Builder 模式的适用场景
1、 创建的对象参数比较多，较复杂。
2、构建过程中，步骤相同，但因引入的参数不同可导致对象不同。
实现过程：
public class PhoneState { private int id; private String ram; private String rom; private float system_version;
PhoneState(Builder builder){ this.id = builder.id; this.ram = builder.ram; this.rom = builder.rom; this.system_version = builder.system_version;
} public static class Builder{ private int id; private String ram; private String rom; private float system_version; public Builder(int id){ this.id = id;
} public Builder ram(String ram){ this.ram = ram; return this;
} public Builder rom(String rom){ this.rom = rom; return this;
} public Builder system_version(float system_version){ this.system_version = system_version; return this;
} public PhoneState build(){ return new PhoneState(this);
}
} @Override
public String toString() { return "PhoneState [id=" + id + ", ram=" + ram + ", rom=" + rom + ", system_version=" + system_version +"]";
}
}调用：
public class MainActivity extends AppCompatActivity { @Override
protected void onCreate(Bundle savedInstanceState) { super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
PhoneState phoneState = new PhoneState.Builder(1)
.ram("8GB")
.rom("128GB")
.system_version(7.1f)
.build();
Log.e("ACETEST", "phoneState: " + phoneState.toString() );
}
}打印：
PhoneState [id=1, ram=8GB, rom=128GB, system_version=7.1]