我不确定如何正确构建这个包裹;当我尝试从null添加包裹的对象时，我将返回MainActivity。
发送intent：
public void onClick(View v) {
Intent myIntent = new Intent(listaddactivity.this,
MainActivity.class);
myIntent.putExtra(
"custom_object",
new listControlObject(namefield.getText().toString(),
iterator, temperatureFrag.getCurrentTempType(), Integer
.valueOf(powerPercent.getText()
.toString()), Integer
.valueOf(frequencyField.getText()
.toString()),
temperatureFrag.temperaturenumberpicker
.getValue(), cycleFrag.startTimeField
.getCurrentHour(),
cycleFrag.startTimeField.getCurrentMinute(),
cycleFrag.cycleDatePicker.getDayOfMonth(),
cycleFrag.cycleDatePicker.getMonth(), Integer
.valueOf(cycleFrag.numberOfCyclesField
.getText().toString()))); // Optional
// parameters
startActivity(myIntent);
Log.d("LISTACTIVITY", "Intent successfully passed!");
iterator++;
}
});
}
接收activity：
public class MainActivity extends FragmentActivity implements
ActionBar.TabListener {
String TAG;
HomeFragment homeFragment;
cycleviewfragment cyclefragment;
SectionsPagerAdapter mSectionsPagerAdapter;
/**
* The {@linkCustomViewPager} that will host the section contents.
*/
CustomViewPager mViewPager;
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
// Set up the action bar.
final ActionBar actionBar = getActionBar();
actionBar.setNavigationMode(ActionBar.NAVIGATION_MODE_TABS);
homeFragment = new HomeFragment();
cyclefragment = new cycleviewfragment();
// Create the adapter that will return a fragment for each of the three
// primary sections of the app.
mSectionsPagerAdapter = new SectionsPagerAdapter(
getSupportFragmentManager());
// Set up theCustomViewPager with the sections adapter.
mViewPager = (CustomViewPager) findViewById(R.id.pager);
mViewPager.setAdapter(mSectionsPagerAdapter);
mViewPager.setPagingEnabled(false);
// When swiping between different sections, select the corresponding
// tab. We can also use ActionBar.Tab#select() to do this if we have
// a reference to the Tab.
mViewPager
.setOnPageChangeListener(new CustomViewPager.SimpleOnPageChangeListener() {
@Override
public void onPageSelected(int position) {
actionBar.setSelectedNavigationItem(position);
}
});
// For each of the sections in the app, add a tab to the action bar.
for (int i = 0; i < mSectionsPagerAdapter.getCount(); i++) {
// Create a tab with text corresponding to the page title defined by
// the adapter. Also specify this Activity object, which implements
// the TabListener interface, as the callback (listener) for when
// this tab is selected.
actionBar.addTab(actionBar.newTab()
.setText(mSectionsPagerAdapter.getPageTitle(i))
.setTabListener(this));
}
processNewIntent(getIntent());
}
@Override
protected void onNewIntent(Intent intent) {
super.onNewIntent(intent);
processNewIntent(intent);
}
private void processNewIntent(Intent intent) {
Log.v("TEST", "METHOD CALLED TEST");
if (intent.hasExtra("custom_object")) {
cyclefragment.a1.add((listControlObject) intent.getParcelableExtra("custom_object"));
cyclefragment.adapter.notifyDataSetChanged();
}
}
发送intent时，我是否错误地实施了包裹？我的processNewIntent是否有理由给我NullPointerException？
我猜测有一种特定的方法可以构建一个包裹，并通过我没有正确实施的意图传递它，但我找不到任何好的资源。
Logcat：
03-24 01:13:30.846: E/Trace(7974): error opening trace file: No such file or directory (2)
03-24 01:13:44.374: E/AndroidRuntime(7974): FATAL EXCEPTION: main
03-24 01:13:44.374: E/AndroidRuntime(7974): java.lang.NullPointerException
03-24 01:13:44.374: E/AndroidRuntime(7974): at com.nanospark.upcdemo.listaddactivity$1.onClick(listaddactivity.java:72)
03-24 01:13:44.374: E/AndroidRuntime(7974): at android.view.View.performClick(View.java:4091)
03-24 01:13:44.374: E/AndroidRuntime(7974): at android.view.View$PerformClick.run(View.java:17072)
03-24 01:13:44.374: E/AndroidRuntime(7974): at android.os.Handler.handleCallback(Handler.java:615)
03-24 01:13:44.374: E/AndroidRuntime(7974): at android.os.Handler.dispatchMessage(Handler.java:92)
03-24 01:13:44.374: E/AndroidRuntime(7974): at android.os.Looper.loop(Looper.java:153)
03-24 01:13:44.374: E/AndroidRuntime(7974): at android.app.ActivityThread.main(ActivityThread.java:4987)
03-24 01:13:44.374: E/AndroidRuntime(7974): at java.lang.reflect.Method.invokeNative(Native Method)
03-24 01:13:44.374: E/AndroidRuntime(7974): at java.lang.reflect.Method.invoke(Method.java:511)
03-24 01:13:44.374: E/AndroidRuntime(7974): at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:821)
03-24 01:13:44.374: E/AndroidRuntime(7974): at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:584)
03-24 01:13:44.374: E/AndroidRuntime(7974): at dalvik.system.NativeStart.main(Native Method)
谢谢你们。
编辑：
listaddactivity.java的第72行：
myIntent.putExtra(
"custom_object",
new listControlObject(namefield.getText().toString(),
iterator, temperatureFrag.getCurrentTempType(), Integer
.valueOf(powerPercent.getText()
.toString()), Integer
.valueOf(frequencyField.getText()
.toString()),
temperatureFrag.temperaturenumberpicker
.getValue(), cycleFrag.startTimeField
.getCurrentHour(),
cycleFrag.startTimeField.getCurrentMinute(),
cycleFrag.cycleDatePicker.getDayOfMonth(),
cycleFrag.cycleDatePicker.getMonth(), Integer
.valueOf(cycleFrag.numberOfCyclesField
.getText().toString())));
上面只是构造一个新对象，并使用键＆＃34;自定义对象＆＃34;将其添加到intent中。
以下是parcelable对象的代码：
package com.nanospark.upcdemo;
import android.os.Parcel;
import android.os.Parcelable;
public class listControlObject implements Parcelable {
private String name;
private int id;
private int tempType;// 0 for fahrenheit, 1 for celsius.
private int powerPercent;
private int freq;
private int temp;
private int cycleDateDay;
private int cycleDateMonth;
private int numberOfCycles;
private int cycleTimeHour;
private int cycleTimeMinute;
public listControlObject(String name, int id, int tempType,
int powerPercent, int freq, int temp, int cycleTimeHour,
int cycleTimeMinute, int cycleDateDay, int cycleDateMonth,
int numberOfCycles) {
this.id = id;
this.name = name;
this.cycleDateDay = cycleDateDay;
this.cycleDateMonth = cycleDateMonth;
this.cycleTimeHour = cycleTimeHour;
this.cycleTimeMinute = cycleTimeMinute;
this.freq = freq;
this.numberOfCycles = numberOfCycles;
this.powerPercent = powerPercent;
this.temp = temp;
this.tempType = tempType;
}
private listControlObject(Parcel in){
this.id = in.readInt();
this.name = in.readString();
this.cycleDateDay = in.readInt();
this.cycleDateMonth = in.readInt();
this.cycleTimeHour = in.readInt();
this.cycleTimeMinute = in.readInt();
this.freq = in.readInt();
this.numberOfCycles = in.readInt();
this.powerPercent = in.readInt();
this.temp = in.readInt();
this.tempType = in.readInt();
}
public int getCycleDateDay() {
return cycleDateDay;
}
public void setCycleDateDay(int cycleDateDay) {
this.cycleDateDay = cycleDateDay;
}
public int getCycleDateMonth() {
return cycleDateMonth;
}
public void setCycleDateMonth(int cycleDateMonth) {
this.cycleDateMonth = cycleDateMonth;
}
public int getCycleTimeHour() {
return cycleTimeHour;
}
public void setCycleTimeHour(int cycleTimeHour) {
this.cycleTimeHour = cycleTimeHour;
}
public int getCycleTimeMinute() {
return cycleTimeMinute;
}
public void setCycleTimeMinute(int cycleTimeMinute) {
this.cycleTimeMinute = cycleTimeMinute;
}
public int getNumberOfCycles() {
return numberOfCycles;
}
public void setNumberOfCycles(int numberOfCycles) {
this.numberOfCycles = numberOfCycles;
}
public int getTempType() {
return tempType;
}
public void setTempType(int tempType) {
this.tempType = tempType;
}
public String getName() {
return name;
}
public void setName(String name) {
this.name = name;
}
public int getPowerPercent() {
return powerPercent;
}
public void setPowerPercent(int powerPercent) {
this.powerPercent = powerPercent;
}
public int getFreq() {
return freq;
}
public void setFreq(int freq) {
this.freq = freq;
}
public int getTemp() {
return temp;
}
public void setTemp(int temp) {
this.temp = temp;
}
public int getId() {
return id;
}
public void setId(int id) {
this.id = id;
}
@Override
public String toString() {
return this.name;
}
@Override
public int describeContents() {
// TODO Auto-generated method stub
return 0;
}
@Override
public void writeToParcel(Parcel parcel, int flags) {
parcel.writeInt(id);
parcel.writeString(name);
parcel.writeInt(cycleDateDay);
parcel.writeInt(cycleDateMonth);
parcel.writeInt(cycleTimeHour);
parcel.writeInt(cycleTimeMinute);
parcel.writeInt(freq);
parcel.writeInt(numberOfCycles);
parcel.writeInt(powerPercent);
parcel.writeInt(temp);
parcel.writeInt(tempType);
}
public static Creator<listControlObject> CREATOR = new Creator<listControlObject>() {
public listControlObject createFromParcel(Parcel parcel) {
return new listControlObject(parcel);
}
public listControlObject[] newArray(int size) {
return new listControlObject[size];
}
};
}
编辑：
我发现了我的错误来源：
当我需要传递listControlObject时，我正在传递一个包裹。
cyclefragment.a1.add(intent.getParcelableExtra("custom_object"));
cyclefragment.adapter.notifyDataSetChanged();
如何将intent.getParcelableExtra（＆＃34; custom_object＆＃34;）转换回listControlObject？
[UPDATE]
新的Logcat错误：
03-24 02:29:46.177: E/AndroidRuntime(9685): FATAL EXCEPTION: main
03-24 02:29:46.177: E/AndroidRuntime(9685): java.lang.RuntimeException: Unable to start activity ComponentInfo{com.nanospark.upcdemo/com.nanospark.upcdemo.MainActivity}: java.lang.NullPointerException
03-24 02:29:46.177: E/AndroidRuntime(9685): at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2184)
03-24 02:29:46.177: E/AndroidRuntime(9685): at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2211)
03-24 02:29:46.177: E/AndroidRuntime(9685): at android.app.ActivityThread.access$600(ActivityThread.java:149)
03-24 02:29:46.177: E/AndroidRuntime(9685): at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1300)
03-24 02:29:46.177: E/AndroidRuntime(9685): at android.os.Handler.dispatchMessage(Handler.java:99)
03-24 02:29:46.177: E/AndroidRuntime(9685): at android.os.Looper.loop(Looper.java:153)
03-24 02:29:46.177: E/AndroidRuntime(9685): at android.app.ActivityThread.main(ActivityThread.java:4987)
03-24 02:29:46.177: E/AndroidRuntime(9685): at java.lang.reflect.Method.invokeNative(Native Method)
03-24 02:29:46.177: E/AndroidRuntime(9685): at java.lang.reflect.Method.invoke(Method.java:511)
03-24 02:29:46.177: E/AndroidRuntime(9685): at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:821)
03-24 02:29:46.177: E/AndroidRuntime(9685): at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:584)
03-24 02:29:46.177: E/AndroidRuntime(9685): at dalvik.system.NativeStart.main(Native Method)
03-24 02:29:46.177: E/AndroidRuntime(9685): Caused by: java.lang.NullPointerException
03-24 02:29:46.177: E/AndroidRuntime(9685): at com.nanospark.upcdemo.MainActivity.processNewIntent(MainActivity.java:88)
03-24 02:29:46.177: E/AndroidRuntime(9685): at com.nanospark.upcdemo.MainActivity.onCreate(MainActivity.java:70)
03-24 02:29:46.177: E/AndroidRuntime(9685): at android.app.Activity.performCreate(Activity.java:5020)
03-24 02:29:46.177: E/AndroidRuntime(9685): at android.app.Instrumentation.callActivityOnCreate(Instrumentation.java:1080)
03-24 02:29:46.177: E/AndroidRuntime(9685): at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2148)
03-24 02:29:46.177: E/AndroidRuntime(9685): ... 11 more
相关代码：
@Override
protected void onNewIntent(Intent intent) {
super.onNewIntent(intent);
processNewIntent(intent);
}
private void processNewIntent(Intent intent) {
Log.v("TEST", "METHOD CALLED TEST");
if (intent.hasExtra("custom_object")) {
if (intent.getParcelableExtra("custom_object")
.equals(null)) {
Log.v("Testing null", "Object is null");
} else {
Log.v("Testing null", "Object is not null");
cyclefragment.a1.add((listControlObject) intent.getParcelableExtra("custom_object"));
cyclefragment.adapter.notifyDataSetChanged();
}
}
}
logcat错误指的是这一行：
cyclefragment.a1.add((listControlObject) intent.getParcelableExtra("custom_object"));
我做了
private listControlObject(Parcel in){
public listControlObject(Parcel in){
根据评论的要求。仍然收到错误。
答案 0 :(得分：1)
您的跟踪文件似乎已损坏或由另一个进程保留。 Logcat可能会出现错误：Log.d("LISTACTIVITY", "Intent successfully passed!");
或者您检查活动中的所有namefield或temperatureFrag ...，以确保在调用发送活动的onClick（）之前已初始化其实例。
因为您在一个代码行中调用了所有实例，所以很难找出错误。尝试使用DDMS进行调试！
P / S：您的代码中的第72行在哪里？
<强> [UPDATE]
更多细节： Passing a custom Object from one Activity to another Parcelable vs Bundle
如果您已经很好地“包裹”了，那么在您的目标活动中，只需将收到的对象转换为原始类型，就像您在代码中所做的那样。
您的代码错误为private listControlObject(Parcel in) private。更改为public，以便Intent可以使用此构造函数从先前包含的字符串中恢复对象。