リストに同じ要素が含まれていないかチェックしてから、他のリストに値を入力してください

Question

同じオブジェクトを持つリストが2つあります。

List<Object1> list1; 
List<Object1> list2; 

for (Object1 objectItem : list1.getList()) { 
    // I want to check if objectItem exists in list2 without using another for loop and then compare their other values 
    // Something like list2.getList().contains(objectItem).getThisValueMethod(); 
} 

これは可能ですか？

Answer 1

この例（Explanation in Comments）を考えてみましょう：

// Suppose you have two lists of Objects (Strings in this case) 
List<String> list1 = new ArrayList<String>(); 
List<String> list2 = new ArrayList<String>(); 

//fill them with some example data 
list1.add("1"); list1.add("2"); list1.add("3"); 
list2.add("0"); list2.add("1"); list2.add("2"); 

// Now you can use ONE for-loop as you asked to check equality 
for (String s : list1) { 
    if(list2.contains(s)){ // use contains() method which returns true if the Object found 
    // indexOf(Object) this method return the index of the given Object in the list 
    // get(int index) this return the OBJECT from the list 
    // and because Java works by passing reference of object -> you can directly invoke any method 
    // that is originally in that Object Class 

     list2.get(list2.indexOf(s)); // you can invoke a method on it 
    // because in this case it's a String I can invoke any method from Class String 
    // on the the above-object, for example 
     list2.get(list2.indexOf(s)).trim(); // this method to remove leading spaces.. and so on 

     System.out.println(list2.get(list2.indexOf(s))); // for testing 
    } 
}