From 921615945e32ed20de127e50497ae70096dc6649 Mon Sep 17 00:00:00 2001
From: Ceiling_roof <48134466+ResilientSpring@users.noreply.github.com>
Date: Mon, 2 Oct 2023 22:25:57 +0800
Subject: [PATCH 01/38] Committed on or around 2023/10/02

---
 .../Interface/Using_Interface_References.java | 21 +++++++++++++++++++
 1 file changed, 21 insertions(+)
 create mode 100644 Chapter8/Interface/Using_Interface_References.java

diff --git a/Chapter8/Interface/Using_Interface_References.java b/Chapter8/Interface/Using_Interface_References.java
new file mode 100644
index 0000000..13eebb9
--- /dev/null
+++ b/Chapter8/Interface/Using_Interface_References.java
@@ -0,0 +1,21 @@
+package Interface;
+
+// An interface specifies what to do, not how to do.
+interface Seriess{
+	int getNext();
+	void reset();
+	void setStart(int x);
+}
+
+class ByTwoss{
+	
+}
+
+public class Using_Interface_References {
+
+	public static void main(String[] args) {
+		// TODO Auto-generated method stub
+
+	}
+
+}

From facb3e5fbfe51b48181da4b33cbf03bcca01827d Mon Sep 17 00:00:00 2001
From: Ceiling_roof <48134466+ResilientSpring@users.noreply.github.com>
Date: Mon, 2 Oct 2023 22:45:14 +0800
Subject: [PATCH 02/38] Committed on or around 2023/10/02

---
 .../Interface/Using_Interface_References.java | 28 ++++++++++++++++++-
 1 file changed, 27 insertions(+), 1 deletion(-)

diff --git a/Chapter8/Interface/Using_Interface_References.java b/Chapter8/Interface/Using_Interface_References.java
index 13eebb9..b9c38bb 100644
--- a/Chapter8/Interface/Using_Interface_References.java
+++ b/Chapter8/Interface/Using_Interface_References.java
@@ -7,7 +7,33 @@ interface Seriess{
 	void setStart(int x);
 }
 
-class ByTwoss{
+class ByTwoss implements Seriess{
+	
+	int start;
+	int value;
+	
+	public ByTwoss() {
+		start = 0;
+		value = 0;
+	}
+
+	@Override
+	public int getNext() {
+		value += 2;
+		return value;
+	}
+
+	@Override
+	public void reset() {
+		value = start;
+		
+	}
+
+	@Override
+	public void setStart(int x) {
+		// TODO Auto-generated method stub
+		
+	}
 	
 }
 

From 59c52d6171b873e4a8c1e8ce372a42afb3568c99 Mon Sep 17 00:00:00 2001
From: Ceiling_roof <48134466+ResilientSpring@users.noreply.github.com>
Date: Mon, 2 Oct 2023 22:46:58 +0800
Subject: [PATCH 03/38] Committed on or around 2023/10/02

---
 Chapter8/Interface/Using_Interface_References.java | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/Chapter8/Interface/Using_Interface_References.java b/Chapter8/Interface/Using_Interface_References.java
index b9c38bb..e921e50 100644
--- a/Chapter8/Interface/Using_Interface_References.java
+++ b/Chapter8/Interface/Using_Interface_References.java
@@ -32,7 +32,8 @@ public void reset() {
 	@Override
 	public void setStart(int x) {
 		// TODO Auto-generated method stub
-		
+		start = x;
+		value = x;
 	}
 	
 }

From 072f35af22ce02ccf05b559a6f76f09726b9da8c Mon Sep 17 00:00:00 2001
From: Ceiling_roof <48134466+ResilientSpring@users.noreply.github.com>
Date: Mon, 2 Oct 2023 22:49:31 +0800
Subject: [PATCH 04/38] Committed on or around 2023/10/02

---
 Chapter8/Interface/Using_Interface_References.java | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/Chapter8/Interface/Using_Interface_References.java b/Chapter8/Interface/Using_Interface_References.java
index e921e50..fbcec26 100644
--- a/Chapter8/Interface/Using_Interface_References.java
+++ b/Chapter8/Interface/Using_Interface_References.java
@@ -42,6 +42,8 @@ public class Using_Interface_References {
 
 	public static void main(String[] args) {
 		// TODO Auto-generated method stub
+		
+		
 
 	}
 

From 9dcc395be203661f30e6717fe395ae13670190eb Mon Sep 17 00:00:00 2001
From: Ceiling_roof <48134466+ResilientSpring@users.noreply.github.com>
Date: Mon, 2 Oct 2023 22:51:36 +0800
Subject: [PATCH 05/38] Committed on or around 2023/10/02

---
 .../Interface/Using_Interface_References.java | 32 +++++++++++++++++++
 1 file changed, 32 insertions(+)

diff --git a/Chapter8/Interface/Using_Interface_References.java b/Chapter8/Interface/Using_Interface_References.java
index fbcec26..8a7689b 100644
--- a/Chapter8/Interface/Using_Interface_References.java
+++ b/Chapter8/Interface/Using_Interface_References.java
@@ -38,6 +38,38 @@ public void setStart(int x) {
 	
 }
 
+
+class ByThreess implements Seriess{
+	
+	int start;
+	int value;
+	
+	public ByThreess() {
+		start = 0;
+		value = 0;
+	}
+
+	@Override
+	public int getNext() {
+		// TODO Auto-generated method stub
+		return 0;
+	}
+
+	@Override
+	public void reset() {
+		// TODO Auto-generated method stub
+		
+	}
+
+	@Override
+	public void setStart(int x) {
+		// TODO Auto-generated method stub
+		
+	}
+	
+}
+
+
 public class Using_Interface_References {
 
 	public static void main(String[] args) {

From 97c2b48e42aff7bdc00c71394e89e1fa7c92159b Mon Sep 17 00:00:00 2001
From: Ceiling_roof <48134466+ResilientSpring@users.noreply.github.com>
Date: Mon, 2 Oct 2023 22:54:16 +0800
Subject: [PATCH 06/38] Committed on or around 2023/10/02

---
 Chapter8/Interface/Using_Interface_References.java | 7 ++++---
 1 file changed, 4 insertions(+), 3 deletions(-)

diff --git a/Chapter8/Interface/Using_Interface_References.java b/Chapter8/Interface/Using_Interface_References.java
index 8a7689b..2c1d173 100644
--- a/Chapter8/Interface/Using_Interface_References.java
+++ b/Chapter8/Interface/Using_Interface_References.java
@@ -51,8 +51,10 @@ public ByThreess() {
 
 	@Override
 	public int getNext() {
-		// TODO Auto-generated method stub
-		return 0;
+		
+		value += 3;
+		
+		return value;
 	}
 
 	@Override
@@ -73,7 +75,6 @@ public void setStart(int x) {
 public class Using_Interface_References {
 
 	public static void main(String[] args) {
-		// TODO Auto-generated method stub
 		
 		
 

From 98c333b5c718ab89b66c27f0202155315e26ad26 Mon Sep 17 00:00:00 2001
From: Ceiling_roof <48134466+ResilientSpring@users.noreply.github.com>
Date: Mon, 2 Oct 2023 22:56:32 +0800
Subject: [PATCH 07/38] Committed on or around 2023/10/02

---
 Chapter8/Interface/Using_Interface_References.java | 5 +++--
 1 file changed, 3 insertions(+), 2 deletions(-)

diff --git a/Chapter8/Interface/Using_Interface_References.java b/Chapter8/Interface/Using_Interface_References.java
index 2c1d173..7f6af18 100644
--- a/Chapter8/Interface/Using_Interface_References.java
+++ b/Chapter8/Interface/Using_Interface_References.java
@@ -60,13 +60,14 @@ public int getNext() {
 	@Override
 	public void reset() {
 		// TODO Auto-generated method stub
-		
+		value = start;
 	}
 
 	@Override
 	public void setStart(int x) {
 		// TODO Auto-generated method stub
-		
+		start = x;
+		value = x;
 	}
 	
 }

From 6cf58336c7fa0c2ba54df7ad4c9d6ec007354c69 Mon Sep 17 00:00:00 2001
From: Ceiling_roof <48134466+ResilientSpring@users.noreply.github.com>
Date: Mon, 2 Oct 2023 23:06:07 +0800
Subject: [PATCH 08/38] Committed on or around 2023/10/02

---
 Chapter8/Interface/Using_Interface_References.java | 14 ++++++++++++++
 1 file changed, 14 insertions(+)

diff --git a/Chapter8/Interface/Using_Interface_References.java b/Chapter8/Interface/Using_Interface_References.java
index 7f6af18..468bfb2 100644
--- a/Chapter8/Interface/Using_Interface_References.java
+++ b/Chapter8/Interface/Using_Interface_References.java
@@ -77,7 +77,21 @@ public class Using_Interface_References {
 
 	public static void main(String[] args) {
 		
+		ByTwoss twoOb = new ByTwoss();
+		ByThreess threeOb = new ByThreess();
+		Seriess ob;
 		
+		for (int i = 0; i < 5; i++) {
+			
+			ob = twoOb;
+			
+			System.out.println("Next ByTwoss value is " + ob.getNext());
+			
+			ob = threeOb;
+			
+			System.out.println("Next ByThreesb value is " + ob.getNext());
+			
+		}
 
 	}
 

From 6ab7e4c684546bb877fc74faef579779cb5672d8 Mon Sep 17 00:00:00 2001
From: Ceiling_roof <48134466+ResilientSpring@users.noreply.github.com>
Date: Mon, 2 Oct 2023 23:08:30 +0800
Subject: [PATCH 09/38] Committed on or around 2023/10/02

---
 Chapter8/Interface/Using_Interface_References.java | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/Chapter8/Interface/Using_Interface_References.java b/Chapter8/Interface/Using_Interface_References.java
index 468bfb2..fd89725 100644
--- a/Chapter8/Interface/Using_Interface_References.java
+++ b/Chapter8/Interface/Using_Interface_References.java
@@ -85,11 +85,11 @@ public static void main(String[] args) {
 			
 			ob = twoOb;
 			
-			System.out.println("Next ByTwoss value is " + ob.getNext());
+			System.out.println("Next ByTwos value is " + ob.getNext());
 			
 			ob = threeOb;
 			
-			System.out.println("Next ByThreesb value is " + ob.getNext());
+			System.out.println("Next ByThrees value is " + ob.getNext());
 			
 		}
 

From 8f9ca42b86e8f055ae39d9374749891ef5f29f02 Mon Sep 17 00:00:00 2001
From: Ceiling_roof <48134466+ResilientSpring@users.noreply.github.com>
Date: Mon, 2 Oct 2023 23:44:26 +0800
Subject: [PATCH 10/38] Committed on or around 2023/10/02

---
 Chapter7/IncompatibleRef.java | 2 --
 1 file changed, 2 deletions(-)

diff --git a/Chapter7/IncompatibleRef.java b/Chapter7/IncompatibleRef.java
index aa45591..84ceb56 100644
--- a/Chapter7/IncompatibleRef.java
+++ b/Chapter7/IncompatibleRef.java
@@ -1,5 +1,3 @@
-import java.awt.PrintGraphics;
-
 // This will not compile 
 class X {
 	int a;

From 43dfb3d9831483d03feeec23b994c2f4bb60d308 Mon Sep 17 00:00:00 2001
From: Ceiling_roof <48134466+ResilientSpring@users.noreply.github.com>
Date: Mon, 2 Oct 2023 23:52:14 +0800
Subject: [PATCH 11/38] Committed on or around 2023/10/02

---
 Chapter7/IncompatibleRef.java | 27 ++++++++++++++-------------
 1 file changed, 14 insertions(+), 13 deletions(-)

diff --git a/Chapter7/IncompatibleRef.java b/Chapter7/IncompatibleRef.java
index 84ceb56..c161811 100644
--- a/Chapter7/IncompatibleRef.java
+++ b/Chapter7/IncompatibleRef.java
@@ -1,36 +1,37 @@
 // This will not compile 
 class X {
+
 	int a;
-	
+
 	X(int i) {
 		a = i;
 	}
 }
 
 class Y {
-	int a ;
-	
-	Y(int i){
+
+	int a;
+
+	Y(int i) {
 		a = i;
 	}
-	
-}
 
+}
 
 public class IncompatibleRef {
 
 	public static void main(String[] args) {
 		// TODO Auto-generated method stub
-		
+
 		X x = new X(10);
-		
+
 		X x2;
-		
+
 		Y y = new Y(5);
-		
-		x2 = x;  // Ok, both of same type. 
-		
-		x2 = y; // Error, not of same type. 
+
+		x2 = x; // Ok, both of same type.
+
+		x2 = y; // Error, not of same type.
 
 	}
 

From 90575cb09b02bd7a4d1a267feec1ee51c495e978 Mon Sep 17 00:00:00 2001
From: Ceiling_roof <48134466+ResilientSpring@users.noreply.github.com>
Date: Tue, 3 Oct 2023 00:57:12 +0800
Subject: [PATCH 12/38] Committed on or around 2023/10/03

---
 Chapter7/theoretical/SupSubRef.java | 47 +++++++++++++++++++++++++++++
 1 file changed, 47 insertions(+)
 create mode 100644 Chapter7/theoretical/SupSubRef.java

diff --git a/Chapter7/theoretical/SupSubRef.java b/Chapter7/theoretical/SupSubRef.java
new file mode 100644
index 0000000..bcb9efb
--- /dev/null
+++ b/Chapter7/theoretical/SupSubRef.java
@@ -0,0 +1,47 @@
+package theoretical;
+
+//A superclass reference can refer to a subclass object. 
+
+class X2 {
+	int a;
+	
+	public X2(int i) {
+		// TODO Auto-generated constructor stub
+		
+		a = i;
+	}
+}
+
+class Y2 extends X2 {
+	int b;
+	
+	public Y2(int i, int j) {
+		// TODO Auto-generated constructor stub
+		super(j);
+		b = i;
+	}
+}
+
+public class SupSubRef {
+
+	public static void main(String[] args) {
+		
+		X2 x = new X2(10);
+		X2 x2;
+		Y2 y = new Y2(5, 6);
+		
+		x2 = x; // OK, both of same type.
+		System.out.println("X2.a: " + x2.a);
+		System.out.println("x.a: " + x.a);
+		
+		x2 = y;  // still ok because Y2 is derived from X2. Both of somewhat same type.
+		System.out.println("X2.a: " + x2.a);
+		
+		// X references know only about X members
+		x2.a = 19;  // OK
+// 		x2.b = 27;  // Error, X does not have a b member. 
+
+		
+	}
+
+}

From 2b760344ef5b00663a84c3ce631b599d7d773aca Mon Sep 17 00:00:00 2001
From: Ceiling_roof <48134466+ResilientSpring@users.noreply.github.com>
Date: Tue, 3 Oct 2023 00:59:26 +0800
Subject: [PATCH 13/38] Committed on or around 2023/10/03

---
 Chapter7/theoretical/SupSubRef.java | 14 +++++++-------
 1 file changed, 7 insertions(+), 7 deletions(-)

diff --git a/Chapter7/theoretical/SupSubRef.java b/Chapter7/theoretical/SupSubRef.java
index bcb9efb..ba3032f 100644
--- a/Chapter7/theoretical/SupSubRef.java
+++ b/Chapter7/theoretical/SupSubRef.java
@@ -2,20 +2,20 @@
 
 //A superclass reference can refer to a subclass object. 
 
-class X2 {
+class X {
 	int a;
 	
-	public X2(int i) {
+	public X(int i) {
 		// TODO Auto-generated constructor stub
 		
 		a = i;
 	}
 }
 
-class Y2 extends X2 {
+class Y extends X {
 	int b;
 	
-	public Y2(int i, int j) {
+	public Y(int i, int j) {
 		// TODO Auto-generated constructor stub
 		super(j);
 		b = i;
@@ -26,9 +26,9 @@ public class SupSubRef {
 
 	public static void main(String[] args) {
 		
-		X2 x = new X2(10);
-		X2 x2;
-		Y2 y = new Y2(5, 6);
+		X x = new X(10);
+		X x2;
+		Y y = new Y(5, 6);
 		
 		x2 = x; // OK, both of same type.
 		System.out.println("X2.a: " + x2.a);

From c47d68e82a243eebebf4962fd266fde0bb8082f9 Mon Sep 17 00:00:00 2001
From: Ceiling_roof <48134466+ResilientSpring@users.noreply.github.com>
Date: Tue, 3 Oct 2023 01:05:13 +0800
Subject: [PATCH 14/38] Committed on or around 2023/10/03

---
 Chapter7/theoretical/SupSubRef.java | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/Chapter7/theoretical/SupSubRef.java b/Chapter7/theoretical/SupSubRef.java
index ba3032f..b672a1a 100644
--- a/Chapter7/theoretical/SupSubRef.java
+++ b/Chapter7/theoretical/SupSubRef.java
@@ -34,7 +34,7 @@ public static void main(String[] args) {
 		System.out.println("X2.a: " + x2.a);
 		System.out.println("x.a: " + x.a);
 		
-		x2 = y;  // still ok because Y2 is derived from X2. Both of somewhat same type.
+		x2 = y;  // still ok because Y is derived from X.
 		System.out.println("X2.a: " + x2.a);
 		
 		// X references know only about X members

From bc3f05dfc4e0fd06999bd6355d1a9d28cbf66457 Mon Sep 17 00:00:00 2001
From: Ceiling_roof <48134466+ResilientSpring@users.noreply.github.com>
Date: Tue, 3 Oct 2023 01:08:03 +0800
Subject: [PATCH 15/38] Committed on or around 2023/10/03

---
 Chapter7/theoretical/SupSubRef.java | 25 +++++++++++++------------
 1 file changed, 13 insertions(+), 12 deletions(-)

diff --git a/Chapter7/theoretical/SupSubRef.java b/Chapter7/theoretical/SupSubRef.java
index b672a1a..e735611 100644
--- a/Chapter7/theoretical/SupSubRef.java
+++ b/Chapter7/theoretical/SupSubRef.java
@@ -3,45 +3,46 @@
 //A superclass reference can refer to a subclass object. 
 
 class X {
+
 	int a;
-	
+
 	public X(int i) {
-		// TODO Auto-generated constructor stub
-		
 		a = i;
 	}
 }
 
+
 class Y extends X {
+
 	int b;
-	
+
 	public Y(int i, int j) {
-		// TODO Auto-generated constructor stub
+		
 		super(j);
 		b = i;
 	}
 }
 
+
 public class SupSubRef {
 
 	public static void main(String[] args) {
-		
+
 		X x = new X(10);
 		X x2;
 		Y y = new Y(5, 6);
-		
+
 		x2 = x; // OK, both of same type.
 		System.out.println("X2.a: " + x2.a);
 		System.out.println("x.a: " + x.a);
-		
-		x2 = y;  // still ok because Y is derived from X.
+
+		x2 = y; // still ok because Y is derived from X.
 		System.out.println("X2.a: " + x2.a);
-		
+
 		// X references know only about X members
-		x2.a = 19;  // OK
+		x2.a = 19; // OK
 // 		x2.b = 27;  // Error, X does not have a b member. 
 
-		
 	}
 
 }

From 9983e266ba3beb85c7d7aae5eed231ad913aad7d Mon Sep 17 00:00:00 2001
From: Ceiling_roof <48134466+ResilientSpring@users.noreply.github.com>
Date: Tue, 3 Oct 2023 20:08:53 +0800
Subject: [PATCH 16/38] Committed on or around 2023/10/03

---
 Chapter8/Try_This_8_1.java | 19 +++++++++++++++++++
 1 file changed, 19 insertions(+)
 create mode 100644 Chapter8/Try_This_8_1.java

diff --git a/Chapter8/Try_This_8_1.java b/Chapter8/Try_This_8_1.java
new file mode 100644
index 0000000..a331471
--- /dev/null
+++ b/Chapter8/Try_This_8_1.java
@@ -0,0 +1,19 @@
+// A character queue interface
+interface ICharQ{
+	
+	// Put a character into the queue.
+	void put(char ch);
+	
+	// Get a character from the queue.
+	char get();
+}
+
+
+public class Try_This_8_1 {
+
+	public static void main(String[] args) {
+		// TODO Auto-generated method stub
+
+	}
+
+}

From d972d3051068a94e30da086eb97b48d97920bed2 Mon Sep 17 00:00:00 2001
From: Ceiling_roof <48134466+ResilientSpring@users.noreply.github.com>
Date: Tue, 3 Oct 2023 20:17:09 +0800
Subject: [PATCH 17/38] Committed on or around 2023/10/03

---
 Chapter8/Try_This_8_1.java | 21 +++++++++++++++++++++
 1 file changed, 21 insertions(+)

diff --git a/Chapter8/Try_This_8_1.java b/Chapter8/Try_This_8_1.java
index a331471..ed4e8dd 100644
--- a/Chapter8/Try_This_8_1.java
+++ b/Chapter8/Try_This_8_1.java
@@ -9,6 +9,27 @@ interface ICharQ{
 }
 
 
+// A fixed-size queue class for characters.
+class FixedQueue implements ICharQ{
+	
+	private char q[];  // This array holds the queue. 
+	private int putloc, getloc; // The put and get indices.
+
+	@Override
+	public void put(char ch) {
+		// TODO Auto-generated method stub
+		
+	}
+
+	@Override
+	public char get() {
+		// TODO Auto-generated method stub
+		return 0;
+	}
+	
+}
+
+
 public class Try_This_8_1 {
 
 	public static void main(String[] args) {

From 3944846104635066af3e6702f2ed8f34527cef16 Mon Sep 17 00:00:00 2001
From: Ceiling_roof <48134466+ResilientSpring@users.noreply.github.com>
Date: Tue, 3 Oct 2023 20:19:44 +0800
Subject: [PATCH 18/38] Committed on or around 2023/10/03

---
 Chapter8/Try_This_8_1.java | 8 +++++---
 1 file changed, 5 insertions(+), 3 deletions(-)

diff --git a/Chapter8/Try_This_8_1.java b/Chapter8/Try_This_8_1.java
index ed4e8dd..e227098 100644
--- a/Chapter8/Try_This_8_1.java
+++ b/Chapter8/Try_This_8_1.java
@@ -14,14 +14,16 @@ class FixedQueue implements ICharQ{
 	
 	private char q[];  // This array holds the queue. 
 	private int putloc, getloc; // The put and get indices.
+	
+	public FixedQueue(int size) {
+		q = new char[size];  // allocate memory for queue.
+		putloc = getloc = 0;
+	}
 
-	@Override
 	public void put(char ch) {
-		// TODO Auto-generated method stub
 		
 	}
 
-	@Override
 	public char get() {
 		// TODO Auto-generated method stub
 		return 0;

From 77dd325e75ad5f8184623abdc9ffc6f42822484f Mon Sep 17 00:00:00 2001
From: Ceiling_roof <48134466+ResilientSpring@users.noreply.github.com>
Date: Tue, 3 Oct 2023 20:24:25 +0800
Subject: [PATCH 19/38] Committed on or around 2023/10/03

---
 Chapter8/Try_This_8_1.java | 5 +++++
 1 file changed, 5 insertions(+)

diff --git a/Chapter8/Try_This_8_1.java b/Chapter8/Try_This_8_1.java
index e227098..24d0937 100644
--- a/Chapter8/Try_This_8_1.java
+++ b/Chapter8/Try_This_8_1.java
@@ -21,7 +21,12 @@ public FixedQueue(int size) {
 	}
 
 	public void put(char ch) {
+		if(putloc == q.length) {
+			System.out.println(" - Queue is full.");
+			return;
+		}
 		
+		q[putloc++] = ch;
 	}
 
 	public char get() {

From 62ee7e47c5c803109379fe192c12048ec1cf9cda Mon Sep 17 00:00:00 2001
From: Ceiling_roof <48134466+ResilientSpring@users.noreply.github.com>
Date: Tue, 3 Oct 2023 20:26:25 +0800
Subject: [PATCH 20/38] Committed on or around 2023/10/03

---
 Chapter8/Try_This_8_1.java | 9 +++++++--
 1 file changed, 7 insertions(+), 2 deletions(-)

diff --git a/Chapter8/Try_This_8_1.java b/Chapter8/Try_This_8_1.java
index 24d0937..d35cea1 100644
--- a/Chapter8/Try_This_8_1.java
+++ b/Chapter8/Try_This_8_1.java
@@ -30,8 +30,13 @@ public void put(char ch) {
 	}
 
 	public char get() {
-		// TODO Auto-generated method stub
-		return 0;
+		
+		if (getloc == putloc) {
+			System.out.println(" - Queue is empty.");
+			
+			return (char) 0;
+		}
+		return q[getloc++];
 	}
 	
 }

From fdb7b1ee837ea9e329862309e5575ffbcf624d27 Mon Sep 17 00:00:00 2001
From: Ceiling_roof <48134466+ResilientSpring@users.noreply.github.com>
Date: Tue, 3 Oct 2023 20:30:12 +0800
Subject: [PATCH 21/38] Committed on or around 2023/10/03

---
 Chapter8/Try_This_8_1.java | 15 +++++++++++++++
 1 file changed, 15 insertions(+)

diff --git a/Chapter8/Try_This_8_1.java b/Chapter8/Try_This_8_1.java
index d35cea1..09c1c42 100644
--- a/Chapter8/Try_This_8_1.java
+++ b/Chapter8/Try_This_8_1.java
@@ -41,6 +41,21 @@ public char get() {
 	
 }
 
+class CircularQueue implements ICharQ{
+	private char q[];  // this array holds the queue.
+	private int putloc, getloc;  // the put and get indices.
+
+	public void put(char ch) {
+		// TODO Auto-generated method stub
+		
+	}
+
+	public char get() {
+		// TODO Auto-generated method stub
+		return 0;
+	}
+}
+
 
 public class Try_This_8_1 {
 

From c6118f9e52c7b5064a0077be61cd36ba0d7644a5 Mon Sep 17 00:00:00 2001
From: Ceiling_roof <48134466+ResilientSpring@users.noreply.github.com>
Date: Tue, 3 Oct 2023 20:46:52 +0800
Subject: [PATCH 22/38] Committed on or around 2023/10/03

---
 Chapter8/Try_This_8_1.java | 41 ++++++++++++++++++++++++++++++++++++--
 1 file changed, 39 insertions(+), 2 deletions(-)

diff --git a/Chapter8/Try_This_8_1.java b/Chapter8/Try_This_8_1.java
index 09c1c42..4f11bee 100644
--- a/Chapter8/Try_This_8_1.java
+++ b/Chapter8/Try_This_8_1.java
@@ -44,19 +44,56 @@ public char get() {
 class CircularQueue implements ICharQ{
 	private char q[];  // this array holds the queue.
 	private int putloc, getloc;  // the put and get indices.
+	
+	// Construct an empty queue given its size.
+	public CircularQueue(int size) {
+		q = new char[size + 1];  // allocate memory for queue
+		putloc = getloc = 0;
+	}
 
 	public void put(char ch) {
-		// TODO Auto-generated method stub
+		/*
+		 * Queue is full if either putloc is one less than getloc, 
+		 * or if putloc is at the end of the array and getloc is at 
+		 * the beginning.
+		 * */
+		
+		if (putloc + 1 == getloc | ((putloc == q.length - 1) & (getloc == 0))) {
+			System.out.println(" - Queue is full. ");
+			return;
+		}
+		
+		q[putloc++] = ch;
+		
+		if (putloc == q.length) {
+			putloc = 0;
+		}
 		
 	}
 
 	public char get() {
 		// TODO Auto-generated method stub
-		return 0;
+		if (getloc == putloc) {
+			System.out.println(" - Queue is empty.");
+			return (char) 0;
+		}
+		
+		char ch = q[getloc++];
+		
+		if (getloc == q.length) {
+			getloc = 0;
+		}
+		
+		return ch;
 	}
 }
 
 
+class DynQueue implements ICharQ{
+	
+}
+
+
 public class Try_This_8_1 {
 
 	public static void main(String[] args) {

From 4b36e2baae369bc31a3930fc5e8f53c592d14ba7 Mon Sep 17 00:00:00 2001
From: Ceiling_roof <48134466+ResilientSpring@users.noreply.github.com>
Date: Tue, 3 Oct 2023 20:47:06 +0800
Subject: [PATCH 23/38] Committed on or around 2023/10/03

---
 Chapter8/Try_This_8_1.java | 12 ++++++++++++
 1 file changed, 12 insertions(+)

diff --git a/Chapter8/Try_This_8_1.java b/Chapter8/Try_This_8_1.java
index 4f11bee..45afa8b 100644
--- a/Chapter8/Try_This_8_1.java
+++ b/Chapter8/Try_This_8_1.java
@@ -90,6 +90,18 @@ public char get() {
 
 
 class DynQueue implements ICharQ{
+
+	@Override
+	public void put(char ch) {
+		// TODO Auto-generated method stub
+		
+	}
+
+	@Override
+	public char get() {
+		// TODO Auto-generated method stub
+		return 0;
+	}
 	
 }
 

From b1f34621768464fed08fd6fc929ee306d6ecdb51 Mon Sep 17 00:00:00 2001
From: Ceiling_roof <48134466+ResilientSpring@users.noreply.github.com>
Date: Tue, 3 Oct 2023 20:53:53 +0800
Subject: [PATCH 24/38] Committed on or around 2023/10/03

---
 Chapter8/Try_This_8_1.java | 39 ++++++++++++++++++++++++++++++++++----
 1 file changed, 35 insertions(+), 4 deletions(-)

diff --git a/Chapter8/Try_This_8_1.java b/Chapter8/Try_This_8_1.java
index 45afa8b..892c1de 100644
--- a/Chapter8/Try_This_8_1.java
+++ b/Chapter8/Try_This_8_1.java
@@ -1,4 +1,7 @@
 // A character queue interface
+
+import javax.print.attribute.Size2DSyntax;
+
 interface ICharQ{
 	
 	// Put a character into the queue.
@@ -90,17 +93,45 @@ public char get() {
 
 
 class DynQueue implements ICharQ{
+	
+	private char q[];
+	private int putloc, getloc;
+	
+	public DynQueue(int size) {
+		q = new char[size];
+		putloc = getloc = 0;
+	}
+
 
-	@Override
 	public void put(char ch) {
 		// TODO Auto-generated method stub
 		
+		if (putloc == q.length) {
+			// increase queue size
+			char t[] = new char[q.length * 2];
+			
+			// copy elements into new queue
+			for (int i = 0; i < q.length; i++) {
+
+				t[i] = q[i];
+				
+				q = t;
+			}
+			q[putloc++] = ch;
+		}
+		
 	}
 
-	@Override
+
 	public char get() {
-		// TODO Auto-generated method stub
-		return 0;
+		
+		if (getloc == putloc) {
+			System.out.println(" - Queue is empty.");
+			return (char) 0;
+		} 
+		
+		return q[getloc++];
+		
 	}
 	
 }

From f1396e2068ed929249321fdd1a013e5c204de83b Mon Sep 17 00:00:00 2001
From: Ceiling_roof <48134466+ResilientSpring@users.noreply.github.com>
Date: Tue, 3 Oct 2023 20:56:52 +0800
Subject: [PATCH 25/38] Committed on or around 2023/10/03

---
 Chapter8/Try_This_8_1.java | 8 ++++++--
 1 file changed, 6 insertions(+), 2 deletions(-)

diff --git a/Chapter8/Try_This_8_1.java b/Chapter8/Try_This_8_1.java
index 892c1de..0678a7f 100644
--- a/Chapter8/Try_This_8_1.java
+++ b/Chapter8/Try_This_8_1.java
@@ -1,7 +1,5 @@
 // A character queue interface
 
-import javax.print.attribute.Size2DSyntax;
-
 interface ICharQ{
 	
 	// Put a character into the queue.
@@ -141,6 +139,12 @@ public class Try_This_8_1 {
 
 	public static void main(String[] args) {
 		// TODO Auto-generated method stub
+		
+		FixedQueue q1 = new FixedQueue(10);
+		DynQueue q2 = new DynQueue(5);
+		CircularQueue q3 = new CircularQueue(10);
+		
+		ICharQ iQ;
 
 	}
 

From 5210b57c104bc2af28009e9f1303211c41bd0683 Mon Sep 17 00:00:00 2001
From: Ceiling_roof <48134466+ResilientSpring@users.noreply.github.com>
Date: Tue, 3 Oct 2023 20:57:24 +0800
Subject: [PATCH 26/38] Committed on or around 2023/10/03

---
 Chapter8/Try_This_8_1.java | 3 +++
 1 file changed, 3 insertions(+)

diff --git a/Chapter8/Try_This_8_1.java b/Chapter8/Try_This_8_1.java
index 0678a7f..25c054c 100644
--- a/Chapter8/Try_This_8_1.java
+++ b/Chapter8/Try_This_8_1.java
@@ -145,6 +145,9 @@ public static void main(String[] args) {
 		CircularQueue q3 = new CircularQueue(10);
 		
 		ICharQ iQ;
+		
+		char ch; 
+		int i;
 
 	}
 

From 85615cdb43221ed9b56553873ef8bec415b44fa5 Mon Sep 17 00:00:00 2001
From: Ceiling_roof <48134466+ResilientSpring@users.noreply.github.com>
Date: Tue, 3 Oct 2023 21:22:06 +0800
Subject: [PATCH 27/38] Committed on or around 2023/10/03

---
 Chapter8/Try_This_8_1.java | 9 +++++++++
 1 file changed, 9 insertions(+)

diff --git a/Chapter8/Try_This_8_1.java b/Chapter8/Try_This_8_1.java
index 25c054c..de4b1dc 100644
--- a/Chapter8/Try_This_8_1.java
+++ b/Chapter8/Try_This_8_1.java
@@ -148,6 +148,15 @@ public static void main(String[] args) {
 		
 		char ch; 
 		int i;
+		
+		iQ = q1;
+		
+		// Put some characters into fixed queue.
+		for (i = 0; i < 10; i++) {
+			iQ.put((char) ('A' + i));
+		}
+		
+		// Show the queue.
 
 	}
 

From 935042f1502e4cdd298995956f2c8af015bcd59a Mon Sep 17 00:00:00 2001
From: Ceiling_roof <48134466+ResilientSpring@users.noreply.github.com>
Date: Tue, 3 Oct 2023 23:58:01 +0800
Subject: [PATCH 28/38] Committed on or around 2023/10/03

---
 Chapter8/Try_This_8_1.java | 1 +
 1 file changed, 1 insertion(+)

diff --git a/Chapter8/Try_This_8_1.java b/Chapter8/Try_This_8_1.java
index de4b1dc..07350db 100644
--- a/Chapter8/Try_This_8_1.java
+++ b/Chapter8/Try_This_8_1.java
@@ -157,6 +157,7 @@ public static void main(String[] args) {
 		}
 		
 		// Show the queue.
+		System.out.print("Contents of fixed queue: ");
 
 	}
 

From 421badb760c9bdd0d8b62429277d7835283b1d6e Mon Sep 17 00:00:00 2001
From: Ceiling_roof <48134466+ResilientSpring@users.noreply.github.com>
Date: Wed, 4 Oct 2023 00:00:02 +0800
Subject: [PATCH 29/38] Committed on or around 2023/10/03

---
 Chapter8/Try_This_8_1.java | 5 +++++
 1 file changed, 5 insertions(+)

diff --git a/Chapter8/Try_This_8_1.java b/Chapter8/Try_This_8_1.java
index 07350db..7fc33f2 100644
--- a/Chapter8/Try_This_8_1.java
+++ b/Chapter8/Try_This_8_1.java
@@ -158,6 +158,11 @@ public static void main(String[] args) {
 		
 		// Show the queue.
 		System.out.print("Contents of fixed queue: ");
+		
+		for (i = 0; i < 10; i++) {
+			ch = iQ.get();
+			System.out.print(ch);
+		}
 
 	}
 

From d4331dc3f18d9bcc1c4197c8d5ffc71c0dadf175 Mon Sep 17 00:00:00 2001
From: Ceiling_roof <48134466+ResilientSpring@users.noreply.github.com>
Date: Wed, 4 Oct 2023 00:02:31 +0800
Subject: [PATCH 30/38] Committed on or around 2023/10/04

---
 Chapter8/Try_This_8_1.java | 7 +++++++
 1 file changed, 7 insertions(+)

diff --git a/Chapter8/Try_This_8_1.java b/Chapter8/Try_This_8_1.java
index 7fc33f2..f5af1c9 100644
--- a/Chapter8/Try_This_8_1.java
+++ b/Chapter8/Try_This_8_1.java
@@ -163,6 +163,13 @@ public static void main(String[] args) {
 			ch = iQ.get();
 			System.out.print(ch);
 		}
+		
+		System.out.println();
+		
+		iQ = q3;
+		
+		// Put some characters into circular queue.
+		
 
 	}
 

From 547a382f210161b79c4bea716e77916f5b697ed2 Mon Sep 17 00:00:00 2001
From: Ceiling_roof <48134466+ResilientSpring@users.noreply.github.com>
Date: Wed, 4 Oct 2023 00:10:56 +0800
Subject: [PATCH 31/38] Committed on or around 2023/10/04

---
 Chapter8/Try_This_8_1.java | 21 +++++++++++++++++++++
 1 file changed, 21 insertions(+)

diff --git a/Chapter8/Try_This_8_1.java b/Chapter8/Try_This_8_1.java
index f5af1c9..b5864d5 100644
--- a/Chapter8/Try_This_8_1.java
+++ b/Chapter8/Try_This_8_1.java
@@ -164,12 +164,33 @@ public static void main(String[] args) {
 			System.out.print(ch);
 		}
 		
+		System.out.println();
+		
+		iQ = q2;
+		
+		// Put some characters into dynamic queue.
+		for (i = 0; i < 10; i++) {
+			iQ.put((char) ('Z' - i));
+		}
+		
+		// Show the queue.
+		System.out.print("Contents of dynamic queue: ");
+		
+		
 		System.out.println();
 		
 		iQ = q3;
 		
 		// Put some characters into circular queue.
+		for (i = 0; i < 20; i++) {
+			iQ.put((char) ('A' + i));
+		}
 		
+		// Show the queue.
+		System.out.print("Contents of circular queue: ");
+		for (i = 0; i < 10; i++) {
+			
+		}
 
 	}
 

From a80ed15e9e362320b3d506c7e40960a43441aa7e Mon Sep 17 00:00:00 2001
From: Ceiling_roof <48134466+ResilientSpring@users.noreply.github.com>
Date: Wed, 4 Oct 2023 00:13:44 +0800
Subject: [PATCH 32/38] Committed on or around 2023/10/04

---
 Chapter8/Try_This_8_1.java | 4 ++++
 1 file changed, 4 insertions(+)

diff --git a/Chapter8/Try_This_8_1.java b/Chapter8/Try_This_8_1.java
index b5864d5..3528fe2 100644
--- a/Chapter8/Try_This_8_1.java
+++ b/Chapter8/Try_This_8_1.java
@@ -175,6 +175,10 @@ public static void main(String[] args) {
 		
 		// Show the queue.
 		System.out.print("Contents of dynamic queue: ");
+		for (i = 0; i < 10; i++) {
+			ch = iQ.get();
+			System.out.print(ch);
+		}
 		
 		
 		System.out.println();

From e3e15dc2973ba99e7865057fad34fb56201d6bdf Mon Sep 17 00:00:00 2001
From: Ceiling_roof <48134466+ResilientSpring@users.noreply.github.com>
Date: Wed, 4 Oct 2023 12:08:31 +0800
Subject: [PATCH 33/38] Committed on or around 2023/10/04

---
 Chapter8/Try_This_8_1.java | 30 +++++++++++++++++++++++++++---
 1 file changed, 27 insertions(+), 3 deletions(-)

diff --git a/Chapter8/Try_This_8_1.java b/Chapter8/Try_This_8_1.java
index 3528fe2..735ce48 100644
--- a/Chapter8/Try_This_8_1.java
+++ b/Chapter8/Try_This_8_1.java
@@ -18,7 +18,8 @@ class FixedQueue implements ICharQ{
 	
 	public FixedQueue(int size) {
 		q = new char[size];  // allocate memory for queue.
-		putloc = getloc = 0;
+
+putloc = getloc = 0;
 	}
 
 	public void put(char ch) {
@@ -180,7 +181,6 @@ public static void main(String[] args) {
 			System.out.print(ch);
 		}
 		
-		
 		System.out.println();
 		
 		iQ = q3;
@@ -193,7 +193,31 @@ public static void main(String[] args) {
 		// Show the queue.
 		System.out.print("Contents of circular queue: ");
 		for (i = 0; i < 10; i++) {
-			
+			ch = iQ.get();
+			System.out.print(ch);
+		}
+		
+		System.out.println();
+		
+		// Put more characters into circular queue.
+		for (i = 0; i < 20; i++) {
+			iQ.put((char) ('A' + i));
+		}
+		
+		// Show the queue.
+		System.out.print("Contents of circular queue: ");
+		for (i = 0; i < 10; i++) {			
+			ch = iQ.get();
+			System.out.print(ch);
+		}
+		
+		System.out.println("\nStore and consume from" + " circular queue.");
+		
+		// Store in and consume from circular queue.
+		for (i = 0; i < 20; i++) {
+			iQ.put((char) ('A' + i));
+			ch = iQ.get();
+			System.out.print(ch);
 		}
 
 	}

From 30e0870af28223fa624de4e8e7b6aa1953c744b9 Mon Sep 17 00:00:00 2001
From: Ceiling_roof <48134466+ResilientSpring@users.noreply.github.com>
Date: Wed, 4 Oct 2023 12:30:24 +0800
Subject: [PATCH 34/38] Committed on or around 2023/10/04

---
 Chapter8/Try_This_8_1.java | 6 +++---
 1 file changed, 3 insertions(+), 3 deletions(-)

diff --git a/Chapter8/Try_This_8_1.java b/Chapter8/Try_This_8_1.java
index 735ce48..b3194e5 100644
--- a/Chapter8/Try_This_8_1.java
+++ b/Chapter8/Try_This_8_1.java
@@ -113,12 +113,12 @@ public void put(char ch) {
 			for (int i = 0; i < q.length; i++) {
 
 				t[i] = q[i];
-				
-				q = t;
 			}
-			q[putloc++] = ch;
+			
+			q = t;
 		}
 		
+		q[putloc++] = ch;
 	}
 
 

From 14325f9bcfaa3f113bb40e5647b215a4c281ef66 Mon Sep 17 00:00:00 2001
From: Ceiling_roof <48134466+ResilientSpring@users.noreply.github.com>
Date: Wed, 4 Oct 2023 13:02:19 +0800
Subject: [PATCH 35/38] Committed on or around 2023/10/04

---
 Chapter8/Try_This_8_1.java | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/Chapter8/Try_This_8_1.java b/Chapter8/Try_This_8_1.java
index b3194e5..a892e59 100644
--- a/Chapter8/Try_This_8_1.java
+++ b/Chapter8/Try_This_8_1.java
@@ -19,7 +19,7 @@ class FixedQueue implements ICharQ{
 	public FixedQueue(int size) {
 		q = new char[size];  // allocate memory for queue.
 
-putloc = getloc = 0;
+		putloc = getloc = 0;
 	}
 
 	public void put(char ch) {

From 1165d4bdd74eb652a72ae037fee612c4e79b1ae1 Mon Sep 17 00:00:00 2001
From: Ceiling_roof <48134466+ResilientSpring@users.noreply.github.com>
Date: Wed, 4 Oct 2023 13:15:01 +0800
Subject: [PATCH 36/38] Committed on or around 2023/10/04

---
 Chapter8/Try_This_8_1.java | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/Chapter8/Try_This_8_1.java b/Chapter8/Try_This_8_1.java
index a892e59..542eb47 100644
--- a/Chapter8/Try_This_8_1.java
+++ b/Chapter8/Try_This_8_1.java
@@ -186,7 +186,7 @@ public static void main(String[] args) {
 		iQ = q3;
 		
 		// Put some characters into circular queue.
-		for (i = 0; i < 20; i++) {
+		for (i = 0; i < 10; i++) {
 			iQ.put((char) ('A' + i));
 		}
 		
@@ -200,7 +200,7 @@ public static void main(String[] args) {
 		System.out.println();
 		
 		// Put more characters into circular queue.
-		for (i = 0; i < 20; i++) {
+		for (i = 10; i < 20; i++) {
 			iQ.put((char) ('A' + i));
 		}
 		

From cc0f63f4c15dbe5ed2a8bb7410c7623a017bfa7c Mon Sep 17 00:00:00 2001
From: Ceiling_roof <48134466+ResilientSpring@users.noreply.github.com>
Date: Wed, 4 Oct 2023 14:02:22 +0800
Subject: [PATCH 37/38] Committed on or around 2023/10/04

---
 .../Interface/Interfaces_Can_Be_Extended.java  | 18 ++++++++++++++++++
 1 file changed, 18 insertions(+)
 create mode 100644 Chapter8/Interface/Interfaces_Can_Be_Extended.java

diff --git a/Chapter8/Interface/Interfaces_Can_Be_Extended.java b/Chapter8/Interface/Interfaces_Can_Be_Extended.java
new file mode 100644
index 0000000..c101761
--- /dev/null
+++ b/Chapter8/Interface/Interfaces_Can_Be_Extended.java
@@ -0,0 +1,18 @@
+package Interface;
+
+interface A{
+	
+	void meth1();
+	void meth2();
+}
+
+
+
+public class Interfaces_Can_Be_Extended {
+
+	public static void main(String[] args) {
+		// TODO Auto-generated method stub
+
+	}
+
+}

From fdd7c3de3831b4b30a87b1ef9f3ef5dcbbde3c05 Mon Sep 17 00:00:00 2001
From: Ceiling_roof <48134466+ResilientSpring@users.noreply.github.com>
Date: Wed, 4 Oct 2023 14:12:36 +0800
Subject: [PATCH 38/38] Committed on or around 2023/10/04

---
 .../Interface/Interfaces_Can_Be_Extended.java | 33 +++++++++++++++++++
 1 file changed, 33 insertions(+)

diff --git a/Chapter8/Interface/Interfaces_Can_Be_Extended.java b/Chapter8/Interface/Interfaces_Can_Be_Extended.java
index c101761..69c49e7 100644
--- a/Chapter8/Interface/Interfaces_Can_Be_Extended.java
+++ b/Chapter8/Interface/Interfaces_Can_Be_Extended.java
@@ -1,17 +1,50 @@
 package Interface;
 
+// One interface can extend another.
 interface A{
 	
 	void meth1();
 	void meth2();
 }
 
+// B now includes meth1() and meth2() - it adds meth3().
+interface B extends A{  // B inherits A.
+	void meth3();
+}
+
+// This class must implement all of A and B
+class MyClass implements B{
+
+	@Override
+	public void meth1() {
+		// TODO Auto-generated method stub
+		System.out.println("Implement meth1(). ");
+	}
+
+	@Override
+	public void meth2() {
+		// TODO Auto-generated method stub
+		System.out.println("Implement meth2(). ");
+	}
+
+	@Override
+	public void meth3() {
+		// TODO Auto-generated method stub
+		System.out.println("Implement meth3(). ");
+	}
+}
 
 
 public class Interfaces_Can_Be_Extended {
 
 	public static void main(String[] args) {
 		// TODO Auto-generated method stub
+		
+		MyClass obMyClass = new MyClass();
+		
+		obMyClass.meth1();
+		obMyClass.meth2();
+		obMyClass.meth3();
 
 	}