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Why this code Force Quits?

开发者 https://www.devze.com 2023-02-10 00:59 出处:网络
I have starting learning Java and android application development side-by-side. Currently, I a String-array colorsArray which I am trying to print using Log.v

I have starting learning Java and android application development side-by-side. Currently, I a String-array colorsArray which I am trying to print using Log.v

    <?xml version="1.0" encoding="utf-8"?>
<resources>
    <string name="hello">Hello World, defaultActivity!</string>
    <string name="app_name">Challenge</string>
    <string name="red">Red</string>  
    <string name="orange">Orange</string>  
    <string name="yellow">Yellow</string>  
    <string name="green">Green</string>  
    <string name="blue">Blue</string>  
    <string name="indigo">Indigo</string>  
    <string name="violet">Violet</string>  
    <string-array name="colorsArray">  
        <item>@string/red</item>  
        <item>@string/orange</item>  
        <item>@string/yellow</item>  
        <item>@string/green</item>  
        <item>@string/blue</item>  
        <item>@string/indigo</item>  
        <item>@string/violet</item>  
    </string-array>  
</resources>

Now I am trying to print that array in different ways, just for practice.

package com.gaurish.challenge;

import android.app.Activity;
import android.os.Bundle;
import android.util.Log;

public class defaultActivity extends Acti开发者_Python百科vity {
    /** Called when the activity is first created. */
    public static final String DEBUG_TAG = "PracticeApp";


@Override
public void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.main);
    String aColors[] = getResources().getStringArray(R.array.colorsArray);
    printUsingForEach(aColors);
    printUsingWhile(aColors);
    printReverse(aColors);
}

private void printUsingForEach(String[] aColors) {
    for(String i : aColors) {
        Log.v(DEBUG_TAG, "String array printed using for each loop: " + i);
    }
}

private void printUsingWhile(String[] aColors) {
    byte i=0;
    while(i<=aColors.length) {
        Log.v(DEBUG_TAG, "String array printed using While loop: " + aColors[i++]);
    }
}

private void printReverse(String[] aColors) {
    int i=aColors.length -1;
    while(i> (-1) ) {
        Log.v(DEBUG_TAG, "String array printed in reverse order -> " + aColors[i--]);
    }
}
}

printUsingForEach() & printUsingWhile() run just fine but printReverse method just not run, the application force quits before reaching. here is the log I am building against android 1.6

Please guide this n00b, why this is happening


You have a bug in your code:

while(i<=aColors.length) { ... }

This will cause a loop iteration with i = aColors.length, which is out of bounds.

You can see this in your log:

02-13 15:24:24.226: ERROR/AndroidRuntime(396): java.lang.RuntimeException: Unable to start activity ComponentInfo{com.gaurish.challenge/com.gaurish.challenge.defaultActivity}: java.lang.ArrayIndexOutOfBoundsException
02-13 15:24:24.226: ERROR/AndroidRuntime(396): Caused by: java.lang.ArrayIndexOutOfBoundsException
02-13 15:24:24.226: ERROR/AndroidRuntime(396):     at com.gaurish.challenge.defaultActivity.printUsingWhile(defaultActivity.java:31)
0

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