HarmonyOS 定义静态方法与常量的代码区别

export class Test { 
  static readonly KEY: string = 'key'; 
  static KEY1: string = 'key'; 
 
  static log() { 
  } 
} 
 
/** 
 * ============分割线============ 
 */ 
export class Test1 { 
  readonly KEY: string = 'KEY' 
  KEY1: string = 'KEY1' 
 
  log() { 
 
  } 
} 
export default new Test1() 
 
/** 
 * ============分割线============ 
 */ 
export class Test2 { 
  private static instance: Test2; 
  private constructor() { 
  } 
 
  public static getInstance(): Test2 { 
    if (!Test2.instance) { 
      Test2.instance = new Test2(); 
    } 
    return Test2.instance; 
  } 
  readonly KEY: string = 'KEY' 
  KEY1: string = 'KEY1' 
 
  log() { 
 
  } 
}