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。

 

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.

 

java.util.Scanner in = new Scanner(System.in);

 

java.io.Console cons = System.console();

String username = cons.readline("User name: ");

char[] passwd = cons.readPassword("Password: "); //Security issue

 

Formatting Output

    System.out.printf(), similar with printf() method from C

 

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

 

Array Sorting

    Arrays.sort(array); //this method used a tuned version of QS