第一题：import java.lang.Integer;import java.util.Arrays;class ArrDemo{    public static void main(String[] args){        int[] arr = new int[]{1,20,60,90,4};        //int[] arr = new int[5];//问题2、这个值并没有在错误判断里面，怎么判断？        System.out.println(Arrays.toString(arr));        int maxv = getMax(arr);        System.out.println(maxv);    }    public static int getMax(int[] arr){        int length = arr.length;        if(arr == null){//问题1、数组要怎么定义arr才等于null？            System.out.println("数组定义错误！null值！");            System.exit(0);        }else if(length == 0){            System.out.println("数组定义错误！长度等于0！");            System.exit(0);        }        int minv = Integer.MIN_VALUE;                for(int i=0;i
     
       minv){                minv = arr[i];            }        }        return minv;    }}第二题：    public static void main(String[] args){        int[] arr = new int[]{1,20,60,90,4,10,20};        System.out.println(Arrays.toString(arr));        int position = getPos(arr,4);        System.out.println(position);    }    public static int getPos(int[] arr,int v){        int num = 0;        int position = 0;        int length = arr.length;        if(arr == null){            System.out.println("数组定义错误！null值！");            System.exit(0);        }else if(length == 0){            System.out.println("数组定义错误！长度等于0！");            System.exit(0);        }                for(int i=0;i
      
       arr[j+1]){                    tmp = arr[j+1];                    arr[j+1] = arr[j];                    arr[j] = tmp;                }            }        }        return arr;    }第四题：public static void main(String[] args){        int[] arr = new int[]{1,2,3,.....,1021,1022,1023};  //log2^1024 = 10;        int binv = binSearch(arr,1023);        System.out.println(binv);}public static int binSearch(int[] arr,int v){        int length = arr.length;        int left = 0;        int right = length - 1;        int i = 0;        int r = 0;        int num = 0;        while(left <= right){            num ++;            i = (left + right)/2;            if(arr[i] == v){                r = i;                break;            }else if(arr[i] > v){                right = i - 1;            }else{//arr[i]
       
        = 1000){                break;            }        }        System.out.println(num);        return r;}第五题：首先是有序，一分为二的去查找，一次去掉一半数据，匹配次数成对数增长。第六题：public static void main(String[] args){        int[][] arr = {
    {1,2,3,4,5},{6,7,8,9,10},{11,12,13,14,15},{16,17,18,19,20},{21,22,23,24,25}};        for(int i=0;i