org.glassfish.hk2.utilities.general.GeneralUtilities Maven / Gradle / Ivy
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package org.glassfish.hk2.utilities.general;
import java.lang.reflect.Array;
import org.glassfish.hk2.utilities.general.internal.WeakHashClockImpl;
import org.glassfish.hk2.utilities.general.internal.WeakHashLRUImpl;
/**
* This class contains utilities useful for any code
*
* @author jwells
*
*/
public class GeneralUtilities {
/**
* Returns true if a is equals to b, or both
* and and b are null. Is safe even if
* a or b is null. If a or b is null but
* the other is not null, this returns false
*
* @param a A possibly null object to compare
* @param b A possibly null object to compare
* @return true if equal, false if not
*/
public static boolean safeEquals(Object a, Object b) {
if (a == b) return true;
if (a == null) return false;
if (b == null) return false;
return a.equals(b);
}
private static Class loadArrayClass(ClassLoader cl, String aName) {
Class componentType = null;
int[] dimensions = null;
int dot = 0;
while (componentType == null) {
char dotChar = aName.charAt(dot);
if (dotChar == '[') {
dot++;
continue;
}
dimensions = new int[dot];
for (int lcv = 0; lcv < dot; lcv++) {
dimensions[lcv] = 0;
}
if (dotChar == 'B') {
componentType = byte.class;
}
else if (dotChar == 'I') {
componentType = int.class;
}
else if (dotChar == 'J') {
componentType = long.class;
}
else if (dotChar == 'Z') {
componentType = boolean.class;
}
else if (dotChar == 'S') {
componentType = short.class;
}
else if (dotChar == 'C') {
componentType = char.class;
}
else if (dotChar == 'D') {
componentType = double.class;
}
else if (dotChar == 'F') {
componentType = float.class;
}
else {
if (dotChar != 'L') {
throw new IllegalArgumentException("Unknown array type " + aName);
}
if (aName.charAt(aName.length() - 1) != ';') {
throw new IllegalArgumentException("Badly formed L array expresion: " + aName);
}
String cName = aName.substring(dot + 1, aName.length() - 1);
componentType = loadClass(cl, cName);
if (componentType == null) return null;
}
}
Object retArray = Array.newInstance(componentType, dimensions);
return retArray.getClass();
}
/**
* Loads the class from the given classloader or returns null (does not throw).
* Property handles array classes as well
*
* @param cl The non-null classloader to load the class from
* @param cName The fully qualified non-null name of the class to load
* @return The class if it could be loaded from the classloader, or
* null if it could not be found for any reason
*/
public static Class loadClass(ClassLoader cl, String cName) {
if (cName.startsWith("[")) {
return loadArrayClass(cl, cName);
}
try {
return cl.loadClass(cName);
}
catch (Throwable th) {
return null;
}
}
/**
* Creates a weak hash clock
* @param isWeak if true this will keep weak keyes, if false the keys will
* be hard and will not go away even if they do not exist anywhere else
* but this cache
* @return A weak hash clock implementation
*/
public static WeakHashClock getWeakHashClock(boolean isWeak) {
return new WeakHashClockImpl(isWeak);
}
/**
* Creates a weak hash clock
* @param isWeak if true this will keep weak keyes, if false the keys will
* be hard and will not go away even if they do not exist anywhere else
* but this cache
* @return A weak hash clock implementation
*/
public static WeakHashLRU getWeakHashLRU(boolean isWeak) {
return new WeakHashLRUImpl(isWeak);
}
}