优化后的排序算法：

//TestNumberSort.java

public class TestNumberSort{
	public static void main(String args[]) {
		int a[] = new int[args.length];
		for(int i = 0; i < args.length; i++) {
			a[i] = Integer.parseInt(args[i]);
		}
		print(a);
		SelectionSort(a);
		print(a);
		/*
		int a[];
		a = new int[9];
		a[0] = Integer.parseInteger(args[0]);
		a[1] = Integer.parseInteger(args[1]);
		a[2] = Integer.parseInteger(args[2]);
		a[3] = Integer.parseInteger(args[3]);
		a[4] = Integer.parseInteger(args[4]);
		a[5] = Integer.parseInteger(args[5]);
		a[6] = Integer.parseInteger(args[6]);
		a[7] = Integer.parseInteger(args[7]);
		a[8] = Integer.parseInteger(args[8]);
		sort();
		for(int i = 0; i < a.length; i++) {
			System.out.print(a[i] + " ");
		}
		*/
	}
    
	/*
	private static void SelectionSort(int a[]) {
		for(int i = 0; i < a.length; i++) 
			for(int j=i+1; j<a.length; j++) {
				if(a[i] > a[j]) {
					int temp = a[i];
					a[i] = a[j];
					a[j] = temp;
				}
		}
	}
	*/

	private static void SelectionSort(int a[]) {
		int k,temp;
		for(int i = 0; i < a.length; i++) {
			k = i;
			for(int j = k; j<a.length; j++) {
				if(a[j] < a[k]) {
					k = j;
				}
			}
			if( k != i) {
				temp = a[i];
				a[i] = a[k];
				a[k] = temp;
			}
		}	
	}

    private static void print(int a[]) {
		for(int i = 0; i < a.length; i++) {
			System.out.print(a[i] + " ");
		}
		System.out.println();
	}
	/*
	public void sort() {
		int i = 0;
		int j;
		for(j = i + 1; j < a.length; i++, j++) {
				if(a[i] > a[j]) {
					int temp;
					temp = a[i];
					a[i] = a[j];
					a[j] = temp;
				}
		}
	}
	*/
}

阅读下面的程序，任意初始化days数组，然后对days数组排序，再用折半查找法查找特定的Date对象day

//Test.java

public class Test {
	public static void main(String args[]) {
		Date[] days = new Date[10];
		Date day = new Date(2004, 4, 6);
	}
}

class Date {
	int day,month,year;
	Date(int y, int m, int y) {
		this.year = y;
		this.month = m;
		this.day = d;
	}

	public int compare(Date date) {
		return year > date.year ? 1 
			: year < date.year ? -1 
			: month > date.month ? 1
			: month < date.month ? -1
			: day > date.day ? 1
			: day < date.day ? -1 : 0;
	}
}