import java.util.Scanner;
public class addd {
	  public static void main(String[] args) {
		  Scanner sc = new Scanner(System.in);
//定义数据类型
		  double L, IL = 0;
		  System.out.print("请输入尺寸:");
//数值的录入
		  L = sc.nextDouble();
		  System.out.print("请输入单位:");
//字符串的录入
		  String dw = sc.next();
//判断关键字符是“cm”
		    if (dw.equals("cm") ){
			    IL = L / 2.54;
			    System.out.printf("%.1f厘米=%.1f英寸",L , IL);
		  }
//判断关键字符是“inch”
		    else if(dw.equals("inch") ){
			    IL = L * 2.54;
			    System.out.printf("%.1f英寸=%.1f厘米",L , IL);
		  }
		  sc.close();
	}
}
原文:http://www.cnblogs.com/JamseWilson/p/4025378.html