问题
The compiler is throwing ClassCastException: String cannot cast be to an int on line 96 of the below. I cannot for the life of me figure out why, and any help would be really appericiated.
code:
public class Progress extends Activity {
private TextView names, current, goal, start;
private EditText updateBox;
private ProgressBar progress;
private String currentWeight, goalS, startS;
private int currentWeightInt, weightUpdate;
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_progress);
SharedPreferences preferences = PreferenceManager.getDefaultSharedPreferences(this);
String name = preferences.getString("name", "You need to create a profile first!");
names = (TextView) findViewById(R.id.noProf);
names.setText("Welcome back " + name);
start = (TextView) findViewById(R.id.start);
startS = preferences.getString("start", "");
start.setText("Start:" + startS);
current = (TextView) findViewById(R.id.currently);
currentWeight = preferences.getString("current", "");
currentWeightInt = Integer.parseInt(currentWeight);
current.setText("currently " + currentWeight);
goal = (TextView) findViewById(R.id.goal);
goalS = preferences.getString("goal", " ");
goal.setText("goal: " + goalS);
progress = (ProgressBar) findViewById(R.id.progressBar1);
}
public void update(View view) {
updateBox = (EditText) findViewById(R.id.updateWeight);
if (updateBox.getText().toString().matches(" ")) {
Toast.makeText(this, "Please enter a weight", Toast.LENGTH_LONG).show();
}
else {
weightUpdate = Integer.parseInt(updateBox.getText().toString());
if (weightUpdate > currentWeightInt) {
weightGain();
Toast.makeText(this, "weight gain", Toast.LENGTH_LONG).show();
}
else if (weightUpdate < currentWeightInt) {
Toast.makeText(this, "weight loss", Toast.LENGTH_LONG).show();
weightLoss();
}
else {
Toast.makeText(this, "stayed the same", Toast.LENGTH_LONG).show();
}
}
}
@Override
public boolean onCreateOptionsMenu(Menu menu) {
// Inflate the menu; this adds items to the action bar if it is present.
getMenuInflater().inflate(R.menu.progress, menu);
return true;
}
private void weightGain() {
if (weightUpdate > currentWeightInt) {
SharedPreferences preferences = PreferenceManager.getDefaultSharedPreferences(this);
SharedPreferences.Editor editor = preferences.edit();
editor.putString("current", Integer.toString(weightUpdate));
editor.commit();
}
}
private void weightLoss() {
if (weightUpdate < currentWeightInt) {
SharedPreferences preferences = PreferenceManager.getDefaultSharedPreferences(this);
int toSet = preferences.getInt("progress",0);
progress.setProgress(toSet);
SharedPreferences.Editor editor = preferences.edit();
editor.putString("current", Integer.toString(weightUpdate));
editor.commit();
double first = (Double.parseDouble(startS) - Double
.parseDouble(currentWeight));
double second = (Double.parseDouble(startS) - Double
.parseDouble(goalS));
double last = first / second;
double result = last * 100;
int resultInt = (int) result;
progress.setProgress(resultInt);
editor.putInt("progress", resultInt);
editor.commit();
Intent refresh = new Intent(this, Progress.class);
startActivity(refresh);
this.finish();
}
}
}
Stack trace:
08-17 18:44:25.565: D/qdmemalloc(11781): ion: Mapped buffer base:0x6c501000 size:8355840 offset:0 fd:56
08-17 18:44:25.565: D/qdmemalloc(11781): ion: Mapped buffer base:0x67680000 size:4096 offset:0 fd:57
08-17 18:44:28.418: D/qdmemalloc(11781): ion: Mapped buffer base:0x6cd09000 size:8355840 offset:0 fd:58
08-17 18:44:28.418: D/qdmemalloc(11781): ion: Mapped buffer base:0x67b33000 size:4096 offset:0 fd:59
08-17 18:44:29.459: I/InputMethodManager(11781): windowGainedFocus, mServedView=android.widget.EditText{4188f960 VFED..CL .F....ID 225,921-855,1039 #7f08001b app:id/updateWeight}, inputType=0x2, softInputMode=0x120, pid=11781
08-17 18:44:29.509: D/qdmemalloc(11781): ion: Mapped buffer base:0x6d668000 size:8355840 offset:0 fd:61
08-17 18:44:29.509: D/qdmemalloc(11781): ion: Mapped buffer base:0x67cca000 size:4096 offset:0 fd:62
08-17 18:44:29.529: D/qdmemalloc(11781): ion: Unmapping buffer base:0x6bbe9000 size:8355840
08-17 18:44:29.529: D/qdmemalloc(11781): ion: Unmapping buffer base:0x6720d000 size:4096
08-17 18:44:29.529: D/qdmemalloc(11781): ion: Unmapping buffer base:0x6c501000 size:8355840
08-17 18:44:29.529: D/qdmemalloc(11781): ion: Unmapping buffer base:0x67680000 size:4096
08-17 18:44:29.529: D/qdmemalloc(11781): ion: Unmapping buffer base:0x6cd09000 size:8355840
08-17 18:44:29.529: D/qdmemalloc(11781): ion: Unmapping buffer base:0x67b33000 size:4096
08-17 18:44:29.980: D/qdmemalloc(11781): ion: Mapped buffer base:0x6bbe9000 size:8355840 offset:0 fd:54
08-17 18:44:29.980: D/qdmemalloc(11781): ion: Mapped buffer base:0x6720d000 size:4096 offset:0 fd:56
08-17 18:44:30.270: D/qdmemalloc(11781): ion: Mapped buffer base:0x6c501000 size:8355840 offset:0 fd:57
08-17 18:44:30.270: D/qdmemalloc(11781): ion: Mapped buffer base:0x67680000 size:4096 offset:0 fd:58
08-17 18:44:35.976: W/dalvikvm(11781): threadid=1: thread exiting with uncaught exception (group=0x413feba0)
08-17 18:44:36.006: E/AndroidRuntime(11781): FATAL EXCEPTION: main
08-17 18:44:36.006: E/AndroidRuntime(11781): java.lang.IllegalStateException: Could not execute method of the activity
08-17 18:44:36.006: E/AndroidRuntime(11781): at android.view.View$1.onClick(View.java:3626)
08-17 18:44:36.006: E/AndroidRuntime(11781): at android.view.View.performClick(View.java:4231)
08-17 18:44:36.006: E/AndroidRuntime(11781): at android.view.View$PerformClick.run(View.java:17537)
08-17 18:44:36.006: E/AndroidRuntime(11781): at android.os.Handler.handleCallback(Handler.java:725)
08-17 18:44:36.006: E/AndroidRuntime(11781): at android.os.Handler.dispatchMessage(Handler.java:92)
08-17 18:44:36.006: E/AndroidRuntime(11781): at android.os.Looper.loop(Looper.java:158)
08-17 18:44:36.006: E/AndroidRuntime(11781): at android.app.ActivityThread.main(ActivityThread.java:5777)
08-17 18:44:36.006: E/AndroidRuntime(11781): at java.lang.reflect.Method.invokeNative(Native Method)
08-17 18:44:36.006: E/AndroidRuntime(11781): at java.lang.reflect.Method.invoke(Method.java:511)
08-17 18:44:36.006: E/AndroidRuntime(11781): at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:1083)
08-17 18:44:36.006: E/AndroidRuntime(11781): at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:850)
08-17 18:44:36.006: E/AndroidRuntime(11781): at dalvik.system.NativeStart.main(Native Method)
08-17 18:44:36.006: E/AndroidRuntime(11781): Caused by: java.lang.reflect.InvocationTargetException
08-17 18:44:36.006: E/AndroidRuntime(11781): at java.lang.reflect.Method.invokeNative(Native Method)
08-17 18:44:36.006: E/AndroidRuntime(11781): at java.lang.reflect.Method.invoke(Method.java:511)
08-17 18:44:36.006: E/AndroidRuntime(11781): at android.view.View$1.onClick(View.java:3621)
08-17 18:44:36.006: E/AndroidRuntime(11781): ... 11 more
08-17 18:44:36.006: E/AndroidRuntime(11781): Caused by: java.lang.ClassCastException: java.lang.String cannot be cast to java.lang.Integer
08-17 18:44:36.006: E/AndroidRuntime(11781): at android.app.SharedPreferencesImpl.getInt(SharedPreferencesImpl.java:240)
08-17 18:44:36.006: E/AndroidRuntime(11781): at com.example.smallchangebigloss.Progress.weightLoss(Progress.java:96)
08-17 18:44:36.006: E/AndroidRuntime(11781): at com.example.smallchangebigloss.Progress.update(Progress.java:63)
08-17 18:44:36.006: E/AndroidRuntime(11781): ... 14 more
回答1:
Fixed this one- as rightly pointed out by you all the code was correct. The issue was that I had previously changed the value of progress in preferences from a string to an int. This meant when retrieving it the first time it was still a string. To rectify this was as simple as uninstalling the application form my phone and reinstalling it. Got some new issues now but not with this section of code. Thanks for your help everyone.
回答2:
I suppose that in the line of where you actually save the "progress" into the SharedPreferences, you will accidentially be saving a String instead of an Integer.
Then, upon trying to get the saved value you run into a ClassCastException because the saved value is actually a String and not an Integer.
UPDATE:
Try getting the SharedPreferences like this:
SharedPreferences sp = c.getSharedPreferences("MySharedPrefs", 0);
Also consider cleaning your project.
I also cant understand why you restart your Activity everytime you call weightLoss(), could you explain?
Intent refresh = new Intent(this, Progress.class);
startActivity(refresh);
this.finish();
This is how you should refresh your UI-Components:
Simply create a refresh method that reads the values out of the SharedPreferences anytime you want and sets them to the TextViews.
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_progress);
names = (TextView) findViewById(R.id.noProf);
start = (TextView) findViewById(R.id.start);
current = (TextView) findViewById(R.id.currently);
goal = (TextView) findViewById(R.id.goal);
progress = (ProgressBar) findViewById(R.id.progressBar1);
refresh(); // call this method everytime you want to update the textviews and so on...
}
// CALL THIS METHOD EVERYTIME YOU WANT TO REFRESH INSTEAD OF RESTARTING YOUR ACTIVITY
public void refresh() {
SharedPreferences preferences = PreferenceManager.getDefaultSharedPreferences(this);
String name = preferences.getString("name", "You need to create a profile first!");
names.setText("Welcome back " + name);
startS = preferences.getString("start", "");
start.setText("Start:" + startS);
currentWeight = preferences.getString("current", "");
currentWeightInt = Integer.parseInt(currentWeight);
current.setText("currently " + currentWeight);
goalS = preferences.getString("goal", " ");
goal.setText("goal: " + goalS);
}
// your other methods...
private void weightLoss() {
if (weightUpdate < currentWeightInt) {
SharedPreferences preferences = PreferenceManager.getDefaultSharedPreferences(this);
int toSet = preferences.getInt("progress",0);
progress.setProgress(toSet);
SharedPreferences.Editor editor = preferences.edit();
editor.putString("current", Integer.toString(weightUpdate));
editor.commit();
double first = (Double.parseDouble(startS) - Double
.parseDouble(currentWeight));
double second = (Double.parseDouble(startS) - Double
.parseDouble(goalS));
double last = first / second;
double result = last * 100;
int resultInt = (int) result;
progress.setProgress(resultInt);
editor.putInt("progress", resultInt);
editor.commit();
refresh(); // DO THIS HERE INSTEAD OF RESTARTING THE ACTIVITY
}
}
来源：https://stackoverflow.com/questions/18291551/classcastexception-using-sharedpreferences