BAEL-4007 Interface Segregation Principle (#9579)

Co-authored-by: Dhrubajyoti Bhattacharjee <dhrubajyoti.bhattacharjee@ul.com>

patterns/solid/src/main/java/com/baeldung/i/fixed/Bank.java

@@ -0,0 +1,5 @@
+package com.baeldung.i.fixed;
+
+public interface Bank extends Payment {
+    void initiatePayments();
+}

patterns/solid/src/main/java/com/baeldung/i/fixed/BankPayment.java

@@ -0,0 +1,21 @@
+package com.baeldung.i.fixed;
+
+import java.util.List;
+
+public class BankPayment implements Bank {
+
+    @Override
+    public void initiatePayments() {
+
+    }
+
+    @Override
+    public Object status() {
+        return null;
+    }
+
+    @Override
+    public List<Object> getPayments() {
+        return null;
+    }
+}

patterns/solid/src/main/java/com/baeldung/i/fixed/Loan.java

@@ -0,0 +1,6 @@
+package com.baeldung.i.fixed;
+
+public interface Loan extends Payment {
+    void intiateLoanSettlement();
+    void initiateRePayment();
+}

patterns/solid/src/main/java/com/baeldung/i/fixed/LoanPayment.java

@@ -0,0 +1,26 @@
+package com.baeldung.i.fixed;
+
+import java.util.List;
+
+public class LoanPayment implements Loan {
+
+    @Override
+    public void intiateLoanSettlement() {
+
+    }
+
+    @Override
+    public void initiateRePayment() {
+
+    }
+
+    @Override
+    public Object status() {
+        return null;
+    }
+
+    @Override
+    public List<Object> getPayments() {
+        return null;
+    }
+}

patterns/solid/src/main/java/com/baeldung/i/fixed/Payment.java

@@ -0,0 +1,8 @@
+package com.baeldung.i.fixed;
+
+import java.util.List;
+
+public interface Payment {
+    Object status();
+    List<Object> getPayments();
+}

patterns/solid/src/main/java/com/baeldung/i/polluted/BankPayment.java

@@ -0,0 +1,32 @@
+package com.baeldung.i.polluted;
+
+import java.util.Collections;
+import java.util.List;
+
+public class BankPayment implements Payment {
+
+    @Override
+    public void initiatePayments() {
+
+    }
+
+    @Override
+    public Object status() {
+        return null;
+    }
+
+    @Override
+    public List<Object> getPayments() {
+        return Collections.emptyList();
+    }
+
+    @Override
+    public void intiateLoanSettlement() {
+        throw new UnsupportedOperationException("This is not a loan payment");
+    }
+
+    @Override
+    public void initiateRePayment() {
+        throw new UnsupportedOperationException("This is not a loan payment");
+    }
+}

patterns/solid/src/main/java/com/baeldung/i/polluted/LoanPayment.java

@@ -0,0 +1,31 @@
+package com.baeldung.i.polluted;
+
+import java.util.List;
+
+public class LoanPayment implements Payment {
+
+    @Override
+    public void initiatePayments() {
+
+    }
+
+    @Override
+    public Object status() {
+        return null;
+    }
+
+    @Override
+    public List<Object> getPayments() {
+        return null;
+    }
+
+    @Override
+    public void intiateLoanSettlement() {
+
+    }
+
+    @Override
+    public void initiateRePayment() {
+
+    }
+}

patterns/solid/src/main/java/com/baeldung/i/polluted/Payment.java

@@ -0,0 +1,13 @@
+package com.baeldung.i.polluted;
+
+import java.util.List;
+
+public interface Payment {
+    void initiatePayments();
+    Object status();
+    List<Object> getPayments();
+
+    //Loan related methods
+    void intiateLoanSettlement();
+    void initiateRePayment();
+}