Question

我有一个TextView，我希望得到一些特定行的文字，但是当我使用txt.getLayout.getLineStart(1)时，它会返回null并导致应用崩溃，这是什么原因？

TextView txt = (TextView)mRootView.findViewById(R.id.txt);
int start = txt.getLayout().getLineStart(1);
int end =  txt.getLayout().getLineEnd(1);
String first = txt.getText().subSequence(start,end).toString();

崩溃日志

E/AndroidRuntime: FATAL EXCEPTION: main
                  Process: com.sattva.animalsencyclopedia, PID: 11244
                  java.lang.NullPointerException
                      at com.sattva.animalsencyclopedia.fragments.FragmentInformation.onViewCreated(FragmentInformation.java:110)
                      at android.support.v4.app.FragmentManagerImpl.moveToState(FragmentManager.java:1086)
                      at android.support.v4.app.FragmentManagerImpl.moveToState(FragmentManager.java:1252)
                      at android.support.v4.app.BackStackRecord.run(BackStackRecord.java:738)
                      at android.support.v4.app.FragmentManagerImpl.execPendingActions(FragmentManager.java:1617)
                      at android.support.v4.app.FragmentManagerImpl$1.run(FragmentManager.java:517)
                      at android.os.Handler.handleCallback(Handler.java:808)
                      at android.os.Handler.dispatchMessage(Handler.java:103)
                      at android.os.Looper.loop(Looper.java:193)
                      at android.app.ActivityThread.main(ActivityThread.java:5333)
                      at java.lang.reflect.Method.invokeNative(Native Method)
                      at java.lang.reflect.Method.invoke(Method.java:515)
                      at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:829)
                      at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:645)
                      at dalvik.system.NativeStart.main(Native Method)

Answer 1

可能您没有以正确的方式使用findViewById()方法找到此视图。您正在使用片段，可能您有类似getActivity().findViewById()的内容。尝试使用onCreateView()方法执行类似view.findViewById()的操作，其中view是膨胀的结果。

正如@pskink在文档中提到的那样：returns Layout the Layout that is currently being used to display the text. This can be null if the text or width has recently changes.尝试在onStart或onCreate方法中调用此代码，但是您应该将txt作为类成员变量。

int start = txt.getLayout().getLineStart(1);
int end =  txt.getLayout().getLineEnd(1);
String first = txt.getText().subSequence(start,end).toString();

getLineStart（）总是为我的TextView返回null？

1 个答案: