关于方法的三个练习

package com.jsu.www;
import java.lang.reflect.Array;
public class New04 {
    public static void main(String[] args) {
        int arr[]={11,22,33,44,55};//明确要打印的对象
        printfArr(arr);//定义一个方法来打印
    }
    public static void printfArr(int arr[]) {
        System.out.print("[");
        for (int i = 0; i < arr.length; i++) {
            if (i== arr.length-1)
                System.out.print(arr[i]);
            else
                System.out.print(arr[i]+",");
        }
        System.out.print("]");
    }
}

package com.jsu.www;
import java.util.Scanner;
public class New05 {
    public static void main(String[] args) {
        Scanner scanner=new Scanner(System.in);
        int arr[]={1,2,3,4,5};
        int num=scanner.nextInt();//将要判断的数输入
        System.out.println(contain(arr,num));//注意不要写arr[]
    }
    public static boolean contain(int arr[],int num ) {
        for (int i = 0; i < arr.length; i++) {//遍历数组每一个元素
            if(num==arr[i])
                return true;
        }
        return false;
    }
}

package com.jsu.www;

public class New06 {
    public static void main(String[] args) {
        int arr[]={1,2,3,4,5,6};
        int copyArr[]=copyOfRange(arr,0,3);
        for (int i = 0; i < copyArr.length; i++) {
            System.out.print(copyArr[i]+" ");
        }
    }
    public static int[] copyOfRange(int arr[],int from,int to ) {
        int newArr[]=new int[to-from];//动态分配
        int index=0;
        for (int i = from; i < to; i++) {
            newArr[index]=arr[i];
            index++;
        }
        return newArr;
    }
}