Apexとインターフェイスクラス

01_InterfaceSample.cls

public interface InterfaceSample {
    String sampleMethod1();
    String sampleMethod2(Integer num);
}

02_ImplementsSample.cls

public with sharing class ImplementsSample implements InterfaceSample {

    public String sampleMethod1() {
        return 'サンプル１';
    }
    
    public String sampleMethod2(Integer num) {
        return 'サンプル２ : ' + String.valueOf(num);
    }
}

03_InterfaceSampleRun.cls

public with sharing class InterfaceSampleRun {

    /**
     * コンストラクタ
     */
    public InterfaceSampleRun() {
        ImplementsSample sample = new ImplementsSample();
        String result1 = sample.sampleMethod1();
        String result2 = sample.sampleMethod2(1000);

        System.debug(result1);
        System.debug(result2);
    }
}