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  • Java 方法的重载

    class overLoad
    /**
    方法重载 :在同一个类中,可以有方法名重复,参数不同的 方法
    需求:1.在同一个类中,分别定义两个整数之和,两个小数之和。
    */
    {
    static int getSum(int i,int j){
    return i + j;
    }
    static double getSum(double a,double b){
    return a + b;
    }

    public static void main(String[] args) 
    {
    	int sum = overLoad.getSum(3,5);
    	System.out.println(sum);
    	double sum2 = overLoad.getSum(2.2,3.3);
    	System.out.println(sum2);
    }
    

    }

    +=================================================

    class Array01

    {
    /**
    打印数组中的元素
    */
    static void printArray(String[] arr)
    {
    if (arr == null)
    {
    System.out.println("null");
    return;//结束方法
    }
    String result = "[";
    for (int index = 0;index <arr.length ;index++ )
    {

    		result = result + arr[index];
    		if (index != arr.length-1)
    		{
    			result = result+",";
    		}
    	}
    	result = result+"]";
    	System.out.println(result);
    }
    
    //数组逆序排序
    static String[] reverse(String[] oldArr)
    {
    	//创建一个新的数组,存储颠倒后的元素
    	String[] newArray = new String[oldArr.length];
    	for (int index = oldArr.length-1;index>=0 ;index-- )
    	{
    		newArray[oldArr.length - 1 - index]  =  oldArr[index];
    	}
    	return newArray;
    	
    }
    /**
    查询key元素在arr数组中第一次出现的位置 
    参数:
    	arr:从哪一个数组中去做查询
    	key:当前查询的元素 
    返回:如果key存在于arr数组中,则返回第一次出现的索引,不存在则返回负一
    
    */ 
    
    static int fristIndex(int[] arr,int key)	
    {
    	for (int index = 0;index<arr.length ;index++ )
    	{
    		if (arr[index] == key)
    		{
    			return index;
    		}
    	}
    	return -1;
    }
    static int lastIndex(int[] arr,int key)
    {
    	for (int index = arr.length-1;index>=0 ;index-- )
    	{
    		if (arr[index] == key)
    		{
    			return index;
    		}
    	}
    	return -1;
    
    }
    
    public static void main(String[] args) 
    {
    	String[] arr = new String[]{"A","B","C","D","E"}; 
    	printArray(arr);
    	String[] newArr = Array01.reverse(arr);
    	printArray(newArr);
    
    	int[] num= new int[]{20,30,10,40,50,10};
    	
    	System.out.println(fristIndex(num,10));
    	System.out.println(lastIndex(num,10));
    
    }
    

    }

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  • 原文地址:https://www.cnblogs.com/thttt/p/11638462.html
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