Java計算平方與化為二進位

import javax.swing.*;
class compute
{
    long square(long x)
    {
        return x*x;
    }
    boolean[] binary(long x)
    {
        int bitN=(int)Math.ceil(Math.log(x+1)/Math.log(2));
        boolean [] b=new boolean[bitN];
        int i=bitN-1;
        do
        {
            b[i--]=((x&1)==1)?true:false;
            x=x>>1;
        } while (x!=0);
        for (i=0;i<bitN; i++)
            System.out.print(b[i]?1:0);
        System.out.println();
        return b;
    }
}
public class power
{
    public static void main(String[] argv) throws Exception
    {
        compute math=new compute();
        long x=new Long(JOptionPane.
        showInputDialog("x=")).longValue();
        boolean[] b=math.binary(x);
        long y=math.square(x);
        JOptionPane.showMessageDialog(null, x+"*"+x+"="+Long.toString(y));
    }
}

Java檔案讀寫

import java.io.*;
import java.util.*;
class student
{
    String name;
    int number;
}
public class readWriteFile
{
     public  static void main(String [] args) throws IOException
    {
        student[] X=new student[26];
   
        FileReader fr=new FileReader("student.txt");
        BufferedReader bfr=new BufferedReader(fr);

        String tmp;
        for (int i=0;i<26;i++)
        {
            X[i]=new student();
            tmp=bfr.readLine();
            X[i].name=tmp;
            X[i].number=(int)(100*Math.random());
        }
        fr.close();

        FileWriter fw=new FileWriter("List.txt");
        BufferedWriter bfw=new BufferedWriter(fw);
       
        for (int k=0;k<26;k++)
        {
            System.out.print(k+":");
            System.out.println(X[k].name+"\t"+X[k].number);
            bfw.write(k+":"+X[k].name+"\t"+X[k].number);
            bfw.newLine();
        }
        bfw.flush();
        fw.close();
    }
}
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林韋凱
鄭宇志
林挺生
林美君
彭聖媚
劉修駿
宋宏杰
吳俊昌
何啟維
湯志平
李逸翔
馬鴻岳
彭宇霆
黃羿綺
林香毓
陳秋茹

Java亂數排序

相關講義

import java.security.SecureRandom;
import java.util.Arrays;

public class bubbleSort
{
    static void bubbleSort(int [] data)
    {
        int temp;
        for (int i=data.length-1; i>0; i--)
            for (int j=0;j<i;j++)
                if (data[j]>data[j+1])
                {
                    temp=data[j];
                    data[j]=data[j+1];
                    data[j+1]=temp;
                }
       
    }
   
    public static void main(String [] argv)
    {
        SecureRandom rnd=new SecureRandom();
        int [] data=new int[26];
        int a,b;
        do
        {
            a=rnd.nextInt()%101;
            if (a<0) a+=101;
        } while (a==0);
        b=rnd.nextInt()%101+101;
        for (int i=0; i<26;i++)
        {
            data[i]=(a*i+b)%101;
            System.out.print("data["+i+"]="+data[i]+"\t");
        }
        System.out.println("\nBefore Sorting!");       
    //  bubbleSort(data);
        Arrays.sort(data); //quick sort
        for (int i=0;i<26;i++)
            System.out.print("data["+i+"]="+data[i]+"\t");
        System.out.println("\nAfter Sorting!");
    }
}