Type Mismatch: 无法将 double 转换为 double[]

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英文:

Type Mismatch: Can't convert double into double[]

问题

当我运行这段Java代码时,出现了错误。我是Java的新手。有人可以帮忙吗?

package raza.project.arrays;
import java.util.*;

public class arraysLearning {

public static void main(String[] args) {
  int [] numbers = { 25,36,38,63,89,52,74};
  double[] med = median(numbers);
}

// 返回一个数组中的中位数值,不改变参数数组
public static double median(int[] numbers) {
 int[] tmp = Arrays.copyOf(numbers, numbers.length);
 Arrays.sort(tmp);
 int mid = tmp.length/2; // 注意:整数除法
 if (tmp.length%2 == 0) { // 偶数长度?
 return (tmp[mid-1]+tmp[mid])/2.0; // 浮点数除法
 }
  else {
     return tmp[mid];
     }
  }
}

Java编译器是最新的JDK14

英文:

When i am running this java code i got error. I am new to java. Can anyone help.


package raza.project.arrays;
import java.util.*;
public class arraysLearning {

public static void main(String[] args) {
  int [] numbers = { 25,36,38,63,89,52,74};
  double[] med = median(numbers);
}
  //Return the median value of an array of numbers
//without changing the parameter array
public static double median(int[] numbers) {
 int[] tmp = Arrays.copyOf(numbers, numbers.length);
 Arrays.sort(tmp);
 int mid = tmp.length/2; // Note: int division
 if (tmp.length%2 == 0) { // even length?
 return (tmp[mid-1]+tmp[mid])/2.0; //float division
 }
  else {
     return tmp[mid];
     }
  }
}

java compiler is latest jdk14

答案1

得分: 2

这个方法:public static double median(int[] numbers) 返回一个 double 类型的对象。

当你想调用一个方法并将结果存储在一个变量中时,你需要确保变量的类型与方法返回的类型相同。

你需要更改这行代码:

double[] med = median(numbers);

double med = median(numbers);

在这里,变量的类型是 double,而方法返回一个 double。两者类型匹配,编译器满意,你的代码可以编译。但在你的情况下,类型是 double[],而方法返回一个 double 对象... 没有匹配,所以你的代码无法编译。

英文:

This method: public static double median(int[] numbers) returns an object of type double.

When you want to call a method a get the result in a variable, you need to make sure the variable is of the same type as the type returned by the method.

You need to change this line:

double[] med = median(numbers);

With

double med = median(numbers);

Here, the variable is of type double and the method returns a double. Both types matches, the compiler is happy and your code compiles. But in your case, the type is double[] and the method returns a double object... There is no match, so your code doesn't compile

答案2

得分: 0

Your median() method is supposed to return a "double" value and not an array of double values.

public static void main(String[] args) {
  int[] numbers = {25, 36, 38, 63, 89, 52, 74};
  double med = median(numbers); // remove [] on this line.
}
英文:

Your median() method is supposed to return a "double" value and not an array of double values.

public static void main(String[] args) {
  int[] numbers = {25,36,38,63,89,52,74};
  double med = median(numbers); // remove [] on this line.
}

答案3

得分: 0

You are returning a double value but you are returning it to a double array, there is type mismatch.

你返回一个 double 值,但你将它返回给一个 double 数组,类型不匹配。

英文:

You are returning a double value but you are returning it to a double array, there is type mismatch.

import java.util.*;
public class Test {

public static void main(String[] args) {
    int [] numbers = { 25,36,38,63,89,52,74};
    double med = median(numbers);
}
//Return the median value of an array of numbers
//without changing the parameter array
public static double median(int[] numbers) {
    int[] tmp = Arrays.copyOf(numbers, numbers.length);
    Arrays.sort(tmp);
    int mid = tmp.length/2; // Note: int division
    if (tmp.length%2 == 0) { // even length?
        return (tmp[mid-1]+tmp[mid])/2.0; //float division
    }
    else {
        return tmp[mid];
    }
}

}

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  • 本文由 发表于 2020年7月28日 16:30:28
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