数据结构之数组Array_JAVA源代码及注意事项
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2024-01-18 21:45:16
数据结构之数组Array_JAVA注意事项NO.1/*忘记加private!!!!!数组data和数组元素个数size外界不可访问要变为私有private*/private E[] data;private int size;NO.2/*构造函数的写法记住data = (E[]) new Object[Capacity]注意:对于多类型的E要进行类型的转换Objective------>E*/ public Array(int Capacity) {...
数据结构之数组Array_JAVA
注意事项
NO.1
/*忘记加private!!!!!
数组data和数组元素个数size外界不可访问
要变为私有private
*/
private E[] data;
private int size;
NO.2
/*构造函数的写法记住
data = (E[]) new Object[Capacity]
注意:对于多类型的E
要进行类型的转换Objective------>E
*/
public Array(int Capacity) {
data = (E[]) new Object[Capacity];
size = 0;
}
NO.3
// 在index索引的位置插入一个新元素e
public void insert(int index,E e){
if(index < 0 || index > size)// 错误:size == getCapacity()!!!!!!!!!
throw new IllegalArgumentException("insert is false");
if(size == data.length)
resize(2 * data.length);
for(int i = size - 1; i >= index ; i --)
data[i + 1] = data[i];
// for (int i = data.length; i > index; i--) {
// data[i] = data[i - 1];
// }这里写的不对,data.length!=size
data[index]=e;
size++;
}
size:数组元素的个数
.length:数组的长度
Capacity:数组的容量=长度
NO.4
/*记住抛出异常的格式
*/
if(index < 0 || index >= size)
throw new IllegalArgumentException("Set failed. Index is illegal.");
NO.5
/*重写toString方法的格式
*/
@Override
public String toString(){
StringBuilder res = new StringBuilder();
源代码
Array类
public class Array<E> {
private E[] data;
private int size;
// 构造函数,传入数组的容量capacity构造Array
public Array(int Capacity) {
data = (E[]) new Object[Capacity];
size = 0;
}
// 无参数的构造函数,默认数组的容量capacity=10
public Array(){
this(10);
}
// 获取数组的容量
public int getCapacity(){
return data.length;
}
// 获取数组中的元素个数
public int getSize(){
return size;
}
// 返回数组是否为空
public boolean isEmpty(){
return size==0;
}
// 在index索引的位置插入一个新元素e
public void insert(int index,E e){
if(index < 0 || index > size)
throw new IllegalArgumentException("insert is false");
if(size == data.length)
resize(2 * data.length);
for(int i = size - 1; i >= index ; i --)
data[i + 1] = data[i];
data[index]=e;
size++;
}
// 向所有元素后添加一个新元素
public void addLast(E e){
insert(size,e);
}
// 在所有元素前添加一个新元素
public void addFirst(E e){
insert(0,e);
}
// 获取index索引位置的元素
public E get(int index){
if(index < 0 || index >= size)
throw new IllegalArgumentException("Get failed. Index is illegal.");
return data[index];
}
// 修改index索引位置的元素为e
public void set(int index,E e){
if(index < 0 || index >= size)
throw new IllegalArgumentException("Set failed. Index is illegal.");
data[index]=e;
}
// 查找数组中是否有元素e
public boolean contains(E e){
for (int i = 0; i < size; i++) {
if(data[i].equals(e))
return true;
}
return false;
}
// 查找数组中元素e所在的索引,如果不存在元素e,则返回-1
public int find(E e){
for (int i = 0; i < size; i++) {
if(data[i].equals(e))
return i;
}
return -1;
}
// 从数组中删除index位置的元素, 返回删除的元素
public E delete(int index){
if(index < 0 || index >= size)
throw new IllegalArgumentException("Set failed. Index is illegal.");
E temp = data[index];
for(int i = index ; i < size - 1; i++){
data[i]=data[i+1];
}
data[size-1]=null;
size--;
if(size == data.length / 4 && data.length / 2 != 0)
resize(data.length / 2);
return temp;
}
// 从数组中删除第一个元素, 返回删除的元素
public E deleteFirst(){
return delete(0);
}
// 从数组中删除最后一个元素, 返回删除的元素
public E deleteLast(){
return delete(size-1);
}
// 从数组中删除元素e
public void deleteElement(E e){
int index=find(e);
if(index!=-1)
delete(index);
}
@Override
public String toString(){
StringBuilder res = new StringBuilder();
res.append(String.format("Array : size = %d , capacity = %d\n", size, data.length));
res.append("[");
for (int i = 0; i < size; i++) {
res.append(data[i]);
if(i != size - 1)
res.append(", ");
}
res.append("]");
return res.toString();
}
// 将数组空间的容量变成newCapacity大小
private void resize(int newCapacity){
E[] newData = (E[])new Object[newCapacity];
for(int i = 0 ; i < size ; i ++)
newData[i] = data[i];
data = newData;
}
}
主函数main
public class main {
public static void main(String[] args) {
Array<Integer> arr = new Array<>();
for(int i = 0 ; i < 10 ; i ++)
arr.addLast(i);
System.out.println(arr);
arr.insert(1, 100);
System.out.println(arr);
arr.addFirst(-1);
System.out.println(arr);
arr.delete(2);
System.out.println(arr);
arr.deleteElement(4);
System.out.println(arr);
arr.deleteFirst();
System.out.println(arr);
for(int i = 0 ; i < 4 ; i ++){
arr.deleteFirst();
System.out.println(arr);
}
}
}
结果
"C:\Program Files\Java\jdk14\bin\java.exe" "-javaagent:C:\Program Files\JetBrains\IntelliJ IDEA 2020.2\lib\idea_rt.jar=64795:C:\Program Files\JetBrains\IntelliJ IDEA 2020.2\bin" -Dfile.encoding=UTF-8 -classpath C:\Users\12778\IdeaProjects\first\out\production\Array com.Array.main
Array : size = 10 , capacity = 10
[0, 1, 2, 3, 4, 5, 6, 7, 8, 9]
Array : size = 11 , capacity = 20
[0, 100, 1, 2, 3, 4, 5, 6, 7, 8, 9]
Array : size = 12 , capacity = 20
[-1, 0, 100, 1, 2, 3, 4, 5, 6, 7, 8, 9]
Array : size = 11 , capacity = 20
[-1, 0, 1, 2, 3, 4, 5, 6, 7, 8, 9]
Array : size = 10 , capacity = 20
[-1, 0, 1, 2, 3, 5, 6, 7, 8, 9]
Array : size = 9 , capacity = 20
[0, 1, 2, 3, 5, 6, 7, 8, 9]
Array : size = 8 , capacity = 20
[1, 2, 3, 5, 6, 7, 8, 9]
Array : size = 7 , capacity = 20
[2, 3, 5, 6, 7, 8, 9]
Array : size = 6 , capacity = 20
[3, 5, 6, 7, 8, 9]
Array : size = 5 , capacity = 10
[5, 6, 7, 8, 9]
Process finished with exit code 0
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