From 8577edd5e7d435d3121af48b21867c2d2529f94a Mon Sep 17 00:00:00 2001
From: Selebrator <l.panneke@googlemail.com>
Date: Thu, 13 Jun 2019 23:49:57 +0200
Subject: [PATCH] =?UTF-8?q?Ein=20paar=20alternative=20L=C3=B6sungen=20f?=
 =?UTF-8?q?=C3=BCr=2010.4?=
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---
 src/main/java/_10/_4/lukas/NameOutput.java    | 14 +++++++
 .../_10/_4/lukas/NameOutputBusyWaiting.java   | 31 ++++++++++++++++
 .../java/_10/_4/lukas/NameOutputFairLock.java | 22 +++++++++++
 .../_10/_4/lukas/NameOutputWaitNotify.java    | 37 +++++++++++++++++++
 4 files changed, 104 insertions(+)
 create mode 100644 src/main/java/_10/_4/lukas/NameOutput.java
 create mode 100644 src/main/java/_10/_4/lukas/NameOutputBusyWaiting.java
 create mode 100644 src/main/java/_10/_4/lukas/NameOutputFairLock.java
 create mode 100644 src/main/java/_10/_4/lukas/NameOutputWaitNotify.java

diff --git a/src/main/java/_10/_4/lukas/NameOutput.java b/src/main/java/_10/_4/lukas/NameOutput.java
new file mode 100644
index 0000000..0d56e87
--- /dev/null
+++ b/src/main/java/_10/_4/lukas/NameOutput.java
@@ -0,0 +1,14 @@
+package _10._4.lukas;
+
+public abstract class NameOutput {
+
+	private NameOutput() {
+	}
+
+	public static void main(String[] args) {
+		final int n = 3;
+		for(int i = 0; i < n; i++) {
+			new NameOutputFairLock().start();
+		}
+	}
+}
diff --git a/src/main/java/_10/_4/lukas/NameOutputBusyWaiting.java b/src/main/java/_10/_4/lukas/NameOutputBusyWaiting.java
new file mode 100644
index 0000000..eead11f
--- /dev/null
+++ b/src/main/java/_10/_4/lukas/NameOutputBusyWaiting.java
@@ -0,0 +1,31 @@
+package _10._4.lukas;
+
+// ordered by creation time, deadlocks if any thread in the chain is interrupted.
+public class NameOutputBusyWaiting extends Thread {
+
+	private static final Object LOCK = new Object();
+
+	private static int counter = 0;
+	private static int total = 0;
+
+	private final int number;
+
+	public NameOutputBusyWaiting() {
+		synchronized(LOCK) {
+			this.number = total;
+			total++;
+		}
+	}
+
+	@Override
+	public void run() {
+		while(!this.isInterrupted()) {
+			synchronized(LOCK) {
+				if(this.number == counter) {
+					System.out.println(this.getName());
+					counter = (counter + 1) % total;
+				}
+			}
+		}
+	}
+}
diff --git a/src/main/java/_10/_4/lukas/NameOutputFairLock.java b/src/main/java/_10/_4/lukas/NameOutputFairLock.java
new file mode 100644
index 0000000..d7e6ccf
--- /dev/null
+++ b/src/main/java/_10/_4/lukas/NameOutputFairLock.java
@@ -0,0 +1,22 @@
+package _10._4.lukas;
+
+import java.util.concurrent.locks.Lock;
+import java.util.concurrent.locks.ReentrantLock;
+
+// ordered by least recent access since creation
+public class NameOutputFairLock extends Thread {
+
+	private static final Lock LOCK = new ReentrantLock(true);
+
+	@Override
+	public void run() {
+		while(!this.isInterrupted()) {
+			LOCK.lock();
+			try {
+				System.out.println(this.getName());
+			} finally {
+				LOCK.unlock();
+			}
+		}
+	}
+}
diff --git a/src/main/java/_10/_4/lukas/NameOutputWaitNotify.java b/src/main/java/_10/_4/lukas/NameOutputWaitNotify.java
new file mode 100644
index 0000000..bccc503
--- /dev/null
+++ b/src/main/java/_10/_4/lukas/NameOutputWaitNotify.java
@@ -0,0 +1,37 @@
+package _10._4.lukas;
+
+// ordered by creation time, deadlocks if any thread in the chain is interrupted.
+public class NameOutputWaitNotify extends Thread {
+
+	private static final Object LOCK = new Object();
+
+	private static int counter = 0;
+	private static int total = 0;
+
+	private final int number;
+
+	public NameOutputWaitNotify() {
+		synchronized(LOCK) {
+			this.number = total;
+			total++;
+		}
+	}
+
+	@Override
+	public void run() {
+		while(!this.isInterrupted()) {
+			synchronized(LOCK) {
+				while(this.number != counter) {
+					try {
+						LOCK.wait();
+					} catch(InterruptedException e) {
+						System.out.println(this.getName() + " was interrupted");
+					}
+				}
+				System.out.println(this.getName());
+				counter = (counter + 1) % total;
+				LOCK.notifyAll();
+			}
+		}
+	}
+}