Chapter 3 Fundamental Programming Structures in Java[CJ 8e NOTE]
这一章介绍Java的基础结构，如8种基本数据类型、数组、控制等。
我记一下平时用的比较少的。
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StringBuilder, a class that can be used to build a long string from many pieces, which is more efficient than concatentation. StringBuilder should used in a single thread.Instead, StringBuffer allows mutiple threads to operate.
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java.util.Scanner in = new Scanner(System.in);
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java.io.Console cons = System.console();
String username = cons.readline("User name: ");
char[] passwd = cons.readPassword("Password: "); //Security issue
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Formatting Output
??? System.out.printf(), similar with printf() method from C
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Array Copying
??? int[] arrayA = arrayB; //both variables refer to the same array
??? int[] arrayA = Arrays.copyOf(arrayB, arrayB.length); //copy all values of arrayB to a new array arrayA
??? System.arraycopy(fromArray, fromIndex, toArray, toIndex, count); //the toArray must have suffient space to hold the copied elements
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Array Sorting
??? Arrays.sort(array); //this method used a tuned version of QS
