List分组并根据某个字段取最大的一条数据
TestObj testObj1 = new TestObj(); testObj1.setJob("ceshi1"); testObj1.setNum(4); TestObj testObj2 = new TestObj(); testObj2.setJob("ceshi1"); testObj2.setNum(2); TestObj testObj3 = new TestObj(); testObj3.setJob("ceshi1"); testObj3.setNum(1); TestObj testObj4 = new TestObj(); testObj4.setJob("ceshi2"); testObj4.setNum(2); TestObj testObj5 = new TestObj(); testObj5.setJob("ceshi2"); testObj5.setNum(1); List<TestObj> list = new ArrayList<>(); list.add(testObj1); list.add(testObj2); list.add(testObj3); list.add(testObj4); list.add(testObj5); Map<String, TestObj> maxAgePerson =list.stream() .collect(Collectors.groupingBy(TestObj::getJob, Collectors.collectingAndThen( Collectors.maxBy(Comparator.comparingInt(TestObj::getNum)), Optional::get))); System.out.println(maxAgePerson.toString());
结果:
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