Java面向对象程序设计答案第6章----Java常用类（三角形面积公式，vector,InputDialog）

第六章答案

1、用公式计算三角形面积

package com.xiujie.part_6;

import java.util.Scanner;
import java.lang.Math;
import java.text.DecimalFormat;
public class GetS {
	public static void main(String[] args) {
		Scanner scanner=new Scanner(System.in);
		System.out.println("请输入三角形两边边边长");
		int a=scanner.nextInt();
		int b=scanner.nextInt();
		System.out.println("请输入三角形的夹角度数");
		double c=scanner.nextDouble();
		double r=Math.toRadians(c);
		double s;
		s=a*b*Math.sin(r)/2;
		DecimalFormat decimalFormat=new DecimalFormat("0.00");
		String string=decimalFormat.format(s);
		System.out.println("三角形面积为"+string);
		scanner.close();
	}
}

2、Vector保存用户输入的若干字符串

package com.xiujie.part_6;

import java.util.Scanner;
import java.util.Vector;

public class PrintString {
	public static void main(String[] args) {
		Scanner scanner=new Scanner(System.in);
		System.out.println("请输入内容");
		Vector box=new Vector();
		String string=null;
		int i=0;
		while(true) {
			string=scanner.nextLine();
			if (string.contains("end")) {
				break;
			}
			i++;
			box.addElement(string);
			
		}
		System.out.println(box.toString());
		System.out.println("插入NICE后为");
		box.insertElementAt("NICE",i/2);
		System.out.println(box.toString());
		scanner.close();
	}
}

3、显示对话框实现英文单词的简单处理

package com.xiujie.part_6;
//该part之前没有学过，是雪儿现学现卖写的，有什么不足之处欢迎大家指出，可以私我哟！
import javax.swing.JOptionPane;

public class InputDialog {
	public static void main(String[] args) {
	//功能a
	String input=JOptionPane.showInputDialog("请输入一个英文单词");
	//进入功能b
	Object[] possibleObjects= {"转换为大写","转换为小写","反转显示"};
	Object selectObject=JOptionPane.showInputDialog(null, "请选择", "输入", 
			JOptionPane.INFORMATION_MESSAGE, null, possibleObjects, possibleObjects[0]);
	String string=(String) selectObject;
	String str=null;
	if (string.equals(possibleObjects[0])) {
		str=input.toUpperCase();
		JOptionPane.showMessageDialog(null,str,"操作结果",JOptionPane.INFORMATION_MESSAGE);
	}else if (string.equals(possibleObjects[1])) {
		str=input.toLowerCase();
		JOptionPane.showMessageDialog(null,str,"操作结果",JOptionPane.INFORMATION_MESSAGE);
	}else if (string.equals(possibleObjects[2])) {
		String str2=new StringBuffer(input).reverse().toString();
		JOptionPane.showMessageDialog(null, str2,"操作结果",JOptionPane.INFORMATION_MESSAGE);
	}
	
}
}

本文地址：https://blog.csdn.net/qq_36171670/article/details/112227815