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  • Java8新特性之forEach+Lambda 表达式遍历Map和List

    ============Java8之前的方式==========
    Map<String, Integer> items = new HashMap<>();
    items.put("A", 10);
    items.put("B", 20);
    items.put("C", 30);
    items.put("D", 40);
    items.put("E", 50);
    items.put("F", 60);
    for (Map.Entry<String, Integer> entry : items.entrySet()) {
        System.out.println("Item : " + entry.getKey() + " Count : " + entry.getValue());
    }
    ============forEach + Lambda表达式==========
    Map<String, Integer> items = new HashMap<>();
    items.put("A", 10);
    items.put("B", 20);
    items.put("C", 30);
    items.put("D", 40);
    items.put("E", 50);
    items.put("F", 60);
    items.forEach((k,v)->System.out.println("Item : " + k + " Count : " + v));
    items.forEach((k,v)->{
        System.out.println("Item : " + k + " Count : " + v);
        if("E".equals(k)){
            System.out.println("Hello E");
        }
    });
     ———————————————— 
    二遍历List: 
    ============Java8之前的方式==========

    List<String> items = new ArrayList<>(); items.add("A"); items.add("B"); items.add("C"); items.add("D"); items.add("E"); for(String item : items){ System.out.println(item); } ============forEach + Lambda表达式========== List<String> items = new ArrayList<>(); items.add("A"); items.add("B"); items.add("C"); items.add("D"); items.add("E"); //输出:A,B,C,D,E items.forEach(item->System.out.println(item)); //输出 : C items.forEach(item->{ if("C".equals(item)){ System.out.println(item); } });
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  • 原文地址:https://www.cnblogs.com/JonaLin/p/11395580.html
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