Item 1: Consider static factory methods instead of constructors

package java.lang;

public final class Boolean implements java.io.Serializable, Comparable<Boolean> {

    public static final Boolean TRUE = new Boolean(true);

    public static final Boolean FALSE = new Boolean(false);

....

    private final boolean value;

....

    public Boolean(boolean value) {
        this.value = value;
    }
....

    public static Boolean valueOf(boolean b) {
        return (b ? TRUE : FALSE);
    }
....
}