简单的排序算法（冒泡、选择、插入）

package com.sw.demo.test;

public class Test {
	public static void main(String[] args) {
		
		int[] arr = {1,7,3,2,6,5,4,8,9};
		
		System.out.println("--------------- 排序前 ---------------");
		for (int i = 0; i < arr.length; i++) {
			System.out.print(arr[i]+"  ");
		}
		System.out.println();
		
		//insertSort(arr);
		//selectSort(arr);
		bubbleSort(arr);
		System.out.println("--------------- 排序后 ---------------");
		
		for (int i = 0; i < arr.length; i++) {
			System.out.print(arr[i]+"  ");
		}
	}
	
	/**
	 * 冒泡排序
	 * @param arr
	 * @return
	 */
	public static int[] bubbleSort(int[] arr){
		int tmp;
		for (int i = 0; i < arr.length-1; i++) {
			for (int j = 0; j < arr.length-1-i; j++) {
				if(arr[j] > arr[j+1]){
					tmp = arr[j];
					arr[j] = arr[j+1];
					arr[j+1] = tmp;
				}
			}
		}
		
		return arr;
	}
	
	/**
	 * 选择排序
	 * @param arr
	 * @return
	 */
	public static int [] selectSort(int[] arr){
		int tmp;
		for (int i = 0; i < arr.length; i++) {
			for (int j = i+1; j < arr.length; j++) {
				if(arr[i] > arr[j]){
					tmp = arr[i];
					arr[i] = arr[j];
					arr[j] = tmp;
				}
			}
		}
		
		return arr;
	}
	
	
	/**
	 * 插入排序法
	 * @param arr
	 * @return
	 */
	public static int[] insertSort(int [] arr){
		int tmp ;
		for (int i = 1; i < arr.length; i++) {
			for (int j = i; j >0; j--) {
				if(arr[j] < arr[j-1]){
					tmp = arr[j];
					arr[j] = arr[j-1];
					arr[j-1] = tmp;
				}else{
					break;
				}
			}
		}
		
		return arr;
	}
}