Stack in java 64 bit

Java Virtual Machine (JVM) Stack Area

For every thread, JVM creates a separate stack at the time of thread creation. The memory for a Java Virtual Machine stack does not need to be contiguous. The Java virtual machine only performs two operations directly on Java stacks: it pushes and pops frames. And stack for a particular thread may be termed as Run – Time Stack. Every method call performed by that thread is stored in the corresponding run-time stack including parameters, local variables, intermediate computations, and other data. After completing a method, the corresponding entry from the stack is removed. After completing all method calls the stack becomes empty and that empty stack is destroyed by the JVM just before terminating the thread. The data stored in the stack is available for the corresponding thread and not available to the remaining threads. Hence we can say local data thread-safe. Each entry in the stack is called Stack Frame or Activation Record.

Stack Frame Structure
The stack frame basically consists of three parts: Local Variable Array, Operand Stack & Frame Data. When JVM invokes a Java method, first it checks the class data to determine the number of words (size of the local variable array and operand stack, which is measured in words for each individual method) required by the method in the local variables array and operand stack. It creates a stack frame of the proper size for invoked method and pushes it onto the Java stack.

1. Local Variable Array (LVA):

• The local variables part of the stack frame is organized as a zero-based array of words.
• It contains all parameters and local variables of the method.
• Each slot or entry in the array is of 4 Bytes.
• Values of type int, float, and reference occupy 1 entry or slot in the array i.e. 4 bytes.
• Values of double and long occupy 2 consecutive entries in the array i.e. 8 bytes total.
• Byte, short, and char values will be converted to int type before storing and occupy 1 slot i.e. 4 Bytes.
• But the way of storing Boolean values is varied from JVM to JVM. But most of the JVM gives 1 slot for Boolean values in the local variable array.
• The parameters are placed into the local variable array first, in the order in which they are declared.
• For Example: Let us consider a class Example having a method bike() then the local variable array will be as shown in the below diagram:

// Class Declaration class Example < public void bike(int i, long l, float f, double d, Object o, byte b) < >>

2. Operand Stack (OS):

• JVM uses operand stack as workspace like rough work or we can say for storing intermediate calculation’s result.
• The operand stack is organized as an array of words like a local variable array. But this is not accessed by using an index like local variable array rather it is accessed by some instructions that can push the value to the operand stack and some instructions that can pop values from the operand stack and some instructions that can perform required operations.
• For Example: Here is how a JVM will use this below code that would subtract two local variables that contain two ints and store the int result in a third local variable:

• So here first two instructions iload_0 and iload_1 will push the values in the operand stack from a local variable array. And instruction isub will subtract these two values and store the result back to the operand stack and after istore_2 the result will pop out from the operand stack and will store into a local variable array at position 2.

3. Frame Data (FD):

• It contains all symbolic references (constant pool resolution) and normal method returns related to that particular method.
• It also contains a reference to the Exception table which provides the corresponding catch block information in the case of exceptions.

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Class Stack

The Stack class represents a last-in-first-out (LIFO) stack of objects. It extends class Vector with five operations that allow a vector to be treated as a stack. The usual push and pop operations are provided, as well as a method to peek at the top item on the stack, a method to test for whether the stack is empty , and a method to search the stack for an item and discover how far it is from the top.

When a stack is first created, it contains no items.

A more complete and consistent set of LIFO stack operations is provided by the Deque interface and its implementations, which should be used in preference to this class. For example:

 Deque stack = new ArrayDeque();

Field Summary

Fields declared in class java.util.Vector

Fields declared in class java.util.AbstractList

Constructor Summary

Method Summary

Methods declared in class java.util.Vector

Methods declared in class java.lang.Object

Methods declared in interface java.util.Collection

Methods declared in interface java.util.List

Constructor Details

Stack

Method Details

push

pop

peek

empty

search

Returns the 1-based position where an object is on this stack. If the object o occurs as an item in this stack, this method returns the distance from the top of the stack of the occurrence nearest the top of the stack; the topmost item on the stack is considered to be at distance 1 . The equals method is used to compare o to the items in this stack.

Report a bug or suggest an enhancement
For further API reference and developer documentation see the Java SE Documentation, which contains more detailed, developer-targeted descriptions with conceptual overviews, definitions of terms, workarounds, and working code examples. Other versions.
Java is a trademark or registered trademark of Oracle and/or its affiliates in the US and other countries.
Copyright © 1993, 2023, Oracle and/or its affiliates, 500 Oracle Parkway, Redwood Shores, CA 94065 USA.
All rights reserved. Use is subject to license terms and the documentation redistribution policy.

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Class Stack

The Stack class represents a last-in-first-out (LIFO) stack of objects. It extends class Vector with five operations that allow a vector to be treated as a stack. The usual push and pop operations are provided, as well as a method to peek at the top item on the stack, a method to test for whether the stack is empty , and a method to search the stack for an item and discover how far it is from the top.

When a stack is first created, it contains no items.

A more complete and consistent set of LIFO stack operations is provided by the Deque interface and its implementations, which should be used in preference to this class. For example:

 Deque stack = new ArrayDeque();

Field Summary

Fields declared in class java.util.Vector

Fields declared in class java.util.AbstractList

Constructor Summary

Method Summary

Methods declared in class java.util.Vector

Methods declared in class java.lang.Object

Methods declared in interface java.util.Collection

Methods declared in interface java.util.List

Constructor Details

Stack

Method Details

push

pop

peek

empty

search

Returns the 1-based position where an object is on this stack. If the object o occurs as an item in this stack, this method returns the distance from the top of the stack of the occurrence nearest the top of the stack; the topmost item on the stack is considered to be at distance 1 . The equals method is used to compare o to the items in this stack.

Report a bug or suggest an enhancement
For further API reference and developer documentation see the Java SE Documentation, which contains more detailed, developer-targeted descriptions with conceptual overviews, definitions of terms, workarounds, and working code examples. Other versions.
Java is a trademark or registered trademark of Oracle and/or its affiliates in the US and other countries.
Copyright © 1993, 2023, Oracle and/or its affiliates, 500 Oracle Parkway, Redwood Shores, CA 94065 USA.
All rights reserved. Use is subject to license terms and the documentation redistribution policy.

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Stack in java 64 bit

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