1Z0-829 practice questions 1–10

1. Question 1 · 52 in bank

   Given the code fragment:

   

   and

   

   Which is true?

   • AThe program prints t1 : 1 : t2 : 1: t1 : 2 : t2 : 2 : in random order.
   • BThe program prints t1 : 1 : t2 : 1: t1 : 2 : t2 : 2 :
   • CThe program prints t1 : 1 : t2 : 1: t1 : 1 : t2 : 1 : indefinitely.
   • DThe program prints an exception.

   Show answer

   Answer: A

   Explanation

   // Result: // t2 : 1 : t2 : 2 : t1 : 1 : t1 : 2 : // t1 : 1 : t2 : 1 : t2 : 2 : t1 : 2 : // t1 : 1 : t2 : 1 : t1 : 2 : t2 : 2 : // t1 : 1 : t2 : 1 : t1 : 2 : t2 : 2 :

   Source: Adapted from community discussion — james2033

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2. Question 2 · 52 in bank

   Given:

   

   What is the result?

   • ACompilation fails.
   • Bthere
   • Chello
   • DA NumberFormatException is thrown.

   Show answer

   Answer: C

   Explanation

   package q10; public class Main { void print(int i) { System.out.println("hello"); } void print(long j) { System.out.println("there"); } public static void main(String[] args) { new Main().print(0b1101_1010); } } // Result: // hello

   Source: Adapted from community discussion — james2033

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3. Question 3 · 52 in bank

   Given the code fragment:

   

   Which set of class definitions compiles?

   • Ainterface Story extends SInt {} interface Art extends SInt {}
   • Bpublic interface Story extends SInt {} public interface Art extends SInt {}
   • Csealed interface Story extends SInt {} non-sealed class Art implements SInt {}
   • Dnon-sealed interface Story extends SInt {} non-sealed interface Art extends SInt {}
   • Enon-sealed interface Story extends SInt {} class Art implements SInt {}

   Show answer

   Answer: D

   Explanation

   The right option is D. non-sealed interface Story extends SInt {} non-sealed interface Art extends SInt {}, because the class in option E require an modifier

   Source: Adapted from community discussion — Tojose

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4. Question 4 · 52 in bank

   Given:

   

   What is the result?

   • AmA
   • BmB mA
   • CmB
   • DmB mC

   Show answer

   Answer: D

   Explanation

   package q12; class A { public void mA() { System.out.println("mA"); } } class B extends A { public void mB() { System.out.println("mB"); } } class C extends B { public void mC() { System.out.println("mC"); } } public class App { public static void main(String[] args) { A bobj = new B(); A cobj = new C(); if (cobj instanceof B v) { v.mB(); if (v instanceof C v1) { v1.mC(); } else { cobj.mA(); } } } } // Result: // mB // mC

   Source: Adapted from community discussion — james2033

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5. Question 5 · 52 in bank

   Given the code fragment:

   

   What is the result?

   • AABBCDE // the order of elements is unpredictable
   • BABCDE
   • CABCDE // the order of elements is unpredictable
   • DADEABCB // the order of elements is unpredictable

   Show answer

   Answer: C

   Explanation

   package q13; import java.util.stream.Stream; public class Q13 { public static void main(String[] args) { Stream s1 = Stream.of("A", "B", "C", "B"); Stream s2 = Stream.of("A", "D", "E"); Stream.concat(s1, s2).parallel().distinct().forEach(element -> System.out.print(element)); } } // Result: // CEDBA // CEDAB // CEDBA

   Source: Adapted from community discussion — james2033

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6. Question 6 · 52 in bank

   Given:

   

   What is the result?

   • A{bicycle=7, car=7, motorcycle=7, truck=7}
   • B{3:bicycle, 0:car, 6:motorcycle, 5:truck}
   • CCompilation fails.
   • D{bicycle=1, car=3, motorcycle=1, truck=2}
   • E{bicycle, car, motorcycle, truck}

   Show answer

   Answer: D

   Explanation

   package q14; import java.util.Arrays; import java.util.Collections; import java.util.List; import java.util.Map; import java.util.function.Function; import java.util.stream.Collectors; public class Test { public static void main(String[] args) { List elements = Arrays.asList("car", "truck", "car", "bicycle", "car", "truck", "motorcycle"); Map outcome = elements.stream().collect(Collectors.groupingBy(Function.identity(), Collectors.counting())); System.out.println(outcome); } } // Result: // {motorcycle=1, bicycle=1, car=3, truck=2}

   Source: Adapted from community discussion — james2033

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7. Question 7 · 52 in bank

   Which statement is true about modules?

   • AOnly unnamed modules are on the module path.
   • BAutomatic and named modules are on the module path.
   • COnly automatic modules are on the module path.
   • DOnly named modules are on the module path.
   • EAutomatic and unnamed modules are on the module path.

   Show answer

   Answer: B

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8. Question 8 · 52 in bank

   Given the code fragment:

   

   Which code at line n1, obtains the java.io.Console object?

   • AConsole console = Console.getInstance();
   • BConsole console = System.console();
   • CConsole console = new Console(System.in);
   • DConsole console = new Console(new InputStreamReader(System.in));
   • EConsole console = System.console(System.in);

   Show answer

   Answer: B

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9. Question 9 · 52 in bank

   Given the content of the in.txt file: 0123456789 and the code fragment:

   

   What is the content of the out.txt file?

   • A012345678
   • B01234567801234
   • C01234567
   • D0123456789
   • E012345678901234
   • F0123456789234567

   Show answer

   Answer: F

   Explanation

   package q17; import java.io.FileNotFoundException; import java.io.FileReader; import java.io.FileWriter; import java.io.IOException; public class Q17 { public static void main(String[] args) throws Exception { char[] buffer = new char[8]; int count = 0; try (FileReader in = new FileReader("D:\\in.txt"); FileWriter out = new FileWriter("D:\\out.txt")) { while ((count = in.read(buffer)) != -1) { out.write(buffer); } } // catch (FileNotFoundException e) { // throw new RuntimeException(e); // } catch (IOException e) { // throw new RuntimeException(e); // } } } // Result: // 0123456789234567

   Source: Adapted from community discussion — james2033

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10. Question 10 · 52 in bank

    Given the code fragment:

    

    What is the result?

    • Atrue:true:false:false
    • Btrue:false:true:false
    • Ctrue:false:true:true
    • Dtrue:false:false:false

    Show answer

    Answer: D

    Explanation

    right option is D. copy paste into https://editor.javadevjournal.com/java-17-compiler.html and see for yourself: public class Main{ public static void main(String[] args){ String myStr = "Hello Java 17"; String myTextBlk1 =""" Hello Java 17"""; String myTextBlk2 =""" Hello Java 17 """; System.out.print(myStr.equals(myTextBlk1)+":"); System.out.print(myStr.equals(myTextBlk2)+":"); System.out.print(myTextBlk1.equals(myTextBlk2)+":"); System.out.println(myTextBlk1.intern() == myTextBlk2.intern()); } }

    Source: Adapted from community discussion — supersquax

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1Z0-829 practice, question 1. 52 questions available.