直接选择排序Java实现

About this application:

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This application implements Straight Selection Sort algorithm which is described like this:

If there are N numbers find the minimum and exchange it with the first number then N numbers remained Continue to find the minimum number in the remained N numbers and exchange it with the second number Repeat this until all the numbers are in order

Note: This is SWT application so you need eclipse swt win win x _ v b jar eclipse jface_ I jar mands_ I jar This is for Eclipse

Source Code:

package selection sort;

import java util ArrayList;

import eclipse swt SWT;

import eclipse swt events KeyAdapter;

import eclipse swt events KeyEvent;

import eclipse swt events ModifyEvent;

import eclipse swt events ModifyListener;

import eclipse swt events SelectionAdapter;

import eclipse swt events SelectionEvent;

import eclipse swt layout FormAttachment;

import eclipse swt layout FormData;

import eclipse swt layout FormLayout;

import eclipse swt widgets Button;

import eclipse swt widgets Display;

import eclipse swt widgets Group;

import eclipse swt widgets Label;

import eclipse swt widgets Shell;

import eclipse swt widgets Text;

/**

* This application implements Straight Selection Sort algorithm which means

* get the minimum number from the numbers and exchange it with the first

* number then doing this for other numbers except the first number Repeat

* this until all numbers are in order If you have any suggestion or problem

* please e mail to

*

* @author vivien Data:

*/

public class StraightSelectionSort {

/** The string containing the number wait for sorted */

public String numString = new String();

public Text numText;

public Text resText;

public Button btSort;

public Label errorLabel;

/** The flag to indicate if there is any error for inputed numbers */

public boolean hasError = false;

/** The arrayList containing the double numbers wait for sorted */

public ArrayListDouble numList = new ArrayListDouble();

public static void main(String[] args) {

StraightSelectionSort selectionSort = new StraightSelectionSort();

selectionSort createControl();

}

/**

* Create the control for the interface

*/

public void createControl() {

Display display = new Display();

Shell shell = new Shell(display);

shell setBounds( );

// Set Title

shell setText( Straight selection sort );

FormLayout layout = new FormLayout();

shell setLayout(layout);

FormData fd = new FormData();

// The Start Sort button

btSort = new Button(shell SWT NONE | SWT CENTER);

btSort setText( Start Sort );

fd = new FormData();

fd height = ;

fd top = new FormAttachment( );

fd left = new FormAttachment( );

btSort setLayoutData(fd);

// The Input numbers group

Group numGroup = new Group(shell SWT NONE);

numGroup setText( Input numbers: );

numGroup setLayout(layout);

fd = new FormData();

fd top = new FormAttachment( );

fd left = new FormAttachment( );

fd right = new FormAttachment( );

fd bottom = new FormAttachment(btSort );

numGroup setLayoutData(fd);

// Label for input numbers

Label numLabel = new Label(numGroup SWT WRAP);

numLabel

setText( Please input the numbers you want to sort: (Note: Numbers need to be seperated by space) );

fd = new FormData();

fd top = new FormAttachment( );

fd left = new FormAttachment( );

fd right = new FormAttachment( );

numLabel setLayoutData(fd);

// Text for input numbers

numText = new Text(numGroup SWT BORDER | SWT MULTI | SWT V_SCROLL

| SWT WRAP);

numText setToolTipText( Numbers need to be seperated by space );

fd = new FormData();

fd top = new FormAttachment(numLabel );

fd left = new FormAttachment( );

fd right = new FormAttachment( );

fd bottom = new FormAttachment( );

numText setLayoutData(fd);

// The results group

Group resGroup = new Group(shell SWT NONE);

resGroup setText( The results: );

resGroup setLayout(layout);

fd = new FormData();

fd top = new FormAttachment(btSort );

fd left = new FormAttachment( );

fd right = new FormAttachment( );

fd bottom = new FormAttachment( );

resGroup setLayoutData(fd);

// Label for results

Label resLabel = new Label(resGroup SWT WRAP);

resLabel

setText( The results after sorted are: (Note: Results are seperated by space) );

fd = new FormData();

fd top = new FormAttachment( );

fd left = new FormAttachment( );

fd right = new FormAttachment( );

resLabel setLayoutData(fd);

// Text for results

resText = new Text(resGroup SWT BORDER | SWT MULTI | SWT V_SCROLL

| SWT WRAP);

resText setToolTipText( Results are seperated by space );

resText setEditable(false);

fd = new FormData();

fd top = new FormAttachment(resLabel );

fd left = new FormAttachment( );

fd right = new FormAttachment( );

fd bottom = new FormAttachment( );

resText setLayoutData(fd);

// Label for showing error message

errorLabel = new Label(shell SWT NONE);

fd = new FormData();

fd top = new FormAttachment( );

fd left = new FormAttachment( );

fd right = new FormAttachment( );

fd bottom = new FormAttachment( );

errorLabel setLayoutData(fd);

errorLabel setForeground(display getSystemColor(SWT COLOR_RED));

// Listen to the numText change

numText addModifyListener(new ModifyListener() {

@Override

public void modifyText(ModifyEvent e) {

numString = numText getText() trim();

hasError = false;

}

});

// If press Return focus go to Start Sort button and start sort

numText addKeyListener(new KeyAdapter() {

@Override

public void keyPressed(KeyEvent e) {

if (e keyCode == \r ) {

e doit = false;

btSort setFocus();

startSort();

}

}

});

// Listen to the button selection

btSort addSelectionListener(new SelectionAdapter() {

public void widgetSelected(SelectionEvent e) {

startSort();

}

});

shell open();

while (!shell isDisposed()) {

if (!display readAndDispatch())

display sleep();

}

display dispose();

}

/**

* Get double values from string

*/

public void getDoubleFromString() {

int index = ;

// Split string using space

String[] splitedNumbers = numString split( );

if (numList size() != )

// Clear the arrayList for last used

numList clear();

for (int i = ; i splitedNumbers length; i++) {

if (splitedNumbers[i] trim() length() != ) {

try {

numList add(index++ Double valueOf(splitedNumbers[i]));

} catch (NumberFormatException e) {

setErrorMessage( Please input the correct numbers );

hasError = true;

break;

}

}

}

}

/**

* Start sort the string containing numbers waited for sort

*/

public void startSort() {

if (numString != null)

if (numString trim() length() != ) {

getDoubleFromString();

startStraightSelectionSort();

setResults();

} else {

setErrorMessage( Please input numbers );

hasError = true;

}

}

/**

* Set the results to the results group

*/

public void setResults() {

if (!hasError) {

String resString = new String();

for (int i = ; i numList size(); i++)

if (i != numList size() )

resString = resString + numList get(i) + ;

else

// If be the last string

resString = resString + numList get(i);

resText setText(resString);

// Clear errorLabel

errorLabel setText( );

}

}

/**

* Sort the numbers using Straight selection Sort algorithm

*/

public void startStraightSelectionSort() {

int minPosition = ;

for (int j = ; j numList size() ; j++) {

minPosition = j;

for (int i = j + ; i numList size(); i++) {

if (numList get(i) numList get(minPosition)) {

minPosition = i;

}

}

if (minPosition != j) {

// Exchange the minimum with the first number of the numbers

// waited for sort

double temp = numList get(j);

numList set(j numList get(minPosition));

numList set(minPosition temp);

}

}

}

/**

* Set the error message on the error Label

*

* @param errorString

*            The string used for set on the errorLabel

*/

public void setErrorMessage(String errorString) {

errorLabel setText(errorString);

// Clear the text of results

resText setText( );

hasError = true;

}

}

Black box Test Case:

)      All numbers are zero:

java快速排序简单代码

.example-btn{color:#fff;background-color:#5cb85c;border-color:#4cae4c}.example-btn:hover{color:#fff;background-color:#47a447;border-color:#398439}.example-btn:active{background-image:none}div.example{width:98%;color:#000;background-color:#f6f4f0;background-color:#d0e69c;background-color:#dcecb5;background-color:#e5eecc;margin:0 0 5px 0;padding:5px;border:1px solid #d4d4d4;background-image:-webkit-linear-gradient(#fff,#e5eecc 100px);background-image:linear-gradient(#fff,#e5eecc 100px)}div.example_code{line-height:1.4em;width:98%;background-color:#fff;padding:5px;border:1px solid #d4d4d4;font-size:110%;font-family:Menlo,Monaco,Consolas,"Andale Mono","lucida console","Courier New",monospace;word-break:break-all;word-wrap:break-word}div.example_result{background-color:#fff;padding:4px;border:1px solid #d4d4d4;width:98%}div.code{width:98%;border:1px solid #d4d4d4;background-color:#f6f4f0;color:#444;padding:5px;margin:0}div.code div{font-size:110%}div.code div,div.code p,div.example_code p{font-family:"courier new"}pre{margin:15px auto;font:12px/20px Menlo,Monaco,Consolas,"Andale Mono","lucida console","Courier New",monospace;white-space:pre-wrap;word-break:break-all;word-wrap:break-word;border:1px solid #ddd;border-left-width:4px;padding:10px 15px} 排序算法是《数据结构与算法》中最基本的算法之一。排序算法可以分为内部排序和外部排序，内部排序是数据记录在内存中进行排序，而外部排序是因排序的数据很大，一次不能容纳全部的排序记录，在排序过程中需要访问外存。常见的内部排序算法有：插入排序、希尔排序、选择排序、冒泡排序、归并排序、快速排序、堆排序、基数排序等。以下是快速排序算法：

快速排序是由东尼·霍尔所发展的一种排序算法。在平均状况下，排序 n 个项目要 Ο(nlogn) 次比较。在最坏状况下则需要 Ο(n2) 次比较，但这种状况并不常见。事实上，快速排序通常明显比其他 Ο(nlogn) 算法更快，因为它的内部循环（inner loop）可以在大部分的架构上很有效率地被实现出来。

快速排序使用分治法（Divide and conquer）策略来把一个串行（list）分为两个子串行（sub-lists）。

快速排序又是一种分而治之思想在排序算法上的典型应用。本质上来看，快速排序应该算是在冒泡排序基础上的递归分治法。

快速排序的名字起的是简单粗暴，因为一听到这个名字你就知道它存在的意义，就是快，而且效率高！它是处理大数据最快的排序算法之一了。虽然 Worst Case 的时间复杂度达到了 O(n?)，但是人家就是优秀，在大多数情况下都比平均时间复杂度为 O(n logn) 的排序算法表现要更好，可是这是为什么呢，我也不知道。好在我的强迫症又犯了，查了 N 多资料终于在《算法艺术与信息学竞赛》上找到了满意的答案：

快速排序的最坏运行情况是 O(n?)，比如说顺序数列的快排。但它的平摊期望时间是 O(nlogn)，且 O(nlogn) 记号中隐含的常数因子很小，比复杂度稳定等于 O(nlogn) 的归并排序要小很多。所以，对绝大多数顺序性较弱的随机数列而言，快速排序总是优于归并排序。

1. 算法步骤

从数列中挑出一个元素，称为 "基准"（pivot）;

重新排序数列，所有元素比基准值小的摆放在基准前面，所有元素比基准值大的摆在基准的后面（相同的数可以到任一边）。在这个分区退出之后，该基准就处于数列的中间位置。这个称为分区（partition）操作；

递归地（recursive）把小于基准值元素的子数列和大于基准值元素的子数列排序；

2. 动图演示

代码实现 JavaScript 实例 function quickSort ( arr , left , right ) {

var len = arr. length ,

    partitionIndex ,

    left = typeof left != 'number' ? 0 : left ,

    right = typeof right != 'number' ? len - 1 : right ;

if ( left

java怎么让数组的数字从大到小排序？

将数字从大到小排序的方法：

例如简一点的冒泡排序，将第一个数字和后面的数字逐个比较大小，如果小于，则互换位置，大于则不动。此时，第一个数为数组中的最大数。然后再将第二个数与后面的数逐个比较，以次类推。

示例代码如下： 

public class Test { 

public static void main(String[] args) { 

int [] array = {12,3,1254,235,435,236,25,34,23}; 

int temp; 

for (int i = 0; i  array.length; i++) { 

for (int j = i+1; j  array.length; j++) { 

if (array[i]  array[j]) { 

temp = array[i]; 

array[i] = array[j]; 

array[j] = temp; // 两个数交换位置 

} 

} 

} 

for (int i = 0; i  array.length; i++) { 

System.out.print(array[i]+"  "); 

} 

} 

}

数组对于每一门编程语言来说都是重要的数据结构之一，当然不同语言对数组的实现及处理也不尽相同。

Java 语言中提供的数组是用来存储固定大小的同类型元素。

你可以声明一个数组变量，如 numbers[100] 来代替直接声明 100 个独立变量 number0，number1，....，number99

扩展资料

Java中利用数组进行数字排序一般有4种方法：

1、选择排序是先将数组中的第一个数作为最大或最小数，然后通过循环比较交换最大数或最小数与一轮比较中第一个数位置进行排序。

2、冒泡排序也是先将数组中的第一个数作为最大或最小数，循环比较相邻两个数的大小，满足条件就互换位置，将最大数或最小数沉底。

3、快速排序法主要是运用Arrays类中的Arrays.sort方法（）实现。

4、插入排序是选择一个数组中的数据，通过不断的插入比较最后进行排序。

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