Java Scanner?????

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Scanner??Java???????????????????Scanner????????????????????????????????????

1. ???Scanner

Scanner scanner = new Scanner(System.in);

2. ??????

next()??

next()????????????????????????????hasNext()??????????

if (scanner.hasNext()) {    String str = scanner.next();    System.out.println("???????" + str);}

nextLine()??

nextLine()???next()???????????????????????????

if (scanner.hasNextLine()) {    String str = scanner.nextLine();    System.out.println(str);}

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next()????????????????????

nextLine()????????????????????

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Scanner??????????????????????????????????????????

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Scanner scanner = new Scanner(System.in);System.out.println("?????");if (scanner.hasNextInt()) {    int i = scanner.nextInt();    System.out.println("?????" + i);} else {    System.out.println("????????");}System.out.println("??????");if (scanner.hasNextFloat()) {    float f = scanner.nextFloat();    System.out.println("???" + f);} else {    System.out.println("????????");}

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public static void main(String[] args) {    Scanner scanner = new Scanner(System.in);    double sum = 0;    int m = 0;    while (scanner.hasNextDouble()) {        double nextDouble = scanner.nextDouble();        m++;        sum += nextDouble;        System.out.println("????" + m + "????????sum=" + sum);    }    System.out.println(m + "?????:" + sum);    System.out.println(m + "???????:" + sum/m);    scanner.close();}