二维数组的遍历以及四种拷贝方式

例：数组的倒置以及合并

public class TestDemo1 {
    //反转数组
    public static void reverse(int[] array){
        for(int i =0;i<array.length/2;i++){
            int tmp = array[i];
            array[i] = array[array.length-1-i];
            array[array.length-1-i] = tmp;
        }
    }
    //合并数组
    public static void merge(int[] array1,int[] array2){
        int[] array3 = new int[array1.length+array2.length];
        for(int i = 0;i < array1.length;i++){
            array3[i] = array1[i];
        }

        for(int j = 0;j < array2.length;j++){
            array3[array1.length+j] = array2[j];
        }

        for(int k = 0;k < array3.length;k++){
            System.out.print(array3[k]+" ");
        }
        System.out.println();

    }
    public static void main(String[] args) {
        // TODO Auto-generated method stub
        int[] array = {
  
  12,34,21,22,4,6,81,2,1};
        int[] array2 = {
  
  5,8,10};
        reverse(array);
        merge(array,array2);
    }
}

运行结果如下：

二分查找例题

public class TestDemo1 {

    public static int Search(int[] array,int val){
        int low = 0;
        int high = array.length-1;
        while(low<=high){
            //int mid = (low+high)/2;
            //int mid = low+(high-low)/2;
            int mid = (low+high)>>>1;   //下标
            if(array[mid]>val){
                high = mid - 1;
            }else if(array[mid]<val){
                low = mid + 1;
            }else{
                return mid;
            }
        }
        return -(low+1);//源码中为-(low+1)   查找数据的插入点位置
    }
    public static void main(String[] args) {
        int[] array = {
  
  12,34,21,22,4,6,81,2,1};
        Arrays.sort(array);
        System.out.println(Arrays.toString(array));
        int index = Arrays.binarySearch(array,12);
        System.out.println(index);
        //binarySearch  二分查找
    }

}

运行结果如下：

二维数组的遍历

基本类型

public static void show1(int[][] array){
        for(int i = 0;i<array.length;i++){
            for(int j = 0;j<array[i].length;j++){
                System.out.println(array[i][j]+" ");
            }
            System.out.println();
        }
    }

引用类型

public static void show2(TestArray[][] Array)
    {
        for (int i = 0; i < Array.length; i++) {
            for (int