org.apache.commons.io.build

Class AbstractSupplier<T,B extends AbstractSupplier<T,B>>

java.lang.Object

org.apache.commons.io.build.AbstractSupplier<T,B>

Type Parameters:

T - the type of instances to build.

B - the type of builder subclass.

All Implemented Interfaces:

IOSupplier<T>

Direct Known Subclasses:

AbstractOrigin, AbstractOriginSupplier, SimplePathVisitor.AbstractBuilder, WildcardFileFilter.Builder

public abstract class AbstractSupplier<T,B extends AbstractSupplier<T,B>>
extends Object
implements IOSupplier<T>

Abstracts supplying an instance of T.

Extend this class to implement the builder pattern.

For example, here is a builder, a domain class, and a test.

The builder:

    /**
     * Builds Foo instances.
     */
    public static class Builder extends AbstractSupplier<Foo, Builder> {

        private String bar1;
        private String bar2;
        private String bar3;

        /**
         * Builds a new Foo.
         */
        @Override
        public Foo get() {
            return new Foo(bar1, bar2, bar3);
        }

        public Builder setBar1(final String bar1) {
            this.bar1 = bar1;
            return this;
        }

        public Builder setBar2(final String bar2) {
            this.bar2 = bar2;
            return this;
        }

        public Builder setBar3(final String bar3) {
            this.bar3 = bar3;
            return this;
        }
    }
 

The domain class:

    /**
     * Domain class.
     */
    public class Foo {

        public static Builder builder() {
            return new Builder();
        }

        private final String bar1;
        private final String bar2;
        private final String bar3;

        private Foo(final String bar1, final String bar2, final String bar3) {
            this.bar1 = bar1;
            this.bar2 = bar2;
            this.bar3 = bar3;
        }

        public String getBar1() {
            return bar1;
        }

        public String getBar2() {
            return bar2;
        }

        public String getBar3() {
            return bar3;
        }

    }
 

The test:

    @Test
    public void test() {
        final Foo foo = Foo.builder()
            .setBar1("value1")
            .setBar2("value2")
            .setBar3("value3")
            .get();
        assertEquals("value1", foo.getBar1());
        assertEquals("value2", foo.getBar2());
        assertEquals("value3", foo.getBar3());
    }
 

Constructor Summary

Constructors

Constructor and Description
AbstractSupplier() Constructs a new instance for subclasses.

Method Summary

Modifier and Type	Method and Description
protected B	asThis() Returns this instance typed as the subclass type B.

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Methods inherited from interface org.apache.commons.io.function.IOSupplier

asSupplier, get, getUnchecked

Constructor Detail

AbstractSupplier

public AbstractSupplier()

Constructs a new instance for subclasses.

Method Detail

asThis

protected B asThis()

Returns this instance typed as the subclass type B.

This is the same as the expression:

 (B) this
 

Returns:

this instance typed as the subclass type B.