java实验一二三代码是啥呢？

本人大一学生，希望大佬能帮帮孩子谢谢了

package com.csdn;

import java.util.Arrays;
import java.util.HashSet;
import java.util.Set;

/**
 * 
 * @作者:Roc-xb
 * @联系QQ:327844761
 * @微信公众号：ewbang
 *
 */
public class Test01 {

	public static void t1() {
		int[] arr = { 20, 30, 40, 50, 60, 70, 80, 90 };
		int sum = 0;
		for (int i = 0; i < arr.length; i++) {
			sum += arr[i];
		}
		System.out.println("sum=" + sum);
	}

	public static void t2() {
		int[] arr = new int[100];
		for (int i = 0; i < arr.length; i++) {
			arr[i] = (int) (Math.random() * 100);
		}
		System.out.println("排序前的数组:" + Arrays.toString(arr));
		// 使用冒泡排序
		for (int i = 0; i < arr.length; i++) {
			for (int j = 0; j < arr.length - i - 1; j++) {
				if (arr[j + 1] < arr[j]) {
					int temp = arr[j + 1];
					arr[j + 1] = arr[j];
					arr[j] = temp;
				}
			}
		}

		System.out.println("排序后的数组:" + Arrays.toString(arr));
	}

	public static void t3() {
		String s = "a,b,c,d,e,f,g,h,b,b,b,c,x,x,y,x,b";
		// 先将字符串分割为数组
		String[] arr = s.split(",");
		System.out.println("分割后的数组：" + Arrays.toString(arr));
		// 数组去重
		Set<String> set = new HashSet<>();
		for (int i = 0; i < arr.length; i++) {
			set.add(arr[i]);
		}
		for (String o : set) {
			System.out.println(o);
		}

	}

	public static void main(String[] args) {
		t1();
		t2();
		t3();
	}
}

若有帮助，望采纳支持，谢谢！ 

public static void main(String[] args) {
    //一
    int[] arr0 = { 20, 30, 40, 50, 60, 70, 80, 90 };
    int sum = 0;
    for ( int i = 0; i < arr0.length; i++ ) {
        sum += arr0[i];
    }
    System.out.println( sum );

    //二
    int[] arr1 = new int[100];
    for ( int i = 0; i < arr1.length; i++ ) {
        arr1[i] = (int) (Math.random() * 100);
    }
    System.out.println( "数组长度:" + arr1.length );
    System.out.println( "排序前：" + Arrays.toString(arr1) );
    for ( int i = 0; i < arr1.length - 1; i++ ) {
        for ( int j = 0; j < arr1.length - i - 1; j++ ) {
            if ( arr1[j + 1] < arr1[j] ) {
                arr1[j]= arr1[j] ^ arr1[j + 1];
                arr1[j + 1] = arr1[j] ^ arr1[j + 1];
                arr1[j]= arr1[j] ^ arr1[j + 1];
            }
        }
    }
    System.out.println( "排序后：" + Arrays.toString(arr1) );

    //三
    String haha = "a,b,c,d,e,f,g,h,b,b,b,c,x,x,y,x,b";
    String[] hahas = haha.split(",");
    Set<String> set = new HashSet<>();
    for ( int i = 0; i < hahas.length; i++ ) {
        set.add( hahas[i] );
    }
    for ( String hehe : set ) {
        System.out.println(hehe);
    }
}

跟着你复习一下基础知识