Programs on Vector and ArrayList with proper comments for better understanding

Author: VikramGujar

src/com/lab/dec_30/Test1.java

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+package com.lab.dec_30;
+
+import java.util.*;
+class Test1
+{
+	public static void main(String args[])
+	{
+		// here we are creating vector class object
+		// constructor is taking [ int initialCapacity, int capacityIncrement ]
+		Vector obj = new Vector(4,2); 
+		
+		// This type of constructor is removed [ Deprecated ] from integer class since JAVA-9
+		obj.addElement(new Integer(3));
+		obj.addElement(new Integer(2));
+		obj.addElement(new Integer(5));
+		
+		// This line will print element which is at 1 index [ 2 ]
+		// Vector is internally array thats why it adds elements as per indexes 
+		System.out.println(obj.elementAt(1));
+	}
+}

src/com/lab/dec_30/Test10.java

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+package com.lab.dec_30;
+
+import java.util.ArrayList;
+public class Test10 
+{
+	public static void main(String[] args)
+	{
+ 
+		ArrayList<String> list = new ArrayList<String>();
+ 
+		list.add(null);		// [null]
+		list.add(0, "A");	// [A, null]
+		list.add(2, "B");	// [A, null, B]
+		list.add(1, "C");	// [A, C, null, B]
+ 
+		// Will print the list
+		// [A, C, null, B]
+		System.out.println(list);
+	}
+}
+

src/com/lab/dec_30/Test11.java

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+package com.lab.dec_30;
+
+import java.util.ArrayList;
+public class Test11 
+{
+	public static void main(String[] args)
+	{
+ 
+		ArrayList<String> list = new ArrayList<String>();
+ 
+		list.add(null);		// [null]
+		list.add(0, "A");	// [A, null]
+		list.add(null);		// [A, null, null]
+		list.add(2, "B");	// [A, null, B, null]
+		list.add("20");		// [A, null, B, null, 20]
+		list.add(1, "C");	// [A, C, null, B, null, 20]
+ 
+		// Will print the list
+		// [A, C, null, B, null, 20]
+		System.out.println(list);
+ }
+}
+

src/com/lab/dec_30/Test12.java

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+package com.lab.dec_30;
+
+import java.util.ArrayList;
+
+public class Test12 
+{
+	public static void main(String[] args)
+	{
+		// ArrayList of type String
+		ArrayList<String> list = new ArrayList<>();
+ 
+		// List is type String can't hold Integer objects
+		/*
+		list.add(12);
+		list.add(16);
+		list.add(34);
+		list.add(78);
+		list.remove(12);
+		*/
+		
+		System.out.println(list);
+	}
+}
+

src/com/lab/dec_30/Test13.java

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+package com.lab.dec_30;
+
+import java.util.ArrayList;
+
+public class Test13 
+{
+	public static void main(String[] args)
+	{
+ 
+		ArrayList<String> list = new ArrayList<>();
+		
+		// List type String
+		// Can't hold char type data
+		/*
+		list.add('a');
+		list.add('b');
+		list.add('c');
+		list.add('d');
+		list.remove('c');
+		*/
+ 
+		System.out.println(list);
+	}
+}

src/com/lab/dec_30/Test14.java

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+package com.lab.dec_30;
+
+import java.util.ArrayList;
+public class Test14 
+{
+	public static void main(String[] args)
+	{
+ 
+		ArrayList<String> list = new ArrayList<>();
+ 
+		// ArrayList is type String
+		// Can't hold Integer type object
+		/*
+		list.add(12);
+		list.add(16);
+		list.add(34);
+		list.add(78);
+		list.remove(Integer.valueOf(16));
+		*/
+		
+		System.out.println(list);
+	}
+}
+

src/com/lab/dec_30/Test2.java

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+package com.lab.dec_30;
+
+import java.util.*;
+
+public class Test2 
+{
+	public static void main(String args[]) 
+	{
+		//This is calling constructor Vector(int initialCapacity, int capacityIncrement)
+		Vector obj = new Vector(4,2);
+		// InitialCapacity = 4
+		// CapacityIncreament = 2
+		
+		// Here we are adding elements to vector
+		obj.addElement(new Integer(3));
+		obj.addElement(new Integer(2));
+		obj.addElement(new Integer(5));
+		
+		// Capacity will be printed [ 4 ]
+		System.out.println(obj.capacity());
+	}
+}

src/com/lab/dec_30/Test3.java

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+package com.lab.dec_30;
+import java.util.*;
+
+public class Test3 
+{
+	 public static void main(String args[]) 
+	 {
+	 Vector obj = new Vector(4,2);
+	 
+	 obj.addElement(new Integer(3));
+	 obj.addElement(new Integer(2));
+	 obj.addElement(new Integer(6));
+	 
+	 // Here we are inserting element 8 at position 2
+	 obj.insertElementAt(new Integer(8), 2);
+	 
+	 // This will print toString method of Vector class
+	 // [ 3, 2, 8, 6 ]
+	 System.out.println(obj);
+	 }
+	 
+}

src/com/lab/dec_30/Test4.java

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+package com.lab.dec_30;
+import java.util.*;
+
+public class Test4 
+{
+	public static void main(String args[]) 
+	{
+		Vector obj = new Vector(4,2);
+		
+		obj.addElement(new Integer(3));
+		obj.addElement(new Integer(2));
+		obj.addElement(new Integer(5));
+		
+		// here remove all will remove all elements from vector
+		obj.removeAll(obj);
+		
+		// isEmpty method will check weather the vector is empty of not
+		// true
+		System.out.println(obj.isEmpty());
+		
+		// will print empty array 
+		// [ ]
+		System.out.println(obj);
+	}
+}
+
+
+

src/com/lab/dec_30/Test5.java

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+package com.lab.dec_30;
+
+import java.util.*;
+public class Test5 
+{
+	public static void main(String args[]) 
+	{
+		// Array of lenght 5 will be created
+		int array[] = new int [5];
+		
+		
+		// array will be filled with 5-1 values 
+		// [ 5, 4, 3, 2, 1 ]
+		for (int i = 5; i > 0; i--)
+			array[5-i] = i;
+		
+		
+		/*
+		 public static void fill(int[] a, int fromIndex, int toIndex, int val) 
+		 {
+        	rangeCheck(a.length, fromIndex, toIndex);
+        	for (int i = fromIndex; i < toIndex; i++)
+            a[i] = val;
+    	 }
+		 */
+		
+		// This fill method is taking parameters
+		// 1. Array[]	=> array
+		// 2. fromIndex => 1
+		// 3. toIndex   => 4
+		// 4. value		=> 8
+		Arrays.fill(array, 1, 4, 8);
+		// The above method will fill array with value 8 
+		// from index 1 to index 4 that is [1], [2], [3]
+		// array [ 5, 8, 8, 8, 1 ]
+		
+		
+		for (int i = 0; i < 5 ; i++)
+			System.out.print(array[i]+" ");
+}
+}

src/com/lab/dec_30/Test6.java

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+package com.lab.dec_30;
+
+import java.util.*;
+public class Test6  
+{
+	public static void main(String args[])
+	{
+		// Creating objects for ArrayList
+		ArrayList obj1 = new ArrayList();
+		ArrayList obj2 = new ArrayList();
+		
+		// Adding objects to ArrayList
+		obj1.add("A");
+		obj1.add("B");
+		obj2.add("A");
+		
+		// Adding "B" at index 1
+		obj2.add(1, "B");
+		
+		// Will check that the obj1 is equals to obj2 or not
+		// True
+		System.out.println(obj1.equals(obj2));
+	}
+}
+
+
+

src/com/lab/dec_30/Test7.java

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+package com.lab.dec_30;
+import java.util.ArrayList;
+import java.util.List;
+
+public class Test7 
+{
+	public static void main(String[] args)
+	{
+		List<String> list = new ArrayList<String>();
+		
+		list.add("Patna");			// ["Patna"]
+		list.add(0, "New York");	// ["New York", "Patna"]
+		list.add("Mumbai");			// ["New York", "Patna", "Mumbai"]
+		list.add(2, "Sydney");		// ["New York", "Patna", "Sydney, "Mumbai"]
+		
+		//This line will print the list
+		// ["New York", "Patna", "Sydney, "Mumbai"]
+		System.out.println(list);
+	}
+}
+

src/com/lab/dec_30/Test8.java

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+package com.lab.dec_30;
+
+import java.util.ArrayList;
+import java.util.List;
+
+public class Test8 
+{
+	public static void main(String[] args)
+	{
+		// Creating ArrayList Object
+		List<String> list = new ArrayList<String>();
+		
+		
+		list.add("Orange");		// list ["Orange"]
+		list.add(0, "Banana");	// list ["Banana", "Orange"]
+ 
+		//New ArrayList object created i.e arList
+		ArrayList<String> arList = new ArrayList<>();
+		
+		arList.add("Apple");	// arList ["Apple"]
+		list.add("Grapes");		// list ["Banana", "Orange", "Grapes"]
+		
+		// All elements of arList will be append to list
+		// list ["Banana", "Orange", "Grapes"] + arList ["Apple"]
+		list.addAll(3, arList);	// list ["Banana", "Orange", "Grapes" ,"Apple"]
+		
+		// ["Banana", "Orange", "Grapes" ,"Apple"]
+		System.out.println(list);
+	}
+}
+

src/com/lab/dec_30/Test9.java

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+package com.lab.dec_30;
+
+import java.util.ArrayList;
+public class Test9 
+{
+	public static void main(String[] args)
+	{
+		ArrayList<String> list = new ArrayList<String>();
+ 
+		// null added to 0th index
+		list.add(null);		// [null]
+		
+		list.add(0, "A");	// [null, "A"]
+		
+		// Exception will occur
+		// i.e  [ java.lang.IndexOutOfBoundsException ]
+		list.add(3, "B");	// We can not insert element at 3 without inserting at 2
+		list.add(1, "C");
+ 
+		System.out.println(list);
+	}
+}