lettercounting.java

压缩包内是近180多个针对Java初学者编写的简单实例

import javax.swing.*;
public class LetterCounting {
	public static	final int LETTERNUMBER=26;
	public static void main(String args[]){
		//提示用户输入
		String s = JOptionPane.showInputDialog(null,"输入一个字符串："
				,"示例输入",JOptionPane.QUESTION_MESSAGE);
		
		//invoking the count letters method to count each lettr.
		int []numberUpper=countUpper(s);
		int []numberLower= countLower(s);
		
		//decare and initialize the output string.
		String output = "";
		
		//display the result.
		for(int i=0;i<numberUpper.length;i++){
			if(numberUpper[i]!=0) output+=(char)('A'+i)+" 出现在 "+ "次数\n";
		}
		for(int i=0;i<numberLower.length;i++){
			if(numberLower[i]!=0) output+=(char)('a'+i)+"  出现"+"次数\n";
		}
		
		JOptionPane.showMessageDialog(null,output,"示例输出",JOptionPane.INFORMATION_MESSAGE);
	}
	public static int[] countUpper(String s){
		int []count = new int[LETTERNUMBER];
		
		for(int i=0;i<s.length();i++){
			if(Character.isUpperCase(s.charAt(i)))
				count[(int)(s.charAt(i)-'A')]++;
		}
		return count;
	}
	public static int[] countLower(String s){
		int []count = new int[LETTERNUMBER];
		for(int i=0;i<s.length();i++){
			if(Character.isLowerCase(s.charAt(i)))
			count[(int)(s.charAt(i)-'a')]++;
		}
	return count;	
	}
}