【Java学习日记】#8 数组 #3 练习题

1.创建数组arr1和arr2将arr1中索引位置是0~3中的元素复制到数组arr2中并输出。

import java.util.Arrays;
public class HelloJava {
	public static void main(String[] args) {
		int arr1[] = new int[]{1,2,3,4,5};
		int arr2[] = Arrays.copyOfRange(arr1, 0, 3);
		for(int i : arr2) System.out.println(i);
	}
}

2.将数组中最小的数输出

import java.util.Arrays;
public class HelloJava {
	public static void main(String[] args) {
		int arr1[] = new int[]{7,2,9,4,3,8};
		Arrays.sort(arr1);
		System.out.println(arr1[0]);
	}
}

3.将数组arr中索引位置是2的元素替换为“bb”，输出数组替换前及替换后的所有元素。

import java.util.Arrays;
public class HelloJava {
	public static void main(String[] args) {
		String s[] = new String[] {"AB","UU","HAS","SAJ"};
		for(String x:s)System.out.print(x+" ");
		System.out.println();
		Arrays.fill(s, 1,2,"bb");
		for(String x:s)System.out.print(x+" ");
	}
}

4.显示二维数组行列互调后的结果

public class HelloJava {
	public static void main(String[] args) {
		int a[][] = new int[][] {{1,2,3},{4,5,6},{7,8,9}};
		for(int i=0;i<a.length;i++) {
			for(int j=0;j<a[i].length;j++) System.out.print(a[i][j]);
			System.out.println();
		}
		System.out.println();
		for(int i=0;i<a.length;i++) {
			for(int j=0;j<a[i].length;j++) System.out.print(a[j][i]);
			System.out.println();
		}
	}
}