From: gumartinm <gustavo@gumartinm.name>
Date: Wed, 2 May 2012 16:13:49 +0000 (+0200)
Subject: Examples: try/catch/finally blocks and exceptions.
X-Git-Url: https://git.gumartinm.name/?a=commitdiff_plain;h=4b498d08c86ebdaa53df941b29fcb1498ddf4973;p=JavaForFun

Examples: try/catch/finally blocks and exceptions.
---

diff --git a/Allgemeines/TryCatchFinally/src/de/example/tryfinally/Main.java b/Allgemeines/TryCatchFinally/src/de/example/tryfinally/Main.java
new file mode 100644
index 0000000..49fad84
--- /dev/null
+++ b/Allgemeines/TryCatchFinally/src/de/example/tryfinally/Main.java
@@ -0,0 +1,80 @@
+package de.example.tryfinally;
+
+public class Main {
+	static String result;
+	
+	public static void main(String[] args) {
+		System.out.println("Calling go");
+        String st = returnAndFinally();
+        System.out.println("Back from go: " + st);
+        System.out.println("Surprise!! " + result);
+        
+        try {
+        	System.out.println(noCatchAndFinally());
+		} catch (Exception e) {
+			System.out.println("Second catch.");
+			e.printStackTrace();
+		}
+	}
+
+    public static String returnAndFinally() {
+    	result = "NOK";
+    	
+        try {
+            messingAround();
+            return result;
+        }
+        catch (Exception ex) {
+            System.out.println("Entered catch: " + result);
+            result = "OK";
+            //This is the return statement that this method will execute in case of any Exception class or subclass is thrown.
+            return result;
+        }
+        finally {
+        	//You will not see FINALLY in the "Back from go:" statement.
+        	//From stackoverflow: 
+        	//http://stackoverflow.com/questions/421797/what-really-happens-in-a-try-return-x-finally-x-null-statement.
+        	// * Code before return statement is executed
+        	// * Expression in return statement is evaluated
+        	// * finally block is executed
+        	// * Result evaluated in step 2 is returned
+
+        	result = "FINALLY";
+            System.out.println("Entered finally: " + result);
+            //NEVER USE return in finally block because you can loose the stack if some exception is thrown from the try block!!! 
+            //You finish with this return instead of the previous one.
+            //http://stackoverflow.com/questions/48088/returning-from-a-finally-block-in-java
+            //return result;
+        }
+    }
+    
+    public static void messingAround() throws Exception {
+    	throw(new Exception());
+    }
+    
+    
+    public static String noCatchAndFinally() throws Exception {
+    	try {
+    		messingAround();
+    		return "You will not see me";
+    	}
+    	finally {
+    		try 
+    		{
+    			//Catching this exception does not swallow the previous one (if there was one)
+    			messingAroundReturns();
+    		}
+    		catch (Exception e) {
+    			System.out.println("First catch.");
+    			e.printStackTrace();
+    		}
+    		//NEVER USE return in finally block because you can loose the stack if some exception is thrown from the try block!!! 
+            //http://stackoverflow.com/questions/48088/returning-from-a-finally-block-in-java
+            return "Do not do this. You are loosing the exception thrown by messingAround method!!!";
+    	}
+    }
+    
+    public static void messingAroundReturns() throws Exception {
+    	throw(new Exception());
+    }
+}