所以我试图在不同的类中调用我的方法。
这是一个简单的任务，我在这里看了很多教程和其他帖子，但由于某种原因我无法让它工作。
这是第一堂课
public class ArrayProcessor {
public void print3IntArray(int[] array) {
for (int i = 0; i < 3; i++) {
System.out.println("Entry " + i + " is " + array[i]);
}
}
}
我第一次尝试
import java.util.Random;
public class ArrayProgram {
public static void main(String[] args) {
Random rand = new Random();
int[] anArray = new int[3];
for(int i = 0; i < 3; i++) {
int random = rand.nextInt(11);
anArray[i] = random;
}
}
ArrayProcessor.print3IntArray(anArray);
}
但是在看了这个网站上的一些帖子之后我试过了
import java.util.Random;
public class ArrayProgram {
public static void main(String[] args) {
ArrayProcessor ap = new ArrayProcessor();
Random rand = new Random();
int[] anArray = new int[3];
for(int i = 0; i < 3; i++) {
int random = rand.nextInt(11);
anArray[i] = random;
}
}
ap.print3IntArray(anArray);
}
这两个代码都给我以下错误：
ArrayProgram.java:21: error: <identifier> expected
ap.print3IntArray(anArray);
^
ArrayProgram.java:21: error: <identifier> expected
ap.print3IntArray(anArray);
^
2 errors
答案 0 :(得分：1)
你在说这个
ap.print3IntArray(anArray);
在main方法的结束大括号之后，因此您的代码实际上不驻留在任何方法或容器代码块中，这是编译器无法接受的。变化
} // closing curly brace of main()
ap.print3IntArray(anArray);
到
ap.print3IntArray(anArray);
} // closing curly brace of main()
答案 1 :(得分：0)
你不能打电话
import java.awt.BorderLayout;
import java.awt.Color;
import java.awt.Dimension;
import java.awt.EventQueue;
import java.awt.Graphics;
import java.awt.Graphics2D;
import java.awt.Rectangle;
import java.awt.geom.Rectangle2D;
import java.util.Map;
import java.util.TreeMap;
import javax.swing.JFrame;
import javax.swing.JPanel;
import javax.swing.JScrollPane;
import javax.swing.Scrollable;
public class Main {
public static void main(String[] args) {
EventQueue.invokeLater(new Runnable() {
@Override
public void run() {
new Main();
}
});
}
public Main() {
// For this example, I just randomised some data, you would
// Need to load it yourself...
int width = 256;
int height = 256;
int[][] data = new int[width][height];
for (int c = 0; c < height; c++) {
for (int r = 0; r < width; r++) {
data[c][r] = (int) (256 * Math.random());
}
}
Map<Integer, Integer> mapHistory = new TreeMap<Integer, Integer>();
for (int c = 0; c < data.length; c++) {
for (int r = 0; r < data[c].length; r++) {
int value = data[c][r];
int amount = 0;
if (mapHistory.containsKey(value)) {
amount = mapHistory.get(value);
amount++;
} else {
amount = 1;
}
mapHistory.put(value, amount);
}
}
JFrame frame = new JFrame("Test");
frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
frame.setLayout(new BorderLayout());
frame.add(new JScrollPane(new Graph(mapHistory)));
frame.pack();
frame.setLocationRelativeTo(null);
frame.setVisible(true);
}
protected class Graph extends JPanel implements Scrollable {
protected static final int MIN_BAR_WIDTH = 4;
private Map<Integer, Integer> mapHistory;
public Graph(Map<Integer, Integer> mapHistory) {
this.mapHistory = mapHistory;
}
@Override
public Dimension getPreferredSize() {
int width = (mapHistory.size() * MIN_BAR_WIDTH) + 11;
return new Dimension(width, 256);
}
@Override
public Dimension getMinimumSize() {
int width = (mapHistory.size() * MIN_BAR_WIDTH) + 11;
return new Dimension(width, 128);
}
@Override
protected void paintComponent(Graphics g) {
super.paintComponent(g);
if (mapHistory != null) {
int xOffset = 5;
int yOffset = 5;
int width = getWidth() - 1 - (xOffset * 2);
int height = getHeight() - 1 - (yOffset * 2);
Graphics2D g2d = (Graphics2D) g.create();
g2d.setColor(Color.DARK_GRAY);
g2d.drawRect(xOffset, yOffset, width, height);
int barWidth = Math.max(MIN_BAR_WIDTH,
(int) Math.floor((float) width
/ (float) mapHistory.size()));
int maxValue = 0;
for (Integer key : mapHistory.keySet()) {
int value = mapHistory.get(key);
maxValue = Math.max(maxValue, value);
}
int xPos = xOffset;
for (Integer key : mapHistory.keySet()) {
int value = mapHistory.get(key);
int barHeight = Math.round(((float) value
/ (float) maxValue) * height);
g2d.setColor(new Color(key, key, key));
int yPos = height + yOffset - barHeight;
Rectangle2D bar = new Rectangle2D.Float(
xPos, yPos, barWidth, barHeight);
g2d.fill(bar);
g2d.setColor(Color.DARK_GRAY);
g2d.draw(bar);
xPos += barWidth;
}
g2d.dispose();
}
}
@Override
public Dimension getPreferredScrollableViewportSize() {
return new Dimension(512, 256);
}
@Override
public int getScrollableUnitIncrement(Rectangle visibleRect, int orientation, int direction) {
return 128;
}
@Override
public int getScrollableBlockIncrement(Rectangle visibleRect, int orientation, int direction) {
return 128;
}
@Override
public boolean getScrollableTracksViewportWidth() {
return getPreferredSize().width
<= getParent().getSize().width;
}
@Override
public boolean getScrollableTracksViewportHeight() {
return getPreferredSize().height
<= getParent().getSize().height;
}
}
}
在方法外部（在本例中为main方法）但是如果你想在main方法中调用它，那么在ArrayProcessor类中使函数print3IntArray为静态。
ArrayProcessor.print3IntArray(anArray);