CSE143X Inheritance Example handout #20 Assuming that the following classes have been defined: public class One { public void method1() { System.out.println("One1"); } } public class Two extends One { public void method3() { System.out.println("Two3"); } } public class Three extends One { public void method2() { System.out.println("Three2"); method1(); } } public class Four extends Three { public void method1() { System.out.println("Four1"); super.method1(); } public void method3() { System.out.println("Four3"); } } And assuming the following variables have been defined: One var1 = new Two(); One var2 = new Three(); One var3 = new Four(); Three var4 = new Four(); Object var5 = new Three(); Object var6 = new One(); In the table below, indicate in the right-hand column the output produced by the statement in the left-hand column. If the statement produces more than one line of output, indicate the line breaks with slashes as in "a/b/c" to indicate three lines of output with "a" followed by "b" followed by "c". If the statement causes an error, fill in the right-hand column with either the phrase "compiler error" or "runtime error" to indicate when the error would be detected. Statement Output ------------------------------------------------------------ var1.method1(); ____________________________ var2.method1(); ____________________________ var3.method1(); ____________________________ var4.method1(); ____________________________ var5.method1(); ____________________________ var6.method1(); ____________________________ var4.method2(); ____________________________ var4.method3(); ____________________________ ((Two)var1).method2(); ____________________________ ((Three)var1).method2(); ____________________________ ((Two)var1).method3(); ____________________________ ((Four)var2).method1(); ____________________________ ((Four)var3).method1(); ____________________________ ((Four)var4).method3(); ____________________________ ((One)var5).method1(); ____________________________ ((Four)var5).method2(); ____________________________ ((Three)var5).method2(); ____________________________ ((One)var6).method1(); ____________________________ ((One)var6).method2(); ____________________________ ((Two)var6).method3(); ____________________________
Solution to CSE143X Inheritance Example 1. Inheritance Mystery. The output is as follows. Statement Output -------------------------------------------------- var1.method1(); One1 var2.method1(); One1 var3.method1(); Four1/One1 var4.method1(); Four1/One1 var5.method1(); compiler error var6.method1(); compiler error var4.method2(); Three2/Four1/One1 var4.method3(); compiler error ((Two)var1).method2(); compiler error ((Three)var1).method2(); runtime error ((Two)var1).method3(); Two3 ((Four)var2).method1(); runtime error ((Four)var3).method1(); Four1/One1 ((Four)var4).method3(); Four3 ((One)var5).method1(); One1 ((Four)var5).method2(); runtime error ((Three)var5).method2(); Three2/One1 ((One)var6).method1(); One1 ((One)var6).method2(); compiler error ((Two)var6).method3(); runtime error
Stuart Reges
Last modified: Wed Nov 21 13:41:10 PST 2018