求能实现加减乘除的java程序(输入1,2,3,4,分别对应实现加,减,乘,除...答:package swingTest;import java.util.InputMismatchException;import java.util.Scanner;public class numberinput {public static double jia(double n1,double n2){ //加return n1+n2;}public static double jian(double n1,double n2){ //减return n1-n2;}public static double chen(double n1,...