Question

我一直试图寻找答案，但我唯一理解的是我的代码第22行出了点问题，但我不明白为什么。我确定它有点蠢，但我昨天开始编写android代码，请原谅我！

我的代码是：

import android.content.Intent;
import android.support.v7.app.AppCompatActivity;
import android.os.Bundle;
import android.view.View;
import android.widget.CheckBox;
import android.widget.Toast;

public class Benvenuto extends AppCompatActivity {

@Override
protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.activity_benvenuto);
       }



public void entra(View view) {
    Intent entra1 = new Intent(this, domande1.class);
    boolean checked = ((CheckBox) view).isChecked();

    switch (view.getId()) {
        case R.id.condizioni:
            if (checked)
                startActivity(entra1);
            else
                Toast.makeText(this, "Devi approvare termini e condizioni prima di procedere!", Toast.LENGTH_SHORT).show();
            break;
    }

}
}

因此，基本上，用户必须同意条款和条件。如果他同意，那么他会跳到下一个活动。如果没有，就会出现祝酒词！

但是当按下按钮时应用程序崩溃（在添加复选框之前，它工作正常）。

我得到的错误是

E/AndroidRuntime: FATAL EXCEPTION: main
              Process: com.suspicio.turboscuse, PID: 547
              java.lang.IllegalStateException: Could not execute method for android:onClick
                  at android.support.v7.app.AppCompatViewInflater$DeclaredOnClickListener.onClick(AppCompatViewInflater.java:293)
                  at android.view.View.performClick(View.java:5201)
                  at android.view.View$PerformClick.run(View.java:21209)
                  at android.os.Handler.handleCallback(Handler.java:739)
                  at android.os.Handler.dispatchMessage(Handler.java:95)
                  at android.os.Looper.loop(Looper.java:148)
                  at android.app.ActivityThread.main(ActivityThread.java:5525)
                  at java.lang.reflect.Method.invoke(Native Method)
                  at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:730)
                  at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:620)
               Caused by: java.lang.reflect.InvocationTargetException
                  at java.lang.reflect.Method.invoke(Native Method)
                  at android.support.v7.app.AppCompatViewInflater$DeclaredOnClickListener.onClick(AppCompatViewInflater.java:288)
                  at android.view.View.performClick(View.java:5201) 
                  at android.view.View$PerformClick.run(View.java:21209) 
                  at android.os.Handler.handleCallback(Handler.java:739) 
                  at android.os.Handler.dispatchMessage(Handler.java:95) 
                  at android.os.Looper.loop(Looper.java:148) 
                  at android.app.ActivityThread.main(ActivityThread.java:5525) 
                  at java.lang.reflect.Method.invoke(Native Method) 
                  at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:730) 
                  at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:620) 
               Caused by: java.lang.ClassCastException: android.support.v7.widget.AppCompatButton cannot be cast to android.widget.CheckBox
                  at com.suspicio.turboscuse.Benvenuto.entra(Benvenuto.java:22)
                  at java.lang.reflect.Method.invoke(Native Method) 
                  at android.support.v7.app.AppCompatViewInflater$DeclaredOnClickListener.onClick(AppCompatViewInflater.java:288) 
                  at android.view.View.performClick(View.java:5201) 
                  at android.view.View$PerformClick.run(View.java:21209) 
                  at android.os.Handler.handleCallback(Handler.java:739) 
                  at android.os.Handler.dispatchMessage(Handler.java:95) 
                  at android.os.Looper.loop(Looper.java:148) 
                  at android.app.ActivityThread.main(ActivityThread.java:5525) 
                  at java.lang.reflect.Method.invoke(Native Method) 
                  at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:730) 
                  at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:620)

你能帮我吗？

Answer 1

问题是view变量不是CheckBox，它似乎是AppCompatButton。

您可以将支票更改为以下内容：

if(view instanceof CheckBox){
   // The checkbox was pressed
   if(((CheckBox) view).isChecked()){
      // The checkbox is checked
      startActivity(entra1);
   }else{
     // The checkbox is not checked
     Toast.makeText(this, "Devi approvare termini e condizioni prima di procedere!", Toast.LENGTH_SHORT).show();
   }
}else{
    // The button was pressed
}

Answer 2

试试这个：

import java.util.Scanner;
public class DataAnalyze {
public static void main(String[] args) {
Scanner input = new Scanner(System.in);

int i, j, k, sampleSum = 0; /* the variables that will be used */
int minimum = Integer.MAX_VALUE, maximum = Integer.MIN_VALUE; /* This     will be used to find min and max */
int[] trialAvg = new int [5];

System.out.println("Please enter the sample size: "); 
int sampleSize = input.nextInt();
long [][] arr = new long[5][sampleSize+1]; /* using long as it will be a larger size */

for(i = 0, k = 0; i < 4; sampleSum = 0, i++, k = 0) {
    System.out.println(" Enter numbers for Trial: " + (i + 1));
    /* asking user to input numbers for trials with for loop */
    for (j = 0; j < sampleSize; j++, k++) {
        System.out.println("Enter Sample # " + (k +1) + ":");
        arr[i][j]= input.nextInt();
        sampleSum += arr[i][j];
        /* the sampSum will equal arr[i][j] */
    }
     trialAvg[i] = sampleSum/sampleSize;
     System.out.println("");
     /* finding average */
}
for (i = 0; i < 4; i++) {
    if(maximum < trialAvg[i])
        maximum = trialAvg[i];

    /* testing to find min and max */

    if(minimum > trialAvg[i])
        minimum = trialAvg[i];
}
System.out.println("\tSample # \tTrial 1 \t\tTrial 2 \t\tTrial 3 \t\tTrial 4");
/* using \t to set it in table format and save it */

for ( i = 0; sampleSize < 4; i++) {
    System.out.println("\t " + (i + 1) + "\t\t "  + arr[0][i] + "\t\t " + arr[1][i] + "\t\t " + arr[2][i] + "\t\t " + arr[3][i]);
}

System.out.println("-----------------------------------------------------------------------------------");
System.out.println("Average:\t\t " + trialAvg[0] + "\t\t " + trialAvg[1] + "\t\t " + trialAvg[2] + "\t\t " + trialAvg[3]);

System.out.println("Minimum Average: " + minimum);
System.out.println("Maximum Average: " + maximum);
System.out.println("");

if(maximum < (minimum*2))
    System.out.println("The trials concur with each other!");
else if (maximum == minimum)
    System.out.println("The trials match EXACTLY!");
else
    System.out.println("The trials do NOT concur!");

input.close();

}

}

在xml中：

public void itemClicked(View v) {
  CheckBox checkBox = (CheckBox) v;
  if(checkBox.isChecked())
     startActivity(entra1);
  else
     Toast.makeText(this, "Devi approvare termini e condizioni prima di procedere!", Toast.LENGTH_SHORT).show();
}

致命异常（java.lang.IllegalStateException）

2 个答案: