我对Android很陌生，我正在尝试创建一个能够与Vex机器人大赛相匹配的应用程序。我有一个ViewPager每个团队都有片段，我有很多按钮可以增加和减少EditTexts中的数字。我为每个人创建了一个OnClickListener。在我引入SharedPreferences以将值传递给计算得分的活动之前，此代码正在运行。
片段代码（对不起，还有很多）：
package com.bearsandthings.vexskyrisescorer;
import android.content.Context;
import android.content.SharedPreferences;
import android.os.Bundle;
import android.support.v4.app.Fragment;
import android.view.LayoutInflater;
import android.view.View;
import android.view.View.OnClickListener;
import android.view.ViewGroup;
import android.widget.Button;
import android.widget.EditText;
public class BlueFragment extends Fragment {
public static int bafloorgoal, bapost, bapostowned, baskyrisebuilt, baskyrisecubes;
public static int bdfloorgoal, bdpost, bdpostowned, bdskyrisebuilt, bdskyrisecubes;
@Override
public View onCreateView(LayoutInflater inflater, ViewGroup container,
Bundle savedInstanceState) {
final View rootView = inflater.inflate(R.layout.fragment_blue, container, false);
//AUTONOMOUS
bafloorgoal = 0;
bapost = 0;
bapostowned = 0;
baskyrisebuilt = 0;
baskyrisecubes = 0;
bdfloorgoal = 0;
bdpost = 0;
bdpostowned = 0;
bdskyrisebuilt = 0;
bdskyrisecubes = 0;
final SharedPreferences prefs = this.getActivity().getSharedPreferences("com.bearsandthings.vexskyrisescorer", Context.MODE_PRIVATE);
prefs.edit().putInt("bafloorgoal", 0).apply();
prefs.edit().putInt("bapost", 0).apply();
prefs.edit().putInt("bapostowned", 0).apply();
prefs.edit().putInt("baskyrisebuilt", 0).apply();
prefs.edit().putInt("baskyrisecubes", 0).apply();
prefs.edit().putInt("bdfloorgoal", 0).apply();
prefs.edit().putInt("bdpost", 0).apply();
prefs.edit().putInt("bdpostowned", 0).apply();
prefs.edit().putInt("bdskyrisebuilt", 0).apply();
prefs.edit().putInt("bdskyrisecubes", 0).apply();
Button rAFloorGoalUp = (Button) rootView.findViewById(R.id.rAFloorGoalUp);
rAFloorGoalUp.setOnClickListener(new OnClickListener() {
@Override
public void onClick(View v) {
EditText rAFloorGoal = (EditText) rootView.findViewById(R.id.rAFloorGoal);
int testnum = Integer.valueOf(rAFloorGoal.getText().toString());
if (testnum < 22)
{
testnum += 1;
bafloorgoal = testnum;
prefs.edit().putInt("bafloorgoal",testnum).apply();
rAFloorGoal.setText(String.valueOf(testnum));
}
}
});
Button rAFloorGoalDown = (Button) rootView.findViewById(R.id.rAFloorGoalDn);
rAFloorGoalDown.setOnClickListener(new OnClickListener() {
@Override
public void onClick(View v) {
EditText rAFloorGoal = (EditText) rootView.findViewById(R.id.rAFloorGoal);
int testnum = Integer.parseInt(rAFloorGoal.getText().toString());
if (testnum > 0)
{
testnum -=1;
bafloorgoal = testnum;
prefs.edit().putInt("bafloorgoal",testnum).apply();
rAFloorGoal.setText(String.valueOf(testnum));
}
}
});
Button rAPostUp = (Button) rootView.findViewById(R.id.rAPostUp);
rAPostUp.setOnClickListener(new OnClickListener() {
@Override
public void onClick(View v) {
EditText rAPost = (EditText) rootView.findViewById(R.id.rAPost);
int testnum = Integer.parseInt(rAPost.getText().toString());
if (testnum < 22)
{
testnum +=1;
bapost = testnum;
prefs.edit().putInt("bapost",testnum).apply();
rAPost.setText(String.valueOf(testnum));
}
}
});
Button rAPostDn = (Button) rootView.findViewById(R.id.rAPostDn);
rAPostDn.setOnClickListener(new OnClickListener() {
@Override
public void onClick(View v) {
EditText rAPost = (EditText) rootView.findViewById(R.id.rAPost);
int testnum = Integer.parseInt(rAPost.getText().toString());
if (testnum > 0)
{
testnum -=1;
bapost = testnum;
prefs.edit().putInt("bapost", testnum).apply();
rAPost.setText(String.valueOf(testnum));
}
}
});
Button rAPostOwnedUp = (Button) rootView.findViewById(R.id.rAPostOwnedUp);
rAPostOwnedUp.setOnClickListener(new OnClickListener() {
@Override
public void onClick(View v) {
EditText rAPostOwned = (EditText) rootView.findViewById(R.id.rAPostOwned);
int testnum = Integer.parseInt(rAPostOwned.getText().toString());
if (testnum < 10)
{
testnum +=1;
bapostowned = testnum;
prefs.edit().putInt("bapost", testnum).apply();
rAPostOwned.setText(String.valueOf(testnum));
}
}
});
Button rAPostOwnedDn = (Button) rootView.findViewById(R.id.rAPostOwnedDn);
rAPostOwnedDn.setOnClickListener(new OnClickListener() {
@Override
public void onClick(View v) {
EditText rAPostOwned = (EditText) rootView.findViewById(R.id.rAPostOwned);
int testnum = Integer.parseInt(rAPostOwned.getText().toString());
if (testnum >0 )
{
testnum -=1;
bapostowned = testnum;
prefs.edit().putInt("bapostowned", testnum).apply();
rAPostOwned.setText(String.valueOf(testnum));
}
}
});
Button rASkyriseBuiltUp = (Button) rootView.findViewById(R.id.rASkyriseBuiltUp);
rASkyriseBuiltUp.setOnClickListener(new OnClickListener() {
@Override
public void onClick(View v) {
EditText rASkyriseBuilt = (EditText) rootView.findViewById(R.id.rASkyriseBuilt);
int testnum = Integer.parseInt(rASkyriseBuilt.getText().toString());
if (testnum < 7)
{
testnum += 1;
baskyrisebuilt = testnum;
prefs.edit().putInt("baskyrisebuilt", testnum).apply();
rASkyriseBuilt.setText(String.valueOf(testnum));
}
}
});
Button rASkyriseBuiltDn = (Button) rootView.findViewById(R.id.rASkyriseBuiltDn);
rASkyriseBuiltDn.setOnClickListener(new OnClickListener() {
@Override
public void onClick(View v) {
EditText rASkyriseBuilt = (EditText) rootView.findViewById(R.id.rASkyriseBuilt);
int testnum = Integer.parseInt(rASkyriseBuilt.getText().toString());
if (testnum > 0)
{
testnum -= 1;
baskyrisebuilt = testnum;
prefs.edit().putInt("baskyrisebuilt", testnum).apply();
rASkyriseBuilt.setText(String.valueOf(testnum));
}
}
});
Button rASkyriseCubesUp = (Button) rootView.findViewById(R.id.rASkyriseCubesUp);
rASkyriseCubesUp.setOnClickListener(new OnClickListener() {
@Override
public void onClick(View v) {
EditText rASkyriseCubes = (EditText) rootView.findViewById(R.id.rASkyriseCubes);
int testnum = Integer.parseInt(rASkyriseCubes.getText().toString());
if (testnum < 22)
{
testnum +=1;
baskyrisecubes = testnum;
prefs.edit().putInt("baskyrisecubes", testnum).apply();
rASkyriseCubes.setText(String.valueOf(testnum));
}
}
});
Button rASkyriseCubesDn = (Button) rootView.findViewById(R.id.rASkyriseCubesDn);
rASkyriseCubesDn.setOnClickListener(new OnClickListener() {
@Override
public void onClick(View v) {
EditText rASkyriseCubes = (EditText) rootView.findViewById(R.id.rASkyriseCubes);
int testnum = Integer.parseInt(rASkyriseCubes.getText().toString());
if (testnum > 0)
{
testnum -=1;
baskyrisecubes = testnum;
prefs.edit().putInt("baskyrisecubes", testnum).apply();
rASkyriseCubes.setText(String.valueOf(testnum));
}
}
});
// DRIVER CONTROL
Button rDFloorGoalUp = (Button) rootView.findViewById(R.id.rDFloorGoalUp);
rDFloorGoalUp.setOnClickListener(new OnClickListener() {
@Override
public void onClick(View v) {
EditText rDFloorGoal = (EditText) rootView.findViewById(R.id.rDFloorGoal);
int testnum = Integer.valueOf(rDFloorGoal.getText().toString());
if (testnum < 22)
{
testnum += 1;
bdfloorgoal = testnum;
prefs.edit().putInt("bdfloorgoal", testnum).apply();
rDFloorGoal.setText(String.valueOf(testnum));
}
}
});
Button rDFloorGoalDown = (Button) rootView.findViewById(R.id.rDFloorGoalDn);
rDFloorGoalDown.setOnClickListener(new OnClickListener() {
@Override
public void onClick(View v) {
EditText rDFloorGoal = (EditText) rootView.findViewById(R.id.rDFloorGoal);
int testnum = Integer.parseInt(rDFloorGoal.getText().toString());
if (testnum > 0)
{
testnum -=1;
bdfloorgoal = testnum;
prefs.edit().putInt("bdfloorgoal", testnum).apply();
rDFloorGoal.setText(String.valueOf(testnum));
}
}
});
Button rDPostUp = (Button) rootView.findViewById(R.id.rDPostUp);
rDPostUp.setOnClickListener(new OnClickListener() {
@Override
public void onClick(View v) {
EditText rDPost = (EditText) rootView.findViewById(R.id.rDPost);
int testnum = Integer.parseInt(rDPost.getText().toString());
if (testnum < 22)
{
testnum +=1;
bdpost = testnum;
prefs.edit().putInt("bdpost", testnum).apply();
rDPost.setText(String.valueOf(testnum));
}
}
});
Button rDPostDn = (Button) rootView.findViewById(R.id.rDPostDn);
rDPostDn.setOnClickListener(new OnClickListener() {
@Override
public void onClick(View v) {
EditText rDPost = (EditText) rootView.findViewById(R.id.rDPost);
int testnum = Integer.parseInt(rDPost.getText().toString());
if (testnum > 0)
{
testnum -=1;
bdpost = testnum;
prefs.edit().putInt("bdpost", testnum).apply();
rDPost.setText(String.valueOf(testnum));
}
}
});
Button rDPostOwnedUp = (Button) rootView.findViewById(R.id.rDPostOwnedUp);
rDPostOwnedUp.setOnClickListener(new OnClickListener() {
@Override
public void onClick(View v) {
EditText rDPostOwned = (EditText) rootView.findViewById(R.id.rDPostOwned);
int testnum = Integer.parseInt(rDPostOwned.getText().toString());
if (testnum < 10)
{
testnum +=1;
bdpostowned = testnum;
prefs.edit().putInt("bdpostowned", testnum).apply();
rDPostOwned.setText(String.valueOf(testnum));
}
}
});
Button rDPostOwnedDn = (Button) rootView.findViewById(R.id.rDPostOwnedDn);
rDPostOwnedDn.setOnClickListener(new OnClickListener() {
@Override
public void onClick(View v) {
EditText rDPostOwned = (EditText) rootView.findViewById(R.id.rDPostOwned);
int testnum = Integer.parseInt(rDPostOwned.getText().toString());
if (testnum >0 )
{
testnum -=1;
bdpostowned = testnum;
prefs.edit().putInt("bdpostowned", testnum).apply();
rDPostOwned.setText(String.valueOf(testnum));
}
}
});
Button rDSkyriseBuiltUp = (Button) rootView.findViewById(R.id.rDSkyriseBuiltUp);
rDSkyriseBuiltUp.setOnClickListener(new OnClickListener() {
@Override
public void onClick(View v) {
EditText rDSkyriseBuilt = (EditText) rootView.findViewById(R.id.rDSkyriseBuilt);
int testnum = Integer.parseInt(rDSkyriseBuilt.getText().toString());
if (testnum < 7)
{
testnum += 1;
bdskyrisebuilt = testnum;
prefs.edit().putInt("bdskyrisebuilt", testnum).apply();
rDSkyriseBuilt.setText(String.valueOf(testnum));
}
}
});
Button rDSkyriseBuiltDn = (Button) rootView.findViewById(R.id.rDSkyriseBuiltDn);
rDSkyriseBuiltDn.setOnClickListener(new OnClickListener() {
@Override
public void onClick(View v) {
EditText rDSkyriseBuilt = (EditText) rootView.findViewById(R.id.rDSkyriseBuilt);
int testnum = Integer.parseInt(rDSkyriseBuilt.getText().toString());
if (testnum > 0)
{
testnum -= 1;
bdskyrisebuilt = testnum;
prefs.edit().putInt("bdskyrisebuilt", testnum).apply();
rDSkyriseBuilt.setText(String.valueOf(testnum));
}
}
});
Button rDSkyriseCubesUp = (Button) rootView.findViewById(R.id.rDSkyriseCubesUp);
rDSkyriseCubesUp.setOnClickListener(new OnClickListener() {
@Override
public void onClick(View v) {
EditText rDSkyriseCubes = (EditText) rootView.findViewById(R.id.rDSkyriseCubes);
int testnum = Integer.parseInt(rDSkyriseCubes.getText().toString());
if (testnum < 22)
{
testnum +=1;
bdskyrisecubes = testnum;
prefs.edit().putInt("bdskyrisecubes", testnum).apply();
rDSkyriseCubes.setText(String.valueOf(testnum));
}
}
});
Button rDSkyriseCubesDn = (Button) rootView.findViewById(R.id.rDSkyriseCubesDn);
rDSkyriseCubesDn.setOnClickListener(new OnClickListener() {
@Override
public void onClick(View v) {
EditText rDSkyriseCubes = (EditText) rootView.findViewById(R.id.rDSkyriseCubes);
int testnum = Integer.parseInt(rDSkyriseCubes.getText().toString());
if (testnum > 0)
{
testnum -=1;
bdskyrisecubes = testnum;
prefs.edit().putInt("bdskyrisecubes", testnum).apply();
rDSkyriseCubes.setText(String.valueOf(testnum));
}
}
});
return rootView;
}
}
LogCat：
05-30 22:04:05.827: E/AndroidRuntime(16083): FATAL EXCEPTION: main
05-30 22:04:05.827: E/AndroidRuntime(16083): java.lang.NullPointerException
05-30 22:04:05.827: E/AndroidRuntime(16083): at com.bearsandthings.vexskyrisescorer.BlueFragment.onCreateView(BlueFragment.java:48)
05-30 22:04:05.827: E/AndroidRuntime(16083): at android.support.v4.app.Fragment.performCreateView(Fragment.java:1500)
05-30 22:04:05.827: E/AndroidRuntime(16083): at android.support.v4.app.FragmentManagerImpl.moveToState(FragmentManager.java:927)
05-30 22:04:05.827: E/AndroidRuntime(16083): at android.support.v4.app.FragmentManagerImpl.moveToState(FragmentManager.java:1104)
05-30 22:04:05.827: E/AndroidRuntime(16083): at android.support.v4.app.BackStackRecord.run(BackStackRecord.java:682)
05-30 22:04:05.827: E/AndroidRuntime(16083): at android.support.v4.app.FragmentManagerImpl.execPendingActions(FragmentManager.java:1467)
05-30 22:04:05.827: E/AndroidRuntime(16083): at android.support.v4.app.FragmentManagerImpl.executePendingTransactions(FragmentManager.java:472)
05-30 22:04:05.827: E/AndroidRuntime(16083): at android.support.v4.app.FragmentPagerAdapter.finishUpdate(FragmentPagerAdapter.java:141)
05-30 22:04:05.827: E/AndroidRuntime(16083): at android.support.v4.view.ViewPager.populate(ViewPager.java:1068)
05-30 22:04:05.827: E/AndroidRuntime(16083): at android.support.v4.view.ViewPager.populate(ViewPager.java:914)
05-30 22:04:05.827: E/AndroidRuntime(16083): at android.support.v4.view.ViewPager.onMeasure(ViewPager.java:1436)
05-30 22:04:05.827: E/AndroidRuntime(16083): at android.view.View.measure(View.java:12729)
05-30 22:04:05.827: E/AndroidRuntime(16083): at android.view.ViewGroup.measureChildWithMargins(ViewGroup.java:4706)
05-30 22:04:05.827: E/AndroidRuntime(16083): at android.widget.FrameLayout.onMeasure(FrameLayout.java:293)
05-30 22:04:05.827: E/AndroidRuntime(16083): at android.view.View.measure(View.java:12729)
05-30 22:04:05.827: E/AndroidRuntime(16083): at android.widget.LinearLayout.measureVertical(LinearLayout.java:812)
05-30 22:04:05.827: E/AndroidRuntime(16083): at android.widget.LinearLayout.onMeasure(LinearLayout.java:553)
05-30 22:04:05.827: E/AndroidRuntime(16083): at android.view.View.measure(View.java:12729)
05-30 22:04:05.827: E/AndroidRuntime(16083): at android.view.ViewGroup.measureChildWithMargins(ViewGroup.java:4706)
05-30 22:04:05.827: E/AndroidRuntime(16083): at android.widget.FrameLayout.onMeasure(FrameLayout.java:293)
05-30 22:04:05.827: E/AndroidRuntime(16083): at com.android.internal.policy.impl.PhoneWindow$DecorView.onMeasure(PhoneWindow.java:2098)
05-30 22:04:05.827: E/AndroidRuntime(16083): at android.view.View.measure(View.java:12729)
05-30 22:04:05.827: E/AndroidRuntime(16083): at android.view.ViewRootImpl.performTraversals(ViewRootImpl.java:1064)
05-30 22:04:05.827: E/AndroidRuntime(16083): at android.view.ViewRootImpl.handleMessage(ViewRootImpl.java:2453)
05-30 22:04:05.827: E/AndroidRuntime(16083): at android.os.Handler.dispatchMessage(Handler.java:99)
05-30 22:04:05.827: E/AndroidRuntime(16083): at android.os.Looper.loop(Looper.java:137)
05-30 22:04:05.827: E/AndroidRuntime(16083): at android.app.ActivityThread.main(ActivityThread.java:4429)
05-30 22:04:05.827: E/AndroidRuntime(16083): at java.lang.reflect.Method.invokeNative(Native Method)
05-30 22:04:05.827: E/AndroidRuntime(16083): at java.lang.reflect.Method.invoke(Method.java:511)
05-30 22:04:05.827: E/AndroidRuntime(16083): at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:3151)
05-30 22:04:05.827: E/AndroidRuntime(16083): at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:2918)
05-30 22:04:05.827: E/AndroidRuntime(16083): at dalvik.system.NativeStart.main(Native Method)
答案 0 :(得分：1)
打开fragment_blue.xml布局。您需要在此文件中声明标识为Button的{{1}}。
当它不是
时rAFloorGoalUp将被分配Button rAFloorGoalUp = (Button) rootView.findViewById(R.id.rAFloorGoalUp);
和
null会引发rAFloorGoalUp.setOnClickListener(...)
错误。