package com.company;
public class MyArrayList {
private Object[] mData = new Object[0];
public void add(Object object){
Object[] newData = new Object[mData.length + 1];
for(int i = 0; i < mData.length; i ++){
newData[i] = mData[i];
}
newData[mData.length] = object;
mData = newData;
}
public Object get(int k){
return mData[k];
}
public void printAll(){
for(int i = 0; i < mData.length; i ++)
System.out.print(mData[i] + " ");
System.out.println("\n");
}
public static void main(String[] args){
MyArrayList myArrayList = new MyArrayList();
myArrayList.add(new Integer(4));
myArrayList.printAll();
myArrayList.add(5);
myArrayList.add(6);
myArrayList.printAll();
}
}package com.company;
public class Arrays {
// Overview: This class provides a number of standalone procedure that
// are useful for manipulating arrays of ints.
public static int search(int[] a, int x){
//Effects: If x is in a, return an index where x is stored;
//otherwise, return -1.
if (a == null) return -1;
for(int i = 0; i < a.length; i ++)
if (a[i] == x) return i;
return -1;
}
}package com.company;
public class Main {
public static void sort(int[] a){
// Modifies: a
// Effects: Sorts a[0], ..., a[a.length - 1] into ascending order.
if (a == null) return;
quickSort(a, 0, a.length - 1);
}
private static void quickSort(int[] a, int low, int high) {
//Requires: a is not null and 0 <= low & high < a.length
//Modifes: a
//Effects: Sort a[low], a[low + 1], ..., a[high] into ascending order.
if (low >= high) return;
int mid = partition(a, low, high);
quickSort(a, low, mid);
quickSort(a, mid + 1, high);
}
private static int partition(int[] a, int i, int j) {
//Requires: a is not null and 0 <= i < j < a.length
//Modifies: a
//Effects: Reorder the elements in a into two contiguos groups,
//a[i], ..., a[res] and a[res + 1], ..., a[j], such that each
// element in the second group is at least as large as each
// element in the first group. Return res.
int x = a[i];
while (true){
while (a[j] > x) j --;
while (a[i] < x) i ++;
if (i < j){ //ned to swap
int temp = a[i]; a[i] = a[j]; a[j] = temp;
j --; i ++;
} else
return j;}
}
public static void main(String[] args) {
// write your code here
int intArray[] = new int[8];
for(int i = 0; i < intArray.length; i ++)
intArray[i] = (2 * i) % 8;
for(int i = 0; i < intArray.length; i ++)
System.out.print(intArray[i] + " ");
System.out.println(" ");
sort(intArray);
for(int i = 0; i < intArray.length; i ++)
System.out.print(intArray[i] + " ");
}
}
```java
References:
[1] Program Development in Java, Barbara Liskov and John Guttag.
[2] https://docs.oracle.com/javase/tutorial/java/generics/