Java靜態方法和使用數組計算

Question

我試圖計算和顯示陣列我的程序，但它口口聲聲說像你不能轉換雙爲雙[]，例如，在我的代碼，當我計算表面重力，它說，我不喜歡有一個數組和可變的混合，因爲我聲明瞭萬有引力常數作爲變量，一切公式作爲數組中的其他。另一個是當我除以2的直徑陣列計算半徑，並通過半徑變量作爲用於計算表面重力的靜態方法的參數時，編譯器說，一個雙不能被轉換爲雙[]因爲在用於表面重力的靜態方法，我聲明瞭半徑爲一個數組。任何幫助將不勝感激。以下是我的代碼：

public class GravityV1{ 

// calculate surface gravity static method 
public static double surfaceGravity(double G, double[] M, double[] r){ 

    // equation for surface gravity 
    double[] g = (G * M)/Math.pow(r, 2); 

    // return statement 
    return g; 
} 

// displaying static method 
public static void display(String[] planets, double[] radius, double[] 
     mass, double[] g){ 

    // display output 
    System.out.printf("%n", planets, radius, mass, g); 
} 

// write results to text file static method 


public static void main(String args[]){ 

    // declare array for months 
    String[] Planets = new String[8]; 

    // initialize array 
    Planets [0] = "Mercury"; 
    Planets [1] = "Venus"; 
    Planets [2] = "Earth"; 
    Planets [3] = "Mars"; 
    Planets [4] = "Jupiter"; 
    Planets [5] = "Saturn"; 
    Planets [6] = "Uranus"; 
    Planets [7] = "Neptune"; 

    // declare array for mass 
    double[] mass = new double[8]; 

    // initialize array 
    mass [0] = 3.30E23; 
    mass [1] = 4.869E24; 
    mass [2] = 5.97E24; 
    mass [3] = 6.4219E23; 
    mass [4] = 1.900E27; 
    mass [5] = 5.68E26; 
    mass [6] = 8.683E25; 
    mass [7] = 1.0247E26; 

    // declare array for diameter 
    double[] diameter = new double[8]; 

    // initialize array 
    diameter [0] = 4880; 
    diameter [1] = 12103.6; 
    diameter [2] = 12756; 
    diameter [3] = 6794; 
    diameter [4] = 142984; 
    diameter [5] = 120536; 
    diameter [6] = 51118; 
    diameter [7] = 49532; 

    // // convert to radius 

    // declare radius variable 
    double radius; 

    // for each loop for displaying 
    for(double calc : diameter){ 

     // calculation for converting to radius 
     radius = calc/2; 
    } 

    // // calculate surface gravity 

    // declare and initialize universal gravity constant; 
    double G = 6.67384 * Math.pow(10, -11); 

    // call surface gravity method 
    surfaceGravity(G, mass, radius); 
} 
} 

Answer 1

您應該逐個計算double數組中的元素。

變化

// calculate surface gravity static method 
public static double surfaceGravity(double G, double[] M, double[] r){ 

    // equation for surface gravity 
    double[] g = (G * M)/Math.pow(r, 2); 

    // return statement 
    return g; 
} 

要

// calculate surface gravity static method 
public static double[] surfaceGravity(double G, double[] M, double[] r){ 

    // equation for surface gravity 
    double[] g = new double[M.length]; 

    for(int i=0;i<g.length;i++) 
    { 
     g[i] = (G * M[i])/Math.pow(r[i], 2); 
    } 

    // return statement 
    return g; 
} 

Answer 2

是的，你不能混合標量和數組。您需要重寫此方法：

public static double[] surfaceGravity(double G, double[] M, double[] r){ 

    double[] g = new double[M.length]; 
    // equation for surface gravity 
    for (int i=0; i < g.length; i++) { 
     g[i] = (G * M[i])/Math.pow(r[i], 2); 
    } 

    // return statement 
    return g; 
} 

Answer 3

完成其他的答案，你應該建立半徑的數組（因爲surfaceGravity需要double[]作爲其第三個參數）：

double[] radius = new double[diameter.length]; 

// for each loop for displaying 
for(int i = 0; i < diameter.length; i++) { 

    // calculation for converting to radius 
    radius[i] = calc/2; 
}