Difference between Stack Overflow error and Out of memory error in android?
When you start JVM you define how much RAM it can use use for processing. JVM divides this into certain memory locations for its processing purpose, two of those are Stack & Heap.
Out of memory error is related to Heap. If you have large objects (or) referenced objects in memory, then you will see Out of memory error . If you have strong references to objects, then GC can't clean the memory space allocated for that object. When JVM tries to allocate memory for new object and not enough space available it throws Out of memory error because it can't allocate required amount of memory.
How to avoid: Make sure unnecessary objects are available for GC.
Stack Overflow error is related to stack. All your local variables and methods calls related data will be on stack. For every method call one stack frame will be created and local as well as method call related data will be placed inside the stack frame. Once method execution is completed, stack frame will be removed. ONE WAY to reproduce this is, have infinite loop for method call, you will see Stack Overflow error, because stack frame will be populated with method data for every call but it won't be freed (removed).
How to avoid: Make sure method calls are ending (not in infinite loop).
Here are few differences between stack and heap memory in Java:
1) Main difference between heap and stack is that stack memory is used to store local variables and function call, while heap memory is used to store objects in Java. No matter, where object is created in code e.g. as member variable, local variable or class variable, they are always created inside heap space in Java.
2) Each Thread in Java has there own stack which can be specified using -Xss JVM parameter, similarly you can also specify heap size of Java program using JVM option -Xms and -Xmx where -Xms is starting size of heap and -Xmx is maximum size of java heap.
3) If there is no memory left in stack for storing function call or local variable, JVM will throw java.lang.StackOverFlowError, while if there is no more heap space for creating object, JVM will throw java.lang.OutOfMemoryError: Java Heap Space.
4) If you are using Recursion on which method calls itself, You can quickly fill up stack memory. Another difference between stack and heap is that size of stack memory is lot lesser than size of heap memory in Java.
5) Variables stored in stacks are only visible to the owner Thread, while objects created in heap are visible to all thread. In other words stack memory is kind of private memory of Java Threads, while heap memory is shared among all threads.
Difference between debug.apk and release.apk android ?
The difference between debug and release builds is for example, that you can get the log output from the debug build but not from the release build.
Debug builds can be signed with the default keystore, the release builds have to be signed with your created keystore.
The Android build process signs your application differently depending on which build mode you use to build your application.
There are two build modes: debug mode and release mode.
You use debug mode when you are developing and testing your application.
You use release mode when you want to build a release version of your application that you can distribute directly to users or publish on an application marketplace such as Google Play.
When you build in debug mode the Android SDK build tools use the Keytool utility (included in the JDK) to create a debug key. Because the SDK build tools created the debug key, they know the debug key's alias and password. Each time you compile your application in debug mode, the build tools use the debug key along with the Jarsigner utility (also included in the JDK) to sign your application's .apk file. Because the alias and password are known to the SDK build tools, the tools don't need to prompt you for the debug key's alias and password each time you compile.
When you build in release mode you use your own private key to sign your application. If you don't have a private key, you can use the Keytool utility to create one for you. When you compile your application in release mode, the build tools use your private key along with the Jarsigner utility to sign your application's .apk file. Because the certificate and private key you use are your own, you must provide the password for the keystore and key alias.
The debug signing process happens automatically when you run or debug your application using Eclipse with the ADT plugin. Debug signing also happens automatically when you use the Ant build script with the debug option. You can automate the release signing process by using the Eclipse Export Wizard or by modifying the Ant build script and building with the release option.
When you start JVM you define how much RAM it can use use for processing. JVM divides this into certain memory locations for its processing purpose, two of those are Stack & Heap.
Out of memory error is related to Heap. If you have large objects (or) referenced objects in memory, then you will see Out of memory error . If you have strong references to objects, then GC can't clean the memory space allocated for that object. When JVM tries to allocate memory for new object and not enough space available it throws Out of memory error because it can't allocate required amount of memory.
How to avoid: Make sure unnecessary objects are available for GC.
Stack Overflow error is related to stack. All your local variables and methods calls related data will be on stack. For every method call one stack frame will be created and local as well as method call related data will be placed inside the stack frame. Once method execution is completed, stack frame will be removed. ONE WAY to reproduce this is, have infinite loop for method call, you will see Stack Overflow error, because stack frame will be populated with method data for every call but it won't be freed (removed).
How to avoid: Make sure method calls are ending (not in infinite loop).
Here are few differences between stack and heap memory in Java:
1) Main difference between heap and stack is that stack memory is used to store local variables and function call, while heap memory is used to store objects in Java. No matter, where object is created in code e.g. as member variable, local variable or class variable, they are always created inside heap space in Java.
2) Each Thread in Java has there own stack which can be specified using -Xss JVM parameter, similarly you can also specify heap size of Java program using JVM option -Xms and -Xmx where -Xms is starting size of heap and -Xmx is maximum size of java heap.
3) If there is no memory left in stack for storing function call or local variable, JVM will throw java.lang.StackOverFlowError, while if there is no more heap space for creating object, JVM will throw java.lang.OutOfMemoryError: Java Heap Space.
4) If you are using Recursion on which method calls itself, You can quickly fill up stack memory. Another difference between stack and heap is that size of stack memory is lot lesser than size of heap memory in Java.
5) Variables stored in stacks are only visible to the owner Thread, while objects created in heap are visible to all thread. In other words stack memory is kind of private memory of Java Threads, while heap memory is shared among all threads.
Difference between debug.apk and release.apk android ?
The difference between debug and release builds is for example, that you can get the log output from the debug build but not from the release build.
Debug builds can be signed with the default keystore, the release builds have to be signed with your created keystore.
The Android build process signs your application differently depending on which build mode you use to build your application.
There are two build modes: debug mode and release mode.
You use debug mode when you are developing and testing your application.
You use release mode when you want to build a release version of your application that you can distribute directly to users or publish on an application marketplace such as Google Play.
When you build in debug mode the Android SDK build tools use the Keytool utility (included in the JDK) to create a debug key. Because the SDK build tools created the debug key, they know the debug key's alias and password. Each time you compile your application in debug mode, the build tools use the debug key along with the Jarsigner utility (also included in the JDK) to sign your application's .apk file. Because the alias and password are known to the SDK build tools, the tools don't need to prompt you for the debug key's alias and password each time you compile.
When you build in release mode you use your own private key to sign your application. If you don't have a private key, you can use the Keytool utility to create one for you. When you compile your application in release mode, the build tools use your private key along with the Jarsigner utility to sign your application's .apk file. Because the certificate and private key you use are your own, you must provide the password for the keystore and key alias.
The debug signing process happens automatically when you run or debug your application using Eclipse with the ADT plugin. Debug signing also happens automatically when you use the Ant build script with the debug option. You can automate the release signing process by using the Eclipse Export Wizard or by modifying the Ant build script and building with the release option.
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