner;
     public class Working_With_Strings
    {
    public static void main (String[] args)
    {
    //instantiate the String……
    String phrase = new String ("This is a String test.");
    int phraseLength;
    phraseLength=phrase.length();
    System.out.println ("Original phrase: " + phrase);
    System.out.println ("Length of the phrase: " + phraseLength +
                " characters");

    }
    }     

           `

如何修复 "variable phraseLength might not have been initialized" (Java)？

How to fix a "variable phraseLength might not have been initialized" (Java)?

java

string

phrase