2018.12.1 Java [1]

1. 使用for循环打印乘法口诀表

1.public class multiplicationTables
{public static void main(String[] args)
{
for(int i=1;i<=9;i++)
{for(int j=1;j<=i;j++)
{int k=i*j;
System.out.print(i+"*"+j+"="+k+"\t");}
System.out.print("\n");
}
}
}

2. 递归实现20!

public class Factior
{public static void main(String[] args)
{long mul=1;
for(int i=1;i<=20;i++)
{mul=mul*i;}
System.out.println(mul);}
}

3. 完成ArrayUtils.java
   //1.计算数组中最大值
   public static int arrayMaxElement(int[] data){
   //TODO
   return -1;
   }

   //2.计算数组中最小值
   public static int arrayMinElement(int[] data){
   //TODO
   return -1;
   }

   //3.计算数组值之和
   public static int arrayElementSum(int[] data){
   //TODO
   return -1;
   }

   //4.数组拼接
   // A {1,3,5,7,9} B {2,4,6,8,10} -> {1,3,5,7,9,2,4,6,8,10}
   public static int[] arrayJoin(int[] a, int[] b){
   //TODO
   return null;
   }

   //5.数组截取
   //[start, end)
   // A {1,3,5,7,9} ->(A,1,3) > {3,5}
   public static int[] arraySub(int[] data, int start , int end){
   //TODO
   return null;
   }

   //6.数组打印
   public static void printArray(int[] data){
   //TODO
   }

   //7.数组反转
   // 比如：[1,2,3,4] => [4,3,2,1]
   public static void printReversal(int[] data){
   //TODO
   }

   public static void main(String[] args){
   //TODO 测试
   }
   }

public class ArrayUtils

{public static void main(String[] args){
int[]data=new int[]{1,1111,2,3,22,444,5555,99};
int[]a=new int[]{1,2,3,4,5,6};
int[]b=new int[]{2,3,4,5,6,7};
arrayMaxElement(data);
arrayMinElement(data);
arrayElementSum(data);
arrayJoin(a,b);
printArray(data);
printReversal(data);
 }

public static int arrayMaxElement(int[] data)
  {int Max=data[0];
  for(int i=0;i<data.length;i++)
  {if(data[i]>=Max) Max=data[i];}
  System.out.println(Max);
return -1;}

public static int arrayMinElement(int[] data)
{
int Min=data[0];
  for(int i=0;i<data.length;i++)
  {if(data[i]<=Min) Min=data[i];}
  System.out.println(Min);
return -1;}

public static int arrayElementSum(int[] data)
{{int sum=0;
for(int i=0;i<data.length;i++)
{sum=sum+data[i];}
System.out.println(sum);
return -1;}
}

 public static int[] arrayJoin(int[] a, int[] b)
 {int[]x=new int [a.length+b.length];
 int i=0;
 for(i=0;i<a.length;i++)
{x[i]=a[i];}
int t=i-a.length;
for(;i<x.length;i++,t++)
{x[i]=b[t];}
for(i=0;i<x.length;i++)
System.out.println(x[i]);
return null;}

public static void printArray(int[] data){
  for(int i=0;i<data.length;i++)
System.out.println(data[i]);
    }

 public static void printReversal(int[] data){
   int temp=0;
for(int i=0;i<data.length/2;i++)
{temp=data[i];
data[i]=data[data.length-1-i];
data[data.length-1-i]=temp;}
for(int i=0;i<data.length;i++)
System.out.println(data[i]);
 }
}