我最近发布了一个问题来解决我遇到的一些运行时错误，并且效果很好。但是，我仍然有一些更多，我不知道为什么我有一个似乎是一个nullpointer错误指向我的setOnClickListener按钮。我是Stack Overflow的新手，我仍然无法格式化代码和错误。
这是java文件：
import android.graphics.Color;
import android.os.Bundle;
import android.support.v4.app.Fragment;
import android.view.LayoutInflater;
import android.view.View;
import android.view.ViewGroup;
import android.widget.Button;
import android.widget.EditText;
import android.widget.TextView;
public class OppositeFragment extends Fragment {
private static TextView sOppositeView;
private Button mSubmit;
private int mRedValue, mGreenValue, mBlueValue;
private EditText mRedSelect, mGreenSelect, mBlueSelect;
public View onCreateView(LayoutInflater inflater, ViewGroup container, Bundle savedInstanceState)
{
View view = inflater.inflate(R.layout.text_fragment, container, false);
sOppositeView = (TextView) view.findViewById(R.id.textView1);
mRedSelect = (EditText)view.findViewById(R.id.redValue);
mGreenSelect = (EditText)view.findViewById(R.id.greenValue);
mBlueSelect = (EditText)view.findViewById(R.id.blueValue);
mSubmit = (Button) view.findViewById(R.id.submitButton);
mSubmit.setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View v) {
try {
mRedValue = Integer.parseInt(mRedSelect.getText().toString());
mGreenValue = Integer.parseInt(mGreenSelect.getText().toString());
mBlueValue = Integer.parseInt(mBlueSelect.getText().toString());
sOppositeView.setTextColor(Color.rgb(mRedValue, mGreenValue, mBlueValue));
} catch (NumberFormatException nfe) { // do nothing
}
}
});
return view;
}
public void changeTextProperties(int fontsize, String text)
{
sOppositeView.setTextSize(100-fontsize);
sOppositeView.setText(text);
}
}
第34行是mSubmit.setOnclickListner行。
这是片段的xml：
<?xml version="1.0" encoding="utf-8"?>
<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
android:layout_width="match_parent"
android:layout_height="match_parent" >
<EditText
android:id="@+id/blueValue"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_centerHorizontal="true"
android:layout_below="@+id/greenValue"
android:hint="@string/blue_hint"
android:ems="10"
android:inputType="number" />
<EditText
android:id="@+id/greenValue"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_centerHorizontal="true"
android:layout_below="@+id/redValue"
android:ems="10"
android:hint="@string/green_hint"
android:inputType="number" />
<TextView
android:id="@+id/oppositeTextView"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_alignParentTop="true"
android:layout_centerHorizontal="true"
android:text="@string/text_label_two" />
<EditText
android:id="@+id/redValue"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_alignLeft="@+id/greenValue"
android:layout_below="@+id/oppositeTextView"
android:ems="10"
android:hint="@string/red_hint"
android:inputType="number" />
<Button
android:id="@+id/submitButton"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_below="@+id/blueValue"
android:layout_centerHorizontal="true"
android:text="@string/color_change_label" />
</RelativeLayout>
最后，这是logcat：
11-16 22:34:02.239: E/AndroidRuntime(1188): FATAL EXCEPTION: main
11-16 22:34:02.239: E/AndroidRuntime(1188): Process: meng.jerry.fragmentexample, PID: 1188
11-16 22:34:02.239: E/AndroidRuntime(1188): java.lang.RuntimeException: Unable to start activity ComponentInfo{meng.jerry.fragmentexample/meng.jerry.fragmentexample.FragmentExampleActivity}: android.view.InflateException: Binary XML file line #28: Error inflating class fragment
11-16 22:34:02.239: E/AndroidRuntime(1188): at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2195)
11-16 22:34:02.239: E/AndroidRuntime(1188): at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2245)
11-16 22:34:02.239: E/AndroidRuntime(1188): at android.app.ActivityThread.access$800(ActivityThread.java:135)
11-16 22:34:02.239: E/AndroidRuntime(1188): at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1196)
11-16 22:34:02.239: E/AndroidRuntime(1188): at android.os.Handler.dispatchMessage(Handler.java:102)
11-16 22:34:02.239: E/AndroidRuntime(1188): at android.os.Looper.loop(Looper.java:136)
11-16 22:34:02.239: E/AndroidRuntime(1188): at android.app.ActivityThread.main(ActivityThread.java:5017)
11-16 22:34:02.239: E/AndroidRuntime(1188): at java.lang.reflect.Method.invokeNative(Native Method)
11-16 22:34:02.239: E/AndroidRuntime(1188): at java.lang.reflect.Method.invoke(Method.java:515)
11-16 22:34:02.239: E/AndroidRuntime(1188): at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:779)
11-16 22:34:02.239: E/AndroidRuntime(1188): at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:595)
11-16 22:34:02.239: E/AndroidRuntime(1188): at dalvik.system.NativeStart.main(Native Method)
11-16 22:34:02.239: E/AndroidRuntime(1188): Caused by: android.view.InflateException: Binary XML file line #28: Error inflating class fragment
11-16 22:34:02.239: E/AndroidRuntime(1188): at android.view.LayoutInflater.createViewFromTag(LayoutInflater.java:713)
11-16 22:34:02.239: E/AndroidRuntime(1188): at android.view.LayoutInflater.rInflate(LayoutInflater.java:755)
11-16 22:34:02.239: E/AndroidRuntime(1188): at android.view.LayoutInflater.inflate(LayoutInflater.java:492)
11-16 22:34:02.239: E/AndroidRuntime(1188): at android.view.LayoutInflater.inflate(LayoutInflater.java:397)
11-16 22:34:02.239: E/AndroidRuntime(1188): at android.view.LayoutInflater.inflate(LayoutInflater.java:353)
11-16 22:34:02.239: E/AndroidRuntime(1188): at com.android.internal.policy.impl.PhoneWindow.setContentView(PhoneWindow.java:290)
11-16 22:34:02.239: E/AndroidRuntime(1188): at android.app.Activity.setContentView(Activity.java:1929)
11-16 22:34:02.239: E/AndroidRuntime(1188): at meng.jerry.fragmentexample.FragmentExampleActivity.onCreate(FragmentExampleActivity.java:19)
11-16 22:34:02.239: E/AndroidRuntime(1188): at android.app.Activity.performCreate(Activity.java:5231)
11-16 22:34:02.239: E/AndroidRuntime(1188): at android.app.Instrumentation.callActivityOnCreate(Instrumentation.java:1087)
11-16 22:34:02.239: E/AndroidRuntime(1188): at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2159)
11-16 22:34:02.239: E/AndroidRuntime(1188): ... 11 more
11-16 22:34:02.239: E/AndroidRuntime(1188): Caused by: java.lang.NullPointerException
11-16 22:34:02.239: E/AndroidRuntime(1188): at meng.jerry.fragmentexample.OppositeFragment.onCreateView(OppositeFragment.java:35)
11-16 22:34:02.239: E/AndroidRuntime(1188): at android.support.v4.app.Fragment.performCreateView(Fragment.java:1504)
11-16 22:34:02.239: E/AndroidRuntime(1188): at android.support.v4.app.FragmentManagerImpl.moveToState(FragmentManager.java:915)
11-16 22:34:02.239: E/AndroidRuntime(1188): at android.support.v4.app.FragmentManagerImpl.moveToState(FragmentManager.java:1099)
11-16 22:34:02.239: E/AndroidRuntime(1188): at android.support.v4.app.FragmentManagerImpl.addFragment(FragmentManager.java:1201)
11-16 22:34:02.239: E/AndroidRuntime(1188): at android.support.v4.app.FragmentActivity.onCreateView(FragmentActivity.java:292)
11-16 22:34:02.239: E/AndroidRuntime(1188): at android.view.LayoutInflater.createViewFromTag(LayoutInflater.java:685)
11-16 22:34:02.239: E/AndroidRuntime(1188): ... 21 more
这些错误一直困扰着我好几个小时。此外，我为糟糕的格式道歉。
此外，这是主要活动的代码：
import android.os.Bundle;
import android.support.v4.app.FragmentActivity;
import android.view.Menu;
public class FragmentExampleActivity extends FragmentActivity implements ToolbarFragment.ToolbarListener {
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_fragment_example);
}
@Override
public void onButtonClick(int fontsize, String text)
{
//instantiates the new fragments as well as start editing the text
TextFragment textFragment = (TextFragment) getSupportFragmentManager()
.findFragmentById(R.id.text_fragment);
textFragment.changeTextProperties(fontsize, text);
OppositeFragment oppositeFragment=(OppositeFragment) getSupportFragmentManager()
.findFragmentById(R.id.opposite_fragment);
oppositeFragment.changeTextProperties(fontsize, text);
}
@Override
public boolean onCreateOptionsMenu(Menu menu) {
// Inflate the menu; this adds items to the action bar if it is present.
getMenuInflater().inflate(R.menu.fragment_example, menu);
return true;
}
}
那个xml：
<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:tools="http://schemas.android.com/tools"
android:layout_width="match_parent"
android:layout_height="match_parent"
tools:context=".FragmentExampleActivity" >
<!-- Fragment that contains the toolbar -->
<fragment
android:id="@+id/toolbar_fragment"
android:name="meng.jerry.fragmentexample.ToolbarFragment"
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:layout_alignParentLeft="true"
android:layout_alignParentStart="true"
android:layout_alignParentTop="true"
tools:layout="@layout/toolbar_fragment"/>
<!-- Fragment that displays the text -->
<fragment
android:id="@+id/text_fragment"
android:name="meng.jerry.fragmentexample.TextFragment"
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:layout_alignParentLeft="true"
android:layout_alignParentStart="true"
android:layout_below="@+id/toolbar_fragment"
android:layout_marginTop="40dp"
tools:layout="@layout/text_fragment" />
<!-- Fragment that displays the text in reverse -->
<fragment
android:id="@+id/opposite_fragment"
android:name="meng.jerry.fragmentexample.OppositeFragment"
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:layout_alignParentLeft="true"
android:layout_alignParentStart="true"
android:layout_below="@+id/text_fragment"
android:layout_marginTop="16dp"
tools:layout="@layout/opposite_fragment" />
</RelativeLayout>
答案 0 :(得分：1)
在这里，您使用的是TextView
的错误ID sOppositeView = (TextView) view.findViewById(R.id.textView1);
实际上你的XML包含这个
android:id="@+id/oppositeTextView"