Question

import java.awt.Color;
import java.awt.Graphics;
import java.awt.Color;
import javax.swing.JPanel;
import java.util.Scanner;

public class BarGraph extends JPanel
{
  private int n1, n2, n3, n4, n5;
    BarGraph(int num1, int num2, int num3, int num4, int num5)
    {
        int n1 = num1;
        int n2 = num2;
        int n3 = num3;
        int n4 = num4;
        int n5 = num5;
    }

    public void paintComponent( Graphics g )
    {
        super.paintComponent(g);
        g.drawRect(0, 100, 100, 10);
        g.drawRect(0, 0, n1 * 10, 10);
        g.drawRect(0,20, n2 * 10, 10);
        g.drawRect(0,40, n3 * 10, 10);
        g.drawRect(0,60, n4 * 10, 10);
        g.drawRect(0,80, n5 * 10, 10);
     System.out.print(n1);
    }
}

BarGraphTest

package BarGraph;

import javax.swing.JFrame;
import javax.swing.JOptionPane;
import java.util.Scanner;
/*
 * To change this license header, choose License Headers in Project Properties.
 * To change this template file, choose Tools | Templates
 * and open the template in the editor.
 */

/**
 *
 * @author AJ
 */
public class BarGraphTest
{
    public static void main( String[] args)
    {

                System.out.print("Enter 5 integers seperated by spaces:");
                Scanner input = new Scanner(System.in);
                int n1 = input.nextInt();
                int n2 = input.nextInt();
                int n3 = input.nextInt();
                int n4 = input.nextInt();
                int n5 = input.nextInt();

        BarGraph panel = new BarGraph(n1, n2, n3, n4, n5);
        JFrame application = new JFrame();
        application.setDefaultCloseOperation( JFrame.EXIT_ON_CLOSE );
        application.add( panel );
        application.setSize( 300, 300);
        application.setVisible( true );
    }
}

基本上尝试获得5个整数并绘制5个相应缩放的矩形。我的变量虽然是空的。我错过了什么吗？我System.out.printed了变量n1，但它没有任何内容。

Answer 1

在BarGraph的构造函数中，您已声明了局部变量并忽略了类变量，因此不会分配类变量。局部变量优先于类变量。删除int以删除声明，类变量将得到正确解析。

更改

BarGraph(int num1, int num2, int num3, int num4, int num5)
{
    int n1 = num1;
    int n2 = num2;
    int n3 = num3;
    int n4 = num4;
    int n5 = num5;
}

到

BarGraph(int num1, int num2, int num3, int num4, int num5)
{
    n1 = num1;
    n2 = num2;
    n3 = num3;
    n4 = num4;
    n5 = num5;
}

类不读取构造函数属性

1 个答案: