java for each 迴圈 數組 對象遍曆

java for each 迴圈 數組 對象遍曆

文法

for(type itr-var : iterableobj) statement-block

看個遍曆數組執行個體

public class mainclass {
  public static void main(string args[]) {
    int nums[] = { 1, 2, 3, 4, 5, 6, 7, 8, 9, 10 };
 
    for(int x : nums) {
      system.out.print(x + " ");
      x = x * 10; // no effect on nums
    }
  
    system.out.println();

    for(int x : nums)
      system.out.print(x + " ");

    system.out.println();
  } 
}

輸出

1 2 3 4 5 6 7 8 9 10
1 2 3 4 5 6 7 8 9 10

遍曆enum對象

public class mainclass {
  enum season {
    spring, summer, fall, winter
  }

  public static void main(string[] args) {
    for (season season : season.values()) {
      system.out.println(" the season is now " + season);
    }
  }
}

結果

the season is now spring
 the season is now summer
 the season is now fall
 the season is now winter

遍曆arraylist

import java.util.arraylist;
 
public class mainclass {
   
  public static void main(string args[]) {
    arraylist<double> list = new arraylist<double>();

    list.add(10.14);
    list.add(20.22);
    list.add(30.78);
    list.add(40.46);

    double sum = 0.0;
    for(double itr : list)
      sum = sum + itr;
    system.out.println(sum);
 
  }
}