List methods of a class using Java Reflection
The methods of a class can be listed using the java.lang.Class.getDeclaredMethods() method. This method returns an array that contains all the Method objects with public, private, protected and default access. However, the inherited methods are not included.
Also, the getDeclaredMethods() method returns a zero length array if the class or interface has no methods or if a primitive type, array class or void is represented in the Class object.
A program that demonstrates this is given as follows −
Example
import java.lang.reflect.*; public class Demo < public static void main(String[] args) < Class c = Thread.class; Method[] methods = c.getDeclaredMethods(); for(int i = 0; i < methods.length; i++) < System.out.println("The method is: " + methods[i].toString()); >> > Output
The method is: public void java.lang.Thread.run() The method is: private void java.lang.Thread.exit() The method is: private void java.lang.Thread.dispatchUncaughtException(java.lang.Throwable) The method is: public java.lang.String java.lang.Thread.toString() The method is: protected java.lang.Object java.lang.Thread.clone() throws java.lang.CloneNotSupportedException The method is: public boolean java.lang.Thread.isInterrupted() The method is: private native boolean java.lang.Thread.isInterrupted(boolean) The method is: public static native java.lang.Thread java.lang.Thread.currentThread() The method is: private static native void java.lang.Thread.registerNatives() The method is: public final java.lang.String java.lang.Thread.getName() The method is: public synchronized void java.lang.Thread.start() The method is: public final synchronized void java.lang.Thread.join(long,int) throws java.lang.InterruptedException The method is: public final synchronized void java.lang.Thread.join(long) throws java.lang.InterruptedException The method is: public final void java.lang.Thread.join() throws java.lang.InterruptedException The method is: private void java.lang.Thread.init(java.lang.ThreadGroup,java.lang.Runnable,java.lang.String,long,java.security.AccessControlContext,boolean) The method is: private void java.lang.Thread.init(java.lang.ThreadGroup,java.lang.Runnable,java.lang.String,long) The method is: public final java.lang.ThreadGroup java.lang.Thread.getThreadGroup() The method is: public java.lang.StackTraceElement[] java.lang.Thread.getStackTrace() The method is: public static native boolean java.lang.Thread.holdsLock(java.lang.Object) The method is: public final void java.lang.Thread.checkAccess() The method is: public static void java.lang.Thread.dumpStack() The method is: public static native void java.lang.Thread.yield() The method is: public final void java.lang.Thread.setPriority(int) The method is: public final void java.lang.Thread.setDaemon(boolean) The method is: private static synchronized int java.lang.Thread.nextThreadNum() The method is: private static synchronized long java.lang.Thread.nextThreadID() The method is: void java.lang.Thread.blockedOn(sun.nio.ch.Interruptible) The method is: public static native void java.lang.Thread.sleep(long) throws java.lang.InterruptedException The method is: public static void java.lang.Thread.sleep(long,int) throws java.lang.InterruptedException The method is: private native void java.lang.Thread.start0() The method is: public final synchronized void java.lang.Thread.stop(java.lang.Throwable) The method is: public final void java.lang.Thread.stop() The method is: public void java.lang.Thread.interrupt() The method is: public static boolean java.lang.Thread.interrupted() The method is: public void java.lang.Thread.destroy() The method is: public final native boolean java.lang.Thread.isAlive() The method is: public final void java.lang.Thread.suspend() The method is: public final void java.lang.Thread.resume() The method is: public final int java.lang.Thread.getPriority() The method is: public final synchronized void java.lang.Thread.setName(java.lang.String) The method is: public static int java.lang.Thread.activeCount() The method is: public static int java.lang.Thread.enumerate(java.lang.Thread[]) The method is: public native int java.lang.Thread.countStackFrames() The method is: public final boolean java.lang.Thread.isDaemon() The method is: public java.lang.ClassLoader java.lang.Thread.getContextClassLoader() The method is: public void java.lang.Thread.setContextClassLoader(java.lang.ClassLoader) The method is: public static java.util.Map java.lang.Thread.getAllStackTraces() The method is: private static boolean java.lang.Thread.isCCLOverridden(java.lang.Class) The method is: private static boolean java.lang.Thread.auditSubclass(java.lang.Class) The method is: private static native java.lang.StackTraceElement[][] java.lang.Thread.dumpThreads(java.lang.Thread[]) The method is: private static native java.lang.Thread[] java.lang.Thread.getThreads() The method is: public long java.lang.Thread.getId() The method is: public java.lang.Thread$State java.lang.Thread.getState() The method is: public static void java.lang.Thread.setDefaultUncaughtExceptionHandler(java.lang.Thread$UncaughtExceptionHandler) The method is: public static java.lang.Thread$UncaughtExceptionHandler java.lang.Thread.getDefaultUncaughtExceptionHandler() The method is: public java.lang.Thread$UncaughtExceptionHandler java.lang.Thread.getUncaughtExceptionHandler() The method is: public void java.lang.Thread.setUncaughtExceptionHandler(java.lang.Thread$UncaughtExceptionHandler) The method is: static void java.lang.Thread.processQueue(java.lang.ref.ReferenceQueue,java.util.concurrent.ConcurrentMap) The method is: private native void java.lang.Thread.setPriority0(int) The method is: private native void java.lang.Thread.stop0(java.lang.Object) The method is: private native void java.lang.Thread.suspend0() The method is: private native void java.lang.Thread.resume0() The method is: private native void java.lang.Thread.interrupt0() The method is: private native void java.lang.Thread.setNativeName(java.lang.String)
Interface List
An ordered collection (also known as a sequence). The user of this interface has precise control over where in the list each element is inserted. The user can access elements by their integer index (position in the list), and search for elements in the list.
Unlike sets, lists typically allow duplicate elements. More formally, lists typically allow pairs of elements e1 and e2 such that e1.equals(e2) , and they typically allow multiple null elements if they allow null elements at all. It is not inconceivable that someone might wish to implement a list that prohibits duplicates, by throwing runtime exceptions when the user attempts to insert them, but we expect this usage to be rare.
The List interface places additional stipulations, beyond those specified in the Collection interface, on the contracts of the iterator , add , remove , equals , and hashCode methods. Declarations for other inherited methods are also included here for convenience.
The List interface provides four methods for positional (indexed) access to list elements. Lists (like Java arrays) are zero based. Note that these operations may execute in time proportional to the index value for some implementations (the LinkedList class, for example). Thus, iterating over the elements in a list is typically preferable to indexing through it if the caller does not know the implementation.
The List interface provides a special iterator, called a ListIterator , that allows element insertion and replacement, and bidirectional access in addition to the normal operations that the Iterator interface provides. A method is provided to obtain a list iterator that starts at a specified position in the list.
The List interface provides two methods to search for a specified object. From a performance standpoint, these methods should be used with caution. In many implementations they will perform costly linear searches.
The List interface provides two methods to efficiently insert and remove multiple elements at an arbitrary point in the list.
Note: While it is permissible for lists to contain themselves as elements, extreme caution is advised: the equals and hashCode methods are no longer well defined on such a list.
Some list implementations have restrictions on the elements that they may contain. For example, some implementations prohibit null elements, and some have restrictions on the types of their elements. Attempting to add an ineligible element throws an unchecked exception, typically NullPointerException or ClassCastException . Attempting to query the presence of an ineligible element may throw an exception, or it may simply return false; some implementations will exhibit the former behavior and some will exhibit the latter. More generally, attempting an operation on an ineligible element whose completion would not result in the insertion of an ineligible element into the list may throw an exception or it may succeed, at the option of the implementation. Such exceptions are marked as «optional» in the specification for this interface.
Unmodifiable Lists
- They are unmodifiable. Elements cannot be added, removed, or replaced. Calling any mutator method on the List will always cause UnsupportedOperationException to be thrown. However, if the contained elements are themselves mutable, this may cause the List’s contents to appear to change.
- They disallow null elements. Attempts to create them with null elements result in NullPointerException .
- They are serializable if all elements are serializable.
- The order of elements in the list is the same as the order of the provided arguments, or of the elements in the provided array.
- The lists and their subList views implement the RandomAccess interface.
- They are value-based. Programmers should treat instances that are equal as interchangeable and should not use them for synchronization, or unpredictable behavior may occur. For example, in a future release, synchronization may fail. Callers should make no assumptions about the identity of the returned instances. Factories are free to create new instances or reuse existing ones.
- They are serialized as specified on the Serialized Form page.
This interface is a member of the Java Collections Framework.