Android 设计模式

1.单例模式：

public class Singleton {    private static volatile Singleton instance = null;    private Singleton(){    }    public static Singleton getInstance() {        if (instance == null) {            synchronized (Singleton.class) {                if (instance == null) {                    instance = new Singleton();                }            }        }        return instance;    }}

2.Build模式

public class Person {    private String name;    private int age;    private double height;    private double weight;    privatePerson(Builder builder) {        this.name=builder.name;        this.age=builder.age;        this.height=builder.height;        this.weight=builder.weight;    }    public String getName() {        return name;    }    public void setName(String name) {        this.name = name;    }    public int getAge() {        return age;    }    public void setAge(int age) {        this.age = age;    }    public double getHeight() {        return height;    }    public void setHeight(double height) {        this.height = height;    }    public double getWeight() {        return weight;    }    public void setWeight(double weight) {        this.weight = weight;    }    static class Builder{        private String name;        private int age;        private double height;        private double weight;        public Builder name(String name){            this.name=name;            return this;        }        public Builder age(int age){            this.age=age;            return this;        }        public Builder height(double height){            this.height=height;            return this;        }        public Builder weight(double weight){            this.weight=weight;            return this;        }        public Person build(){            return new Person(this);        }    }

调用方法：

Person.Builder builder=new Person.Builder();Person person=builder        .name("张三")        .age(18)        .height(178.5)        .weight(67.4)        .build();