编译器抛出ClassCastException：String无法转换为下面第96行的int。我不能为我的生活找出原因，任何帮助都会得到真正的体谅。
代码：
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();
}
}
}
堆栈追踪：
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
答案 0 :(得分：0)
我认为在实际将“进度”保存到SharedPreferences的行中，您将意外地保存字符串而不是整数。
然后，在尝试获取保存的值时，您会遇到ClassCastException，因为保存的值实际上是String而不是Integer。
<强>更新
尝试像这样获取SharedPreferences：
SharedPreferences sp = c.getSharedPreferences("MySharedPrefs", 0);
还要考虑清理项目。
每次调用weightLoss（）时，我也无法理解你重启活动的原因，你能解释一下吗？
Intent refresh = new Intent(this, Progress.class);
startActivity(refresh);
this.finish();
这是刷新UI组件的方法：
只需创建一个刷新方法，随时读取SharedPreferences中的值，并将它们设置为TextView。
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
}
}
答案 1 :(得分：0)
修正了这一点 - 正如你所正确指出的那样，所有代码都是正确的。问题是我之前已将首选项的进度值从字符串更改为int。这意味着在第一次检索它时仍然是一个字符串。要纠正这个问题就像从手机上卸载应用程序并重新安装一样简单。现在遇到了一些新问题，但这部分代码没有。感谢大家的帮助。