Java基础编程题—1

1.编写一个圆类Circle,该类拥有：...，并打印输出

package test;

public class Circle {
	
	protected  double radius;
	
	public Circle(){
		radius = 0;
	}
	public Circle(double r){
		radius =  r ;
	}
	
	public  double getArea() {
		return radius*radius*Math.PI;
	}
	
	public double getPerimeter() {
		return 2*Math.PI*radius;
	}
	
	public void show() {
		System.out.println("圆的半径 ："+radius);
		System.out.println("圆的周长 ："+getPerimeter());
		System.out.println("圆的面积 ："+getArea());
	}
	
	
	public static void main (String args[]) {
		
		Cylinder c = new Cylinder(2,3.0);
		c.show();
		//c.showVolume();
	}
	
}

 

2.编写一个圆柱类Cylinder,它继承于上面的Circle类。还拥有：...

package test;

public class Cylinder extends Circle {
	private double hight;
	
	public Cylinder (double r, double h) {
		super(r);
		this.hight = h;
		
	}
	
	public  double getVolume() {
		return super.getArea()*hight;
	}

	void showVolume() {
		System.out.println("圆柱的体积："+getVolume());
	}
}

 

3.求1~100能被三整除的个数是多少？并求和。

package test;

import java.awt.List;
import java.util.ArrayList;

public class DivisibleSum {
	private static ArrayList arr = new ArrayList();
	private static  int num=0;
	
	public static  void divisible(int x) {
		
		for (int i = 1;i<101;i++) {
			if(i%x==0) {
				//a[num]=i;
				arr.add(i);
				num++;	
			}
		}
	}
	
	public static void main (String args[]) {
		
		divisible(3);
		System.out.println("被3整除的个数"+num);
		
		int sum =0;
		for(int i = 0; i

 

4.输入一个字符串，判断是否为回文？

package test;

import java.util.Scanner;

public class HuiwenTest {
	
	//输入字符串 reverse倒置，然后比较
	public static  void main (String agrs[]) {
		
		System.out.print("请输入一个字符串：");
		Scanner input = new Scanner(System.in);
		
		String str = input.next();
		StringBuffer buff = new StringBuffer(str);
		buff.reverse();
		String newstr = new String(buff);
		
		if(str.equals(newstr)) {
			System.out.println(str+" 此字符串是回文！");
		}else {
			System.out.println(str+" 字符串不是回文！");
		}
	}
}

 

5.冒泡排序（找出第二大的数）

package test;

public class BubbleSort {
	
	public static int[] bubbleSort(int arr[]) {
		
		for(int i = 0;iarr[j+1]) {
					temp =arr[j];
					arr[j] = arr[j+1];
					arr[j+1] = temp;
				}
			}
		}
		return arr;
	}
	
	
	public static void main(String args[]) {
		int[] a = {3,26,1,4,7,29,9,7,63};
		a = bubbleSort(a);
		for(int i = 0; i

 

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