java for each 循环 数组 对象遍历

语法

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

看个遍历数组实例

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();
  } 
}

输出

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

遍历enum对象

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);
    }
  }
}

结果

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

遍历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);
 
  }
}