创建数据类

data class Customer(val name: String, val email: String)

上述代码会创建一个Customer类，并包含以下功能：

• 所有属性的getter和setter
• equals()方法
• hashCode()方法
• toString()方法
• copy()方法
• component1() , component2() , …方法，分别对应定义的属性

反编译上述的class文件得到如下结果(并未把所有的方法内容列出)：

public final class Customer {
    @NotNull
    private final String email;
    @NotNull
    private final String name;

    @NotNull
    public final String component1() {
        return this.name;
    }

    @NotNull
    public final String component2() {
        return this.email;
    }

    @NotNull
    public final Customer copy(@NotNull String name, @NotNull String email) {
        Intrinsics.checkParameterIsNotNull(name, "name");
        Intrinsics.checkParameterIsNotNull(email, "email");
        return new Customer(name, email);
    }

    public boolean equals(java.lang.Object r3) {
        ......
    }

    public int hashCode() {
        int i = 0;
        String str = this.name;
        int hashCode = (str != null ? str.hashCode() : 0) * 31;
        String str2 = this.email;
        if (str2 != null) {
            i = str2.hashCode();
        }
        return hashCode + i;
    }

    public String toString() {
        return "Customer(name=" + this.name + ", email=" + this.email + ")";
    }

    public Customer(@NotNull String name, @NotNull String email) {
        Intrinsics.checkParameterIsNotNull(name, "name");
        Intrinsics.checkParameterIsNotNull(email, "email");
        this.name = name;
        this.email = email;
    }

    @NotNull
    public final String getEmail() {
        return this.email;
    }

    @NotNull
    public final String getName() {
        return this.name;
    }
}