13: String a = ""; 14: a += 2; 15: a += 'c'; 16: a += false; 17: if ( a == "2cfalse") System.out.println("=="); 18: if ( a.equals("2cfalse")) System.out.println("equals");
❌ A. Compile error on line 14. ❌ B. Compile error on line 15. ❌ C. Compile error on line 16. ❌ D. Compile error on another line. ❌ E. == ✅ F. equals ❌ G. An exception is thrown
Explanation: a += 2 expands to a = a + 2. A String concatenated with any other type gives a String. Lines 14, 15, and 16 all append to a, giving a result of "2cfalse". The if statement on line 18 returns false because the values of the two String objects are the same using object equality. The if statement on line 17 returns false because the two String objects are not the same in memory. One comes directly from the string pool and the other comes from building using String operations.
13: String a = ""; 14: a += 2; 15: a += 'c'; 16: a += false; 17: if ( a == "2cfalse") System.out.println("=="); 18: if ( a.equals("2cfalse")) System.out.println("equals");
❌ A. Compile error on line 14. ❌ B. Compile error on line 15. ❌ C. Compile error on line 16. ❌ D. Compile error on another line. ❌ E. == ✅ F. equals ❌ G. An exception is thrown
Explanation: a += 2 expands to a = a + 2. A String concatenated with any other type gives a String. Lines 14, 15, and 16 all append to a, giving a result of "2cfalse". The if statement on line 18 returns false because the values of the two String objects are the same using object equality. The if statement on line 17 returns false because the two String objects are not the same in memory. One comes directly from the string pool and the other comes from building using String operations.
BY Explanations “Top Java Quiz Questions”
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Bitcoin is built on a distributed digital record called a blockchain. As the name implies, blockchain is a linked body of data, made up of units called blocks that contain information about each and every transaction, including date and time, total value, buyer and seller, and a unique identifying code for each exchange. Entries are strung together in chronological order, creating a digital chain of blocks. “Once a block is added to the blockchain, it becomes accessible to anyone who wishes to view it, acting as a public ledger of cryptocurrency transactions,” says Stacey Harris, consultant for Pelicoin, a network of cryptocurrency ATMs. Blockchain is decentralized, which means it’s not controlled by any one organization. “It’s like a Google Doc that anyone can work on,” says Buchi Okoro, CEO and co-founder of African cryptocurrency exchange Quidax. “Nobody owns it, but anyone who has a link can contribute to it. And as different people update it, your copy also gets updated.”
Mr. Durov launched Telegram in late 2013 with his brother, Nikolai, just months before he was pushed out of VK, the Russian social-media platform he founded. Mr. Durov pitched his new app—funded with the proceeds from the VK sale—less as a business than as a way for people to send messages while avoiding government surveillance and censorship.
