1、List遍历
List<String> items = new ArrayList<>(); items.add("A"); items.add("B"); items.add("C"); items.add("D"); items.add("E"); //lambda //Output : A,B,C,D,E items.forEach(item->System.out.println(item)); //Output : C items.forEach(item->{ if("C".equals(item)){ System.out.println(item); } }); //method reference //Output : A,B,C,D,E items.forEach(System.out::println); //Stream and filter //Output : B items.stream() .filter(s->s.contains("B")) .forEach(System.out::println);
2、Map遍历
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"); } });
3、遍历enum
public enum ColumnTypeEnums { INTEGER("int", "Integer"), VARCHAR("varchar", "String"), DATE("date", "java.util.Date"), TIME("datetime", "java.util.Date"), NUMERIC("numeric", "java.math.BigDecimal"), DECIMAL("decimal", "java.math.BigDecimal"), TINYINT("tinyint", "byte"), SMALLINT("smallint", "short"), BIGINT("bigint", "long"), FLOAT("float", "double"), DOUBLE("double", "double"), CHAR("char", "String"); private String pdm; private String java; public void setPdm(String pdm) { this.pdm = pdm; } public void setJava(String java) { this.java = java; } public static ColumnTypeEnums getByPdm(String pdm) { ColumnTypeEnums e = null; for (ColumnTypeEnums en : ColumnTypeEnums.values()) { if (en.getPdm().equals(pdm)) { e = en; } } return e; } public static void main(String[] args) { ColumnTypeEnums e = ColumnTypeEnums.getByPdm("tinyint"); Console.log("==============="); Console.log("{},{},{}", e.name(), e.getPdm(), e.getJava()); } }