如何打破多个foreach循环？

Question

我有四个foreach循环遍历集合并根据条件执行某些操作.

这是我现在写的代码:

boolean breakFlag = false;
String valueFromObj2 = null;
String valueFromObj4 = null;
for(Object1 object1: objects){
  for(Object2 object2: object1){
    // I get some value from object2
    valueFromObj2 = object2.getSomeValue();
    for(Object3 object3 : object2){
      for(Object4 object4: object3){
       // Finally I get some value from Object4.
       valueFromObj4 = object4.getSomeValue();
       // Compare with valueFromObj2 to decide either to break all the foreach loop
       breakFlag = compareTwoVariable(valueFromObj2, valueFromObj4 );
       if(breakFlag){break;}
      } // fourth loop ends here
      if(breakFlag){break;}
    } // third loop ends here
    if(breakFlag){break;}
  } // second loop ends here
  if(breakFlag){break;}
} // first loop ends here

主要对象(代码中的对象)来自第三方提供程序SDK,因此我无法更改该部分的任何内容.我想询问Stack Overflow社区是否有更好的方法来打破所有四个foreach循环.或者,如果有任何其他方法可以重构此代码,使其更具可读性和可维护性.

Answer 1

在最外层循环上使用标签,并在break要跳出所有循环时在语句中包含此标签.在下面的示例中,我已修改您的代码以使用标签OUTERMOST:

String valueFromObj2 = null;
String valueFromObj4 = null;
OUTERMOST: for(Object1 object1: objects){
  for(Object2 object2: object1){
    //I get some value from object2
    valueFromObj2 = object2.getSomeValue();
    for(Object3 object3 : object2){
      for(Object4 object4: object3){
        //Finally I get some value from Object4.
        valueFromObj4 = object4.getSomeValue();
        //Compare with valueFromObj2 to decide either to break all the foreach loop
        if( compareTwoVariable(valueFromObj2, valueFromObj4 )) {
          break OUTERMOST;
        }
      }//fourth loop ends here
    }//third loop ends here
  }//second loop ends here
}//first loop ends here

Answer 2

将所有循环提取到函数中并使用return.

Answer 3

您可以使用带标签的break语句.这种中断终止了外部陈述

请参阅break语句