关于Java:Map，如何同时打印”key string”和”value string”

Map<String, String>, how to print both the “key string” and “value string” together

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我是Java新手，正在学习地图的概念。

我想出了下面的代码。但是，我想同时打印出"key string"和"value string"。

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ProcessBuilder pb1 = new ProcessBuilder();
Map<String, String> mss1 = pb1.environment();
System.out.println(mss1.size());

for (String key: mss1.keySet()){
System.out.println(key);
}

我只能找到只打印"密钥字符串"的方法。

相关讨论

实现这一目标的方法多种多样。这里有三个。

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Map<String, String> map = new HashMap<String, String>();
map.put("key1","value1");
map.put("key2","value2");
map.put("key3","value3");

System.out.println("using entrySet and toString");
for (Entry<String, String> entry : map.entrySet()) {
System.out.println(entry);
}
System.out.println();

System.out.println("using entrySet and manual string creation");
for (Entry<String, String> entry : map.entrySet()) {
System.out.println(entry.getKey() +"=" + entry.getValue());
}
System.out.println();

System.out.println("using keySet");
for (String key : map.keySet()) {
System.out.println(key +"=" + map.get(key));
}
System.out.println();

产量

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using entrySet and toString
key1=value1
key2=value2
key3=value3

using entrySet and manual string creation
key1=value1
key2=value2
key3=value3

using keySet
key1=value1
key2=value2
key3=value3

在循环内部，您有一个键，可以使用它从Map中检索值：

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for (String key: mss1.keySet()) {
System.out.println(key +":" + mss1.get(key));
}

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final Map<String, String> mss1 = new ProcessBuilder().environment();
mss1.entrySet()
.stream()
//depending on how you want to join K and V use different delimiter
.map(entry ->
String.join(":", entry.getKey(),entry.getValue()))
.forEach(System.out::println);