Question

嗨我想知道是否有可能获得数组元素的长度？我检查了java文档，我看到的唯一可检索的长度是数组本身的长度。我的任务是使用元素的长度随机化我的砖块的颜色。如果有人可以指出获得元素长度的正确方向，那将非常感激。这是我的代码：

import javax.swing.JFrame;
import java.awt.Color;
import java.awt.Graphics;
import java.util.Random;

@SuppressWarnings("serial")
public class legos2v2 extends JFrame {
private int startX;
private int startY;
private int legoWidth;
private int legoHeight;
private int baseLength;
private int arcWidth;
private int arcHeight;
private Color[] colors;

// Constructor
public legos2v2() {
    super("Jimmy's LEGOs");
    startX = 20;
    startY = 300;
    legoWidth = 50;
    legoHeight = 20;
    baseLength = 10;
    arcWidth = 2;
    arcHeight = 2;


    // Declare and Array of Colors
    Color[] colors = {Color.red, Color.blue, Color.yellow, Color.green,
            Color.pink, Color.black, Color.magenta, Color.orange,
            Color.cyan};


    // Get length of color
    System.out.println("Array Length = " + colors.length + "\n");

}
// The drawings in the graphics context
public void paintComponent(Graphics g) {


    // Call the paint method of the JFrame
    super.paint(g);

    int currentX = startX;
    int currentY = startY;

    Random random = new Random();


    // row = 0 is the bottom row
    for (int row = 1; row <= baseLength; row++) {
        currentX = startX;

        for (int col = 0; col <= baseLength - row; col++) {

            g.fillRoundRect(currentX, currentY, legoWidth, legoHeight, arcWidth, arcHeight);


            // Generate random integer from 0 to 8
            int randomIndex = random.nextInt(colors.length);


            g.setColor(this.colors[randomIndex]);
            //Error here   this.colors = colors[randomIndex];



            // Print random integers to screen
            System.out.println(randomIndex);

            currentX = currentX + legoWidth;
        }
        currentY -= legoHeight;
        startX += legoWidth / 2;
    }
}
// The main method
public static void main(String[] args) {
    legos2v2 app = new legos2v2();
    // Set the size and the visibility
    app.setSize(550, 325);
    app.setVisible(true);
    // Exit on close is clicked
    app.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
}
}

Answer 1

老师要求你做的是我在评论中所说的：

初始化颜色数组：
```
Color[] colors = ...;
```
在0（包含）和数组长度之间生成一个随机int（不包括：
```
int randomIndex = random.nextInt(colors.length);
```
返回一个整数，它是颜色数组的有效索引。
选择随机索引处的颜色：
```
 Color color = colors[randomIndex];
```

这避免了丑陋的if块链产生随机颜色的需要。

编辑：

将Color[] colors =替换为this.colors =以初始化实例变量，而不是重新定义具有相同名称的本地变量
正如您在其他评论中被告知的那样，在第一个for循环之前移动Random random = new Random();
正如您在其他评论中被告知的那样，覆盖paintComponent()而不是覆盖paint()。

返回数组元素的长度

1 个答案: