Java Android - 从 HashMap 中获取价值

Android - Get value from HashMap

提问by Paresh Mayani

I have tried to search on HashMap in Android, but getting problem:

我曾尝试在 Android 中搜索 HashMap，但遇到问题：

Consider this example:

考虑这个例子：

HashMap<String, String> meMap=new HashMap<String, String>();
meMap.put("Color1","Red");
meMap.put("Color2","Blue");
meMap.put("Color3","Green");
meMap.put("Color4","White");

now I want to iterate it and get the value of each color and want to display in "Toast". how do I display it?

现在我想迭代它并获取每种颜色的值并想在“Toast”中显示。我如何显示它？

采纳答案by Pentium10

Iterator myVeryOwnIterator = meMap.keySet().iterator();
while(myVeryOwnIterator.hasNext()) {
    String key=(String)myVeryOwnIterator.next();
    String value=(String)meMap.get(key);
    Toast.makeText(ctx, "Key: "+key+" Value: "+value, Toast.LENGTH_LONG).show();
}

回答by Suresh

HashMap<String, String> meMap=new HashMap<String, String>();
meMap.put("Color1","Red");
meMap.put("Color2","Blue");
meMap.put("Color3","Green");
meMap.put("Color4","White");
Iterator iterator = meMap.keySet().iterator();
while( iterator. hasNext() ){
    Toast.makeText(getBaseContext(), meMap.get(iterator.next().toString()), 
    Toast.LENGTH_SHORT).show();
}

回答by Nishant Shah

HashMap<String, String> meMap = new HashMap<String, String>();
meMap.put("Color1", "Red");
meMap.put("Color2", "Blue");
meMap.put("Color3", "Green");
meMap.put("Color4", "White");

Iterator myVeryOwnIterator = meMap.values().iterator();
while(myVeryOwnIterator.hasNext()) {
    Toast.makeText(getBaseContext(), myVeryOwnIterator.next(), Toast.LENGTH_SHORT).show();
}

回答by polygenelubricants

Here's a simple example to demonstrate Mapusage:

这是一个演示Map用法的简单示例：

Map<String, String> map = new HashMap<String, String>();
map.put("Color1","Red");
map.put("Color2","Blue");
map.put("Color3","Green");
map.put("Color4","White");

System.out.println(map);
// {Color4=White, Color3=Green, Color1=Red, Color2=Blue}        

System.out.println(map.get("Color2")); // Blue

System.out.println(map.keySet());
// [Color4, Color3, Color1, Color2]

for (Map.Entry<String,String> entry : map.entrySet()) {
    System.out.printf("%s -> %s%n", entry.getKey(), entry.getValue());
}
// Color4 -> White
// Color3 -> Green
// Color1 -> Red
// Color2 -> Blue

Note that the entries are iterated in arbitrary order. If you need a specific order, then you may consider e.g. LinkedHashMap

请注意，条目以任意顺序迭代。如果您需要特定的订单，那么您可以考虑例如LinkedHashMap

See also

也可以看看

• Effective Java 2nd Edition, Item 52: Refer to objects by their interfaces
• Java Tutorials/Collections- The Mapinterface
• Java Language Guide/The for-each loop

• Effective Java 2nd Edition，Item 52：通过接口引用对象
• Java教程/收藏-该Map接口
• Java 语言指南/for-each 循环

Related questions

相关问题

On iterating over entries:

在迭代条目时：

• Iterate Over Map
• iterating over and removing from a map
  • If you want to modify the map while iterating, you'd need to use its Iterator.

• 迭代地图
• 迭代并从地图中删除
  • 如果你想在迭代时修改地图，你需要使用它的Iterator.

On different Mapcharacteristics:

在不同的Map特性上：

• How to Maintain order of insertion using collections

• 如何使用集合维护插入顺序

---

---

On enum

在 enum

You may want to consider using an enumand EnumMapinstead of Map<String,String>.

您可能需要考虑使用enumandEnumMap而不是Map<String,String>。

See also

也可以看看

• Java Language Guide/Enums

• Java 语言指南/枚举

Related questions

相关问题

• Enumerations: Why? When?

• 枚举：为什么？什么时候？

回答by Ahmad

this work for me:

这对我有用：

HashMap<String, String> meMap=new HashMap<String, String>();
meMap.put("Color1","Red");
meMap.put("Color2","Blue");
meMap.put("Color3","Green");
meMap.put("Color4","White");

Iterator iterator = meMap.keySet().iterator();
while( iterator. hasNext() )
{
    Toast.makeText(getBaseContext(), meMap.get(iterator.next().toString()), 
    Toast.LENGTH_SHORT).show();
}

回答by Brian Stacks

This with no warnings!

这没有警告！

    HashMap<String, String> meMap=new HashMap<String, String>();
    meMap.put("Color1","Red");
    meMap.put("Color2","Blue");
    meMap.put("Color3","Green");
    meMap.put("Color4","White");

    for (Object o : meMap.keySet()) {
        Toast.makeText(getBaseContext(), meMap.get(o.toString()),
                Toast.LENGTH_SHORT).show();
    }

回答by Shetty Suresh Babu.

Note: If you know Key, use this code

注意：如果您知道 Key，请使用此代码

String value=meMap.get(key);

回答by Tony Augustine

for (Object key : meMap.keySet()) {
        String value=(String)meMap.get(key);
        Toast.makeText(ctx, "Key: "+key+" Value: "+value, Toast.LENGTH_LONG).show();
    }

回答by Syed Danish Haider

 Iterator iterator = meMap.keySet().iterator();
                while(iterator.hasNext() ){
                  //get key
                    String key=(String)iterator.next();
                    //toast value
                                           Toast.makeText(getBaseContext(),""+(String)meMap.get(key),Toast.LENGTH_SHORT).show();

                }