java练习答案

import java.util.Scanner; public class Check {

public static void main(String[] args) { Scanner sc = new Scanner(System.in);

System.out.println(\"请输入一个不超过10,000,000的正整数：\"); String temp = sc.next();

StringBuffer buffer1 = new StringBuffer(temp);

StringBuffer buffer2 = new StringBuffer(temp).reverse(); buffer1 = new StringBuffer(temp);

if (buffer1.toString().equals(buffer2.toString())) { System.out.println(buffer1 + \"是回文数。\"); } else {

System.out.println(buffer1 + \"不是回文数。\"); } } }

2.从键盘读入2个正整数m和n，若m≤n，则求出在[m,n]之间的所有素数；否则求出在[n,m]之间的所有素数。

import java.util.Scanner; public class TestPrime {

public static void main(String[] args) { Scanner sc = new Scanner(System.in); System.out.println(\"请输入2个正整数\"); System.out.print(\"第一个：\"); int m = sc.nextInt();

System.out.print(\"第二个：\"); int n = sc.nextInt(); if (m <= n) {

for(int i = m ;i<=n ; i++){ if(IsPrime(i)){

System.out.println(i+\" \"); } } }else{

for(int i = n; i <= m ; i++){ if(IsPrime(i)){

System.out.println(i+\" \"); } } } }

public static boolean IsPrime(int k) { if (k == 2) return true; else if (k % 2 == 0) return false; else {

for (int i = 2; i <= Math.sqrt(k); i++) if (k % i == 0) return false; return true; } }

}

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