Builder Design Pattern

package com.sheting.design.pattern.demo3;

/**
 * @author SheTing
 * @Time 7:32
 */
public class Computer {
    //required parameters
    private String HDD;
    private String RAM;

    //optional parameters
    private boolean isGraphicsCardEnabled;
    private boolean isBluetoothEnabled;


    public String getHDD() {
        return HDD;
    }

    public String getRAM() {
        return RAM;
    }

    public boolean isGraphicsCardEnabled() {
        return isGraphicsCardEnabled;
    }

    public boolean isBluetoothEnabled() {
        return isBluetoothEnabled;
    }

    private Computer(ComputerBuilder builder) {
        this.HDD = builder.HDD;
        this.RAM = builder.RAM;
        this.isGraphicsCardEnabled = builder.isGraphicsCardEnabled;
        this.isBluetoothEnabled = builder.isBluetoothEnabled;
    }

    //Builder Class
    public static class ComputerBuilder {

        // required parameters
        private String HDD;
        private String RAM;

        // optional parameters
        private boolean isGraphicsCardEnabled;
        private boolean isBluetoothEnabled;

        public ComputerBuilder(String hdd, String ram) {
            this.HDD = hdd;
            this.RAM = ram;
        }

        public ComputerBuilder setGraphicsCardEnabled(boolean isGraphicsCardEnabled) {
            this.isGraphicsCardEnabled = isGraphicsCardEnabled;
            return this;
        }

        public ComputerBuilder setBluetoothEnabled(boolean isBluetoothEnabled) {
            this.isBluetoothEnabled = isBluetoothEnabled;
            return this;
        }

        public Computer build() {
            return new Computer(this);
        }

    }
}

package com.sheting.design.pattern.demo3;

/**
 * @author SheTing
 * @Time 7:34
 */
public class TestBuilderPattern {

    public static void main(String[] args) {
        //Using builder to get the object in a single line of code and
        //without any inconsistent state or arguments management issues
        Computer comp = new Computer.ComputerBuilder("500 GB", "2 GB")
                .setBluetoothEnabled(true)
                .setGraphicsCardEnabled(true)
                .build();
    }

}

Builder Design Pattern Example in JDK

• java.lang.StringBuilder#append() (unsynchronized)
• java.lang.StringBuffer#append() (synchronized)