List demoList = new ArrayList<>();
demoList.add("618");
demoList.add("520");
for (int i = 0; i < demoList.size(); i++) {
System.out.println(demoList.get(i));
}
for (String str : demoList) {
System.out.println(str);
}
demoList.forEach(item -> {
System.out.println(item);
});
Iterator iterator = demoList.iterator();
while (iterator.hasNext()) {
String next = iterator.next();
System.out.println(next);
// 支持遍历删除
if ("520".equals(next)) {
iterator.remove();
}
}
demoList.stream().forEach(item -> {
System.out.println(item);
});
Map demoMap = new HashMap<>();
demoMap.put("张三", "520");
demoMap.put("李四", "618");
for (String key : demoMap.keySet()) {
System.out.println(key);
}
for (String value : demoMap.values()) {
System.out.println(value);
}
for (Map.Entry entry : demoMap.entrySet()) {
String key = entry.getKey();
String value = entry.getValue();
System.out.println("key:" + key + ",value:" + value);
}
idea快速生成entrySet循环操作,输入demoMap.entrySet().iter,点击iter即可。
快速生成entrySet循环
Set set = demoMap.keySet();
Iterator iterator = set.iterator();
while (iterator.hasNext()) {
String key = iterator.next();
String value = demoMap.get(key);
// 支持遍历删除
if ("张三".equals(key)) {
iterator.remove();
}
System.out.println("key:" + key + ",value:" + value);
}
demoMap.forEach((key,value)->{
System.out.println("key:" + key + ",value:" + value);
});
Set demoSet = new HashSet();
demoSet.add("520");
demoSet.add("618");
Iterator iterator = demoSet.iterator();
while (iterator.hasNext()) {
String next = iterator.next();
//遍历删除
if ("520".equals(next)) {
iterator.remove();
}
System.out.println(next);
}
for (String str : demoSet) {
System.out.println(str);
}
demoSet.forEach(item->{
System.out.println(item);
});
demoSet.stream().forEach(item->{
System.out.println(item);
});
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