我写了一个android程序。当我点击第一个活动时，第二个活动无法显示。如何使用关键字＆＃39; final`声明imageview以及如何编写私有方法。拜托，任何人都可以帮我解决我的错误。感谢您的帮助。
SecondActivity.java
public class SecondActivity extends Activity {
Button btnPrevious= null;
Button btnNext = null;
TextView txtTest = null;
int conditions[];
String days[];
// condition imageView initialization together with declaration
final ImageView T1C4R4 = (ImageView) findViewById(R.id.T1C4R4);
final ImageView T2C4R5 = (ImageView) findViewById(R.id.T2C4R5);
final ImageView T4C4R1 = (ImageView) findViewById(R.id.T4C4R1);
final ImageView T3C4R1 = (ImageView) findViewById(R.id.T3C4R1);
// imageView initialization together with declaration
final ImageView T1C4R1 = (ImageView) findViewById(R.id.T1C4R1);
final ImageView T1C2R3 = (ImageView) findViewById(R.id.T1C2R3);
final ImageView T1C1R4 = (ImageView) findViewById(R.id.T1C1R4);
final ImageView T2C4R1 = (ImageView) findViewById(R.id.T2C4R1);
final ImageView T2C2R3 = (ImageView) findViewById(R.id.T2C2R3);
final ImageView T2C1R5 = (ImageView) findViewById(R.id.T2C1R5);
final ImageView T4C1R1 = (ImageView) findViewById(R.id.T4C1R1);
final ImageView T4C2R2 = (ImageView) findViewById(R.id.T4C2R2);
final ImageView T4C5R5 = (ImageView) findViewById(R.id.T4C5R5);
final ImageView T3C4R5 = (ImageView) findViewById(R.id.T3C4R5);
final ImageView T3C2R3 = (ImageView) findViewById(R.id.T3C2R3);
final ImageView T3C1R1 = (ImageView) findViewById(R.id.T3C1R1);
final ImageView[][] dressImageView =
{
{T1C4R1, T1C2R3, T1C1R4},
{T2C4R1,T2C2R3, T2C1R5} ,
{T4C1R1, T4C2R2,T4C5R5},
{T3C4R5, T3C2R3, T3C1R1}
};
final ImageView [] dayCell = {T1C4R4 ,T2C4R5, T4C4R1, T3C4R1 };
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.second_activity);
//ImageView Initialization
btnPrevious = (Button) findViewById(R.id.btnPrevious2);
btnNext = (Button) findViewById(R.id.btnNext2);
txtTest = (TextView) findViewById(R.id.txtTest2);
// get the Intent that started this Activity
Intent in = getIntent();
// get the Bundle that stores the data of this Activity
Bundle b = in.getExtras();
// getting data from bundle
conditions = b.getIntArray("condition");
days = b.getStringArray("day");
// show data to layout
txtTest.setText("[Condition: " + conditions[0] + ", " + conditions[1] + ", " + conditions[2] + ", " + conditions[3] + "]");
for (int dc = 0; dc < conditions.length; dc++) {
dayWeatherCondtion(dc, days[dc]); // 0 --- Today
weatherConditionDress(dc, conditions[dc]); // 0 10
}
btnPrevious.setOnClickListener(new OnClickListener() {
@Override
public void onClick(View v) {
// TODO Auto-generated method stub
}
});
btnNext.setOnClickListener(new OnClickListener() {
@Override
public void onClick(View v) {
Bundle b = new Bundle();
b.putInt("condition", conditions[1]);
b.putString("day", days[1]);
// Creating Intent object
Intent in = new Intent(SecondActivity.this, DetailActivity.class);
// Storing bundle object into intent
in.putExtras(b);
startActivity(in);
}
});
}
private void weatherConditionDress(int day, int condition) { // 0 ---- 10
switch(condition){
case 2:
{
//String dress_array[] = ;
weatherDress(day, getResources().getStringArray(R.array.five)); //0 -----
break;
}
case 5:
case 6:
{
// String dress_array[] = getResources().getStringArray(R.array.five);
weatherDress(day, getResources().getStringArray(R.array.five));
break;
}
case 9:
{
// String dress_array[] = getResources().getStringArray(R.array.five);
weatherDress(day, getResources().getStringArray(R.array.nine));
break;
}
case 11:
{
//weatherCondtion(day, getResources().getStringArray(R.string.condition_11));
//String dress_array[] = getResources().getStringArray(R.array.five);
//weatherDress(getResources().getStringArray(R.array.five));
break;
}
case 12:
{
//String dress_array[] = getResources().getStringArray(R.array.five);
weatherDress(day, getResources().getStringArray(R.array.five));
break;
}
case 25:
{
// String dress_array[] = getResources().getStringArray(R.array.five);
weatherDress(day, getResources().getStringArray(R.array.twentyFive));
break;
}
case 26:
case 27:
case 28:
case 29:
case 30:
case 31:
{
// String dress_array[] = getResources().getStringArray(R.array.five);
weatherDress(day, getResources().getStringArray(R.array.twentySix));
break;
}
case 36:
{
// String dress_array[] = getResources().getStringArray(R.array.five);
weatherDress(day, getResources().getStringArray(R.array.thirtySix));
break;
}
case 37:
case 38:
case 39:
case 44:
{
// String dress_array[] = getResources().getStringArray(R.array.five);
weatherDress(day, getResources().getStringArray(R.array.thirtySeven));
break;
}
}
}
private void dayWeatherCondtion(int index, String day) {
dayCell[index].setImageDrawable(getDrawableByName(this,day));
Log.d("DAY","Day is " + day);
}
private void weatherDress(int day, String[] dress_array) {
for(int d = 0; d < dress_array.length; d++ ){
//ImageView temp = dressImageView[d];
Log.d("Dress Image", " "+ dressImageView[day][d]);
dressImageView[day][d].setImageDrawable(getDrawableByName(this, dress_array[d]));
}
}
public Drawable getDrawableByName(Context context, String name){
Resources resources = context.getResources();
final int resourceId = resources.getIdentifier(name, "drawable",
context.getPackageName());
return resources.getDrawable(resourceId);
}
}
错误：
11-16 20:58:37.532: D/AndroidRuntime(1331): Shutting down VM
11-16 20:58:37.532: W/dalvikvm(1331): threadid=1: thread exiting with uncaught exception (group=0xa6297288)
11-16 20:58:37.532: E/AndroidRuntime(1331): FATAL EXCEPTION: main
11-16 20:58:37.532: E/AndroidRuntime(1331): java.lang.RuntimeException: Unable to instantiate activity ComponentInfo{com.easy2access.weatherapp/com.easy2access.weatherapp.SecondActivity}: java.lang.NullPointerException
11-16 20:58:37.532: E/AndroidRuntime(1331): at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:1983)
11-16 20:58:37.532: E/AndroidRuntime(1331): at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2084)
11-16 20:58:37.532: E/AndroidRuntime(1331): at android.app.ActivityThread.access$600(ActivityThread.java:130)
11-16 20:58:37.532: E/AndroidRuntime(1331): at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1195)
11-16 20:58:37.532: E/AndroidRuntime(1331): at android.os.Handler.dispatchMessage(Handler.java:99)
11-16 20:58:37.532: E/AndroidRuntime(1331): at android.os.Looper.loop(Looper.java:137)
11-16 20:58:37.532: E/AndroidRuntime(1331): at android.app.ActivityThread.main(ActivityThread.java:4745)
11-16 20:58:37.532: E/AndroidRuntime(1331): at java.lang.reflect.Method.invokeNative(Native Method)
11-16 20:58:37.532: E/AndroidRuntime(1331): at java.lang.reflect.Method.invoke(Method.java:511)
11-16 20:58:37.532: E/AndroidRuntime(1331): at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:786)
11-16 20:58:37.532: E/AndroidRuntime(1331): at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:553)
11-16 20:58:37.532: E/AndroidRuntime(1331): at dalvik.system.NativeStart.main(Native Method)
11-16 20:58:37.532: E/AndroidRuntime(1331): Caused by: java.lang.NullPointerException
11-16 20:58:37.532: E/AndroidRuntime(1331): at android.app.Activity.findViewById(Activity.java:1825)
11-16 20:58:37.532: E/AndroidRuntime(1331): at com.easy2access.weatherapp.SecondActivity.<init>(SecondActivity.java:27)
11-16 20:58:37.532: E/AndroidRuntime(1331): at java.lang.Class.newInstanceImpl(Native Method)
11-16 20:58:37.532: E/AndroidRuntime(1331): at java.lang.Class.newInstance(Class.java:1319)
11-16 20:58:37.532: E/AndroidRuntime(1331): at android.app.Instrumentation.newActivity(Instrumentation.java:1053)
11-16 20:58:37.532: E/AndroidRuntime(1331): at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:1974)
11-16 20:58:37.532: E/AndroidRuntime(1331): ... 11 more
答案 0 :(得分：1)
始终在onCreate（）中找到您的观点。
SecondActivity.java
public class SecondActivity extends Activity {
// Here your Global Declaration.
final ImageView[][] dressImageView;
final ImageView[] dayCell;
Button btnPrevious = null;
Button btnNext = null;
TextView txtTest = null;
int conditions[];
String days[];
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.second_activity);
// ImageView Initialization
// change made here.This all ImageView find inside onCreate().
// condition imageView initialization together with declaration
final ImageView T1C4R4 = (ImageView) findViewById(R.id.T1C4R4);
final ImageView T2C4R5 = (ImageView) findViewById(R.id.T2C4R5);
final ImageView T4C4R1 = (ImageView) findViewById(R.id.T4C4R1);
final ImageView T3C4R1 = (ImageView) findViewById(R.id.T3C4R1);
// imageView initialization together with declaration
final ImageView T1C4R1 = (ImageView) findViewById(R.id.T1C4R1);
final ImageView T1C2R3 = (ImageView) findViewById(R.id.T1C2R3);
final ImageView T1C1R4 = (ImageView) findViewById(R.id.T1C1R4);
final ImageView T2C4R1 = (ImageView) findViewById(R.id.T2C4R1);
final ImageView T2C2R3 = (ImageView) findViewById(R.id.T2C2R3);
final ImageView T2C1R5 = (ImageView) findViewById(R.id.T2C1R5);
final ImageView T4C1R1 = (ImageView) findViewById(R.id.T4C1R1);
final ImageView T4C2R2 = (ImageView) findViewById(R.id.T4C2R2);
final ImageView T4C5R5 = (ImageView) findViewById(R.id.T4C5R5);
final ImageView T3C4R5 = (ImageView) findViewById(R.id.T3C4R5);
final ImageView T3C2R3 = (ImageView) findViewById(R.id.T3C2R3);
final ImageView T3C1R1 = (ImageView) findViewById(R.id.T3C1R1);
dressImageView={{T1C4R1,T1C2R3,T1C1R4},{T2C4R1,T2C2R3,T2C1R5},{T4C1R1,T4C2R2,T4C5R5},{T3C4R5,T3C2R3,T3C1R1}};
dayCell={T1C4R4,T2C4R5,T4C4R1,T3C4R1};
btnPrevious = (Button) findViewById(R.id.btnPrevious2);
btnNext = (Button) findViewById(R.id.btnNext2);
txtTest = (TextView) findViewById(R.id.txtTest2);
// get the Intent that started this Activity
Intent in = getIntent();
// get the Bundle that stores the data of this Activity
Bundle b = in.getExtras();
// getting data from bundle
conditions = b.getIntArray("condition");
days = b.getStringArray("day");
// show data to layout
txtTest.setText("[Condition: " + conditions[0] + ", " + conditions[1] + ", " + conditions[2] + ", "
+ conditions[3] + "]");
/*
* for (int dc = 0; dc < conditions.length; dc++) {
* dayWeatherCondtion(dc, days[dc]); // 0 --- Today
* weatherConditionDress(dc, conditions[dc]); // 0 10 }
*/
btnPrevious.setOnClickListener(new OnClickListener() {
@Override
public void onClick(View v) {
// TODO Auto-generated method stub
}
});
btnNext.setOnClickListener(new OnClickListener() {
@Override
public void onClick(View v) {
Bundle b = new Bundle();
b.putInt("condition", conditions[1]);
b.putString("day", days[1]);
// Creating Intent object
Intent in = new Intent(SecondActivity.this, DetailActivity.class);
// Storing bundle object into intent
in.putExtras(b);
startActivity(in);
}
});
}
/*private void weatherConditionDress(int day, int condition) { // 0 ---- 10
switch(condition){
case 2:
{
//String dress_array[] = ;
weatherDress(day, getResources().getStringArray(R.array.five)); //0 -----
break;
}
case 5:
case 6:
{
// String dress_array[] = getResources().getStringArray(R.array.five);
weatherDress(day, getResources().getStringArray(R.array.five));
break;
}
case 9:
{
// String dress_array[] = getResources().getStringArray(R.array.five);
weatherDress(day, getResources().getStringArray(R.array.nine));
break;
}
case 11:
{
//weatherCondtion(day, getResources().getStringArray(R.string.condition_11));
//String dress_array[] = getResources().getStringArray(R.array.five);
//weatherDress(getResources().getStringArray(R.array.five));
break;
}
case 12:
{
//String dress_array[] = getResources().getStringArray(R.array.five);
weatherDress(day, getResources().getStringArray(R.array.five));
break;
}
case 25:
{
// String dress_array[] = getResources().getStringArray(R.array.five);
weatherDress(day, getResources().getStringArray(R.array.twentyFive));
break;
}
case 26:
case 27:
case 28:
case 29:
case 30:
case 31:
{
// String dress_array[] = getResources().getStringArray(R.array.five);
weatherDress(day, getResources().getStringArray(R.array.twentySix));
break;
}
case 36:
{
// String dress_array[] = getResources().getStringArray(R.array.five);
weatherDress(day, getResources().getStringArray(R.array.thirtySix));
break;
}
case 37:
case 38:
case 39:
case 44:
{
// String dress_array[] = getResources().getStringArray(R.array.five);
weatherDress(day, getResources().getStringArray(R.array.thirtySeven));
break;
}
}
}
private void dayWeatherCondtion(int index, String day) {
dayCell[index].setImageDrawable(getDrawableByName(this,day));
Log.d("DAY","Day is " + day);
}
private void weatherDress(int day, String[] dress_array) {
for(int d = 0; d < dress_array.length; d++ ){
//ImageView temp = dressImageView[d];
Log.d("Dress Image", " "+ dressImageView[day][d]);
dressImageView[day][d].setImageDrawable(getDrawableByName(this, dress_array[d]));
}
}
//
public Drawable getDrawableByName(Context context, String name){
Resources resources = context.getResources();
final int resourceId = resources.getIdentifier(name, "drawable",
context.getPackageName());
return resources.getDrawable(resourceId);
}
}
答案 1 :(得分：1)
在setcontentview
之后移动视图的初始化 public class SecondActivity extends Activity {
Button btnPrevious= null;
Button btnNext = null;
TextView txtTest = null;
int conditions[];
String days[];
/*final ImageView[][] dressImageView =
{
{T1C4R1, T1C2R3, T1C1R4},
{T2C4R1,T2C2R3, T2C1R5} ,
{T4C1R1, T4C2R2,T4C5R5},
{T3C4R5, T3C2R3, T3C1R1}
};
final ImageView [] dayCell = {T1C4R4 ,T2C4R5, T4C4R1, T3C4R1 };*/
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.second_activity);
//ImageView Initialization
// move initialisation here
// condition imageView initialisation together with declaration
final ImageView T1C4R4 = (ImageView) findViewById(R.id.T1C4R4);
final ImageView T2C4R5 = (ImageView) findViewById(R.id.T2C4R5);
final ImageView T4C4R1 = (ImageView) findViewById(R.id.T4C4R1);
final ImageView T3C4R1 = (ImageView) findViewById(R.id.T3C4R1);
// imageView initialization together with declaration
final ImageView T1C4R1 = (ImageView) findViewById(R.id.T1C4R1);
final ImageView T1C2R3 = (ImageView) findViewById(R.id.T1C2R3);
final ImageView T1C1R4 = (ImageView) findViewById(R.id.T1C1R4);
final ImageView T2C4R1 = (ImageView) findViewById(R.id.T2C4R1);
final ImageView T2C2R3 = (ImageView) findViewById(R.id.T2C2R3);
final ImageView T2C1R5 = (ImageView) findViewById(R.id.T2C1R5);
final ImageView T4C1R1 = (ImageView) findViewById(R.id.T4C1R1);
final ImageView T4C2R2 = (ImageView) findViewById(R.id.T4C2R2);
final ImageView T4C5R5 = (ImageView) findViewById(R.id.T4C5R5);
final ImageView T3C4R5 = (ImageView) findViewById(R.id.T3C4R5);
final ImageView T3C2R3 = (ImageView) findViewById(R.id.T3C2R3);
final ImageView T3C1R1 = (ImageView) findViewById(R.id.T3C1R1);
btnPrevious = (Button) findViewById(R.id.btnPrevious2);
btnNext = (Button) findViewById(R.id.btnNext2);
txtTest = (TextView) findViewById(R.id.txtTest2);
// get the Intent that started this Activity
Intent in = getIntent();
// get the Bundle that stores the data of this Activity
Bundle b = in.getExtras();
// getting data from bundle
conditions = b.getIntArray("condition");
days = b.getStringArray("day");
// show data to layout
txtTest.setText("[Condition: " + conditions[0] + ", " + conditions[1] + ", " + conditions[2] + ", " + conditions[3] + "]");
/* for (int dc = 0; dc < conditions.length; dc++) {
dayWeatherCondtion(dc, days[dc]); // 0 --- Today
weatherConditionDress(dc, conditions[dc]); // 0 10
}*/
btnPrevious.setOnClickListener(new OnClickListener() {
@Override
public void onClick(View v) {
// TODO Auto-generated method stub
}
});
btnNext.setOnClickListener(new OnClickListener() {
@Override
public void onClick(View v) {
Bundle b = new Bundle();
b.putInt("condition", conditions[1]);
b.putString("day", days[1]);
// Creating Intent object
Intent in = new Intent(SecondActivity.this, DetailActivity.class);
// Storing bundle object into intent
in.putExtras(b);
startActivity(in);
}
});
}
/*private void weatherConditionDress(int day, int condition) { // 0 ---- 10
switch(condition){
case 2:
{
//String dress_array[] = ;
weatherDress(day, getResources().getStringArray(R.array.five)); //0 -----
break;
}
case 5:
case 6:
{
// String dress_array[] = getResources().getStringArray(R.array.five);
weatherDress(day, getResources().getStringArray(R.array.five));
break;
}
case 9:
{
// String dress_array[] = getResources().getStringArray(R.array.five);
weatherDress(day, getResources().getStringArray(R.array.nine));
break;
}
case 11:
{
//weatherCondtion(day, getResources().getStringArray(R.string.condition_11));
//String dress_array[] = getResources().getStringArray(R.array.five);
//weatherDress(getResources().getStringArray(R.array.five));
break;
}
case 12:
{
//String dress_array[] = getResources().getStringArray(R.array.five);
weatherDress(day, getResources().getStringArray(R.array.five));
break;
}
case 25:
{
// String dress_array[] = getResources().getStringArray(R.array.five);
weatherDress(day, getResources().getStringArray(R.array.twentyFive));
break;
}
case 26:
case 27:
case 28:
case 29:
case 30:
case 31:
{
// String dress_array[] = getResources().getStringArray(R.array.five);
weatherDress(day, getResources().getStringArray(R.array.twentySix));
break;
}
case 36:
{
// String dress_array[] = getResources().getStringArray(R.array.five);
weatherDress(day, getResources().getStringArray(R.array.thirtySix));
break;
}
case 37:
case 38:
case 39:
case 44:
{
// String dress_array[] = getResources().getStringArray(R.array.five);
weatherDress(day, getResources().getStringArray(R.array.thirtySeven));
break;
}
}
}
private void dayWeatherCondtion(int index, String day) {
dayCell[index].setImageDrawable(getDrawableByName(this,day));
Log.d("DAY","Day is " + day);
}
private void weatherDress(int day, String[] dress_array) {
for(int d = 0; d < dress_array.length; d++ ){
//ImageView temp = dressImageView[d];
Log.d("Dress Image", " "+ dressImageView[day][d]);
dressImageView[day][d].setImageDrawable(getDrawableByName(this, dress_array[d]));
}
}
//
public Drawable getDrawableByName(Context context, String name){
Resources resources = context.getResources();
final int resourceId = resources.getIdentifier(name, "drawable",
context.getPackageName());
return resources.getDrawable(resourceId);
}
*/
}