在Android中将ArrayList转换为String数组 [英] Convert ArrayList to String array in Android
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问题描述
我有一个包含 [ann,john] 形式的值的 ArrayList.我想将此 ArrayList 转换为 {"ann","john"} 形式的 String 数组.
I have a ArrayList that contains values in the form [ann,john]. I want to convert this ArrayList into a String array in the form {"ann","john"}.
我该怎么做?
我的安卓代码:
final Button markabsent = (Button) findViewById(R.id.Button02);
markabsent.setOnClickListener(new View.OnClickListener() {
public void onClick(View v) {
// Perform action on click
Toast.makeText(display.this,"You have marked the students absent",Toast.LENGTH_SHORT).show();
SparseBooleanArray checkedabsent = lView.getCheckedItemPositions();
for (int i = 0; i < arr2.length; i++)
{
if (checkedabsent.get(i))
{
items2.add(arr2[i]);
System.out.println(items2);
}
}
Log.d("", "items:");
for (String string : items2)
{
Log.d("string is", string);
}
}
});
我的 Logcat:
11-10 21:44:00.414: INFO/System.out(2316): [ann, john, ann]
11-10 21:44:00.414: DEBUG/(2316): items:
11-10 21:44:00.414: DEBUG/string is(2316): ann
11-10 21:44:00.414: DEBUG/string is(2316): john
我尝试做答案中提到的所有事情,但我的 logcat 似乎没有改善
I tried doing everything mentioned in the answers but my logcat just doesn't seem to imrove
这是一个例外:
11-10 22:14:20.855: INFO/System.out(3322): [Ljava.lang.String;@44eb6ff0
11-10 22:16:38.186: ERROR/AndroidRuntime(3411): FATAL EXCEPTION: main
11-10 22:16:38.186: ERROR/AndroidRuntime(3411): java.lang.ClassCastException: [Ljava.lang.Object;
11-10 22:16:38.186: ERROR/AndroidRuntime(3411): at com.example.display$2.onClick(display.java:124)
11-10 22:16:38.186: ERROR/AndroidRuntime(3411): at android.view.View.performClick(View.java:2408)
11-10 22:16:38.186: ERROR/AndroidRuntime(3411): at android.view.View$PerformClick.run(View.java:8816)
11-10 22:16:38.186: ERROR/AndroidRuntime(3411): at android.os.Handler.handleCallback(Handler.java:587)
还有一个:
11-10 22:14:20.875: DEBUG/string is(3322): ann
11-10 22:14:20.875: INFO/System.out(3322): [Ljava.lang.String;@44eb7720
11-10 22:14:20.875: INFO/System.out(3322): [Ljava.lang.String;@44eb7720
11-10 22:14:20.885: INFO/System.out(3322): [Ljava.lang.String;@44eb7720
11-10 22:14:20.895: DEBUG/string is(3322): john
11-10 22:14:20.895: INFO/System.out(3322): [Ljava.lang.String;@44eb7de8
11-10 22:16:38.186: ERROR/AndroidRuntime(3411): at com.example.display$2.onClick(display.java:124)
推荐答案
使用toArray()"方法
Use the method "toArray()"
ArrayList<String> mStringList= new ArrayList<String>();
mStringList.add("ann");
mStringList.add("john");
Object[] mStringArray = mStringList.toArray();
for(int i = 0; i < mStringArray.length ; i++){
Log.d("string is",(String)mStringArray[i]);
}
或者你可以这样做:(在其他答案中提到)
or you can do it like this: (mentioned in other answers)
ArrayList<String> mStringList= new ArrayList<String>();
mStringList.add("ann");
mStringList.add("john");
String[] mStringArray = new String[mStringList.size()];
mStringArray = mStringList.toArray(mStringArray);
for(int i = 0; i < mStringArray.length ; i++){
Log.d("string is",(String)mStringArray[i]);
}
http://developer.android.com/reference/java/util/ArrayList.html#toArray()
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