java——数组操作

 

排序、二分查找、复制数组、填充

package follow_pack;

import java.util.Arrays;
import java.text.DecimalFormat;

public class exp {
    public static void main(String[] args) {
        int array[] = {37,42,13,29,-9,6,33};
        for(int num : array) {
            System.out.print(num+" ");
        }
        System.out.println("");
        // 排序
        Arrays.sort(array);
        for(int num : array) {
            System.out.print(num+" ");
        }
        System.out.println(" ");
        // 二分查找
        System.out.println("查找33的结果如下："+Arrays.binarySearch(array, 33));
        int arrayB[] = new int[array.length];
        // 复制数组 copyOf,3代表要复制的元素个数
        arrayB = Arrays.copyOf(array, 3);
        for(int num: arrayB) {
            System.out.print(num+" ");
        }
        System.out.println(" ");
        // 复制数组 copyOfRange
        int arrayC[] = new int[array.length];
        arrayC = Arrays.copyOfRange(array, 4, 20);
        for(int num: arrayC) {
            System.out.print(num+" ");
        }
        System.out.println(" ");
        // 填充
        Arrays.fill(arrayC, 20);
        for(int num: arrayC) {
            System.out.print(num+" ");
        }
        System.out.println(" ");
        int arrayD[] = new int[10];
        Arrays.fill(arrayD, 1 ,3 , 12);
        for(int num: arrayD) {
            System.out.print(num+" ");
        }
        System.out.println(" ");
        // 比较数组
        System.out.println("arrayB == arratC?:"+Arrays.equals(arrayB, arrayC));
    }
}

 一维数组输出杨辉三角形：

public class exp {
    public static void main(String[] args) {
        int n=10;
        int[] table = new int[n+1];
        table[0] = 1;
        for(int i=1;i<=n;i++) {
            for(int j=0;j<i;j++) {
                System.out.print(" "+table[j]);
            }
            System.out.println();
            for(int j=i; j>0; j--)
                table[j] = table[j-1]+table[j];
        }
    }
}