Question

我不明白参数和参数之间的连接或区别。你能用这两种方法吗？你怎么回答论点？非常感谢任何帮助。

Answer 1

警告：很多人不区分“参数”和“参数”。他们应该，但他们不这样做 - 所以你很可能会看到许多页面使用不正确的术语。

当您声明方法或构造函数时，参数是您在声明中放置以接收要使用的值的位。例如：

import java.awt.*;
import java.awt.event.*;
import javax.swing.*;

public class SimpleGui implements ActionListener {

    private MyDrawPanel drawPanel;

    public static void main(String[] args) {
        Runnable r = new Runnable () {
            @Override
            public void run () {
                new SimpleGui ().go ();
            }
        };
        EventQueue.invokeLater ( r );
    }

    public void go() {
        drawPanel = new MyDrawPanel();

        JFrame frame = new JFrame();
        frame.setDefaultCloseOperation( JFrame.DISPOSE_ON_CLOSE );
        JButton button = new JButton( "Change colors" );
        button.addActionListener( this );

        frame.add( drawPanel, BorderLayout.CENTER );
        frame.add( button, BorderLayout.PAGE_END );
        frame.pack ();
        frame.setLocationByPlatform ( true );
        frame.setVisible(true);
    }

    public void actionPerformed(ActionEvent event) {
        drawPanel.setValues ();
    }
}

class MyDrawPanel extends JPanel {

    private int width = 300;
    private int height = 300;

    private int red;
    private int green;
    private int blue;

    private Color randomColor;

    /*
     * Make this one customary habbit,
     * of overriding this method, when
     * you extends a JPanel/JComponent,
     * to define it's Preferred Size.
     * Now in this case we want it to be 
     * as big as the Image itself.
     */
    @Override
    public Dimension getPreferredSize () {
        return new Dimension ( width, height );
    }

    public void setValues () {
        red = ( int ) ( Math.random() * 255 );
        green = ( int) ( Math.random() * 255 );
        blue = ( int ) ( Math.random() * 255 );

        randomColor = new Color( red, green, blue );

        repaint ();
    }

    /*
     * This is where the actual Painting
     * Code for the JPanel/JComponent goes.
     * Here the first line super.paintComponent(...),
     * means we want the JPanel to be drawn the usual 
     * Java way first (this usually depends on the opaque
     * property of the said JComponent, if it's true, then
     * it becomes the responsibility on the part of the
     * programmer to fill the content area with a fully
     * opaque color. If it is false, then the programmer
     * is free to leave it untouched. So in order to 
     * overcome the hassle assoicated with this contract,
     * super.paintComponent(g) is used, since it adheres
     * to the rules, and performs the same task, depending
     * upon whether the opaque property is true or false),
     * then later on we will add our image to it, by 
     * writing the other line, g.drawImage(...).
     */
    @Override
    protected void paintComponent(Graphics g) {
        super.paintComponent ( g );

        g.setColor(randomColor);
        g.fillOval(70, 70, 100, 100);
    }
}

此处public void foo(int x, int y)和x是参数。在方法中，它们就像局部变量一样。

当您调用方法或构造函数时，参数是您传入的值。这些参数用作参数的初始值。例如：

此处5和3是参数 - 因此参数foo(5, 3);将以值5开头，参数x将以值3开头。当然，您可以使用参数（或任何其他变量）也作为参数。例如：

此处public void foo(int x, int y) { System.out.println(y); }是y方法中的参数，但其值被用作foo方法的参数。

你能用它作为方法吗？

不，他们是一个完全不同的概念。

你如何回归论点？

同样，这并没有多大意义。您可以在return语句中使用参数的值：

println

如何在java中使用参数和参数？

1 个答案: