Java Android setText方法不支持'；t在文本视图中设置文本
我正试图编写一个简单的android应用程序来熟悉sdk，但我不明白为什么setText方法不改变TextView。基本上，我希望用户输入一个字符串，让用户选择在字符串上运行哪个方法，并将输出设置为Textview，但我似乎无法设置Textview。我曾尝试在onCreate、cases之后的开关中以及在每种情况下调用该方法，但没有人将文本设置为输出值。有人知道我做错了什么吗Java Android setText方法不支持'；t在文本视图中设置文本,java,android,Java,Android,我正试图编写一个简单的android应用程序来熟悉sdk，但我不明白为什么setText方法不改变TextView。基本上，我希望用户输入一个字符串，让用户选择在字符串上运行哪个方法，并将输出设置为Textview，但我似乎无法设置Textview。我曾尝试在onCreate、cases之后的开关中以及在每种情况下调用该方法，但没有人将文本设置为输出值。有人知道我做错了什么吗 package com.example.firstapp; import android.app.Activity;
package com.example.firstapp;
import android.app.Activity;
import android.os.Bundle;
import android.view.View;
import android.view.View.OnClickListener;
import android.widget.Button;
import android.widget.EditText;
import android.widget.TextView;
public class TextChange extends Activity implements OnClickListener{
Button findUpperCase, everyOther, vowelReplace, vowelCount;
EditText input;
TextView output;
String inputText, outputText;
@Override
protected void onCreate(Bundle savedInstanceState) {
// TODO Auto-generated method stub
super.onCreate(savedInstanceState);
setContentView(R.layout.textchanger);
initializeVar();
output.setText(outputText);
}
public void initializeVar(){
findUpperCase = (Button) findViewById(R.id.finduppercase);
everyOther = (Button) findViewById(R.id.everyother);
vowelReplace = (Button) findViewById(R.id.vreplace);
vowelCount = (Button) findViewById(R.id.vcount);
input = (EditText) findViewById(R.id.stringinput);
output = (TextView) findViewById(R.id.output);
}
public static String findUpperCase(String x){
//Initialize output value
String output = "";
//For loop to loop through each character of the string
for (int i = 0; i <= x.length()-1; i++)
{
//Convert letter to char value and compare it to the ASCII values for capital letters
if (Character.isUpperCase(x.charAt(i)))
{
//Add each capital letter to the output string
output += x.substring(i, i+1) + " ";
}
}
//If not uppercase letters tell user
if (output.equals("")){
output = "No upper case characters";
}
//Return the capital letters or message to user and exit method
return output;
}
//Method used to get every other letter
public static String everyOther(String x){
//Set initial value of output
String output = "";
//Use for loop to get every other character by incrementing i by 2 each time
for(int i=0; i<=x.length() - 1; i+=2){
//Set letter equal to a temperary holder
char temp = x.charAt(i);
//If it is the first letter add to output without a space preceeding it
if (i == 0){
//New output is set as the old output plus the temp value without a space
output = output + temp;
}
//If it is not the first letter do this
else{
//New output is set as the old output plus the temp value with a space
output = output + " " + temp;
}
}
//Return the output
return output;
}
//Method to replace the vowel with "_"
public static String vowelReplace(String x){
//Search each string for vowels and ignore the case, when found replace with a "_"
String output = x.replaceAll("(?i)[aeiou]","_");
//Return the output
return output;
}
//Method to count the vowels
public static int vowelCount(String x){
//Set a counter
int count = 0;
//Set an array of char characters containing all the letters
char vowels[] = {'a','e','i','o','u','A','E','I','O','U'};
//For loop to check each letter for vowels
for (int i = 0; i <= x.length() - 1; i++){
//For loop to check each character against values in vowels array
for(int z = 0; z <= 9; z++){
//If a vowel is found increment the count
if (x.charAt(i) == vowels[z]){
//Increment the count
count++;
}
}
}
//Return the number of vowels
return count;
}
//Method to identify the vowel positions
public static String vowelPositions(String x){
//Initialize an output variable
String output = "";
//Set a temp string variable
String values = "";
//Set an array of char characters containing all the letters
char vowels[] = {'a','e','i','o','u','A','E','I','O','U'};
//For loop to check each letter for vowels
for(int z = 0; z < x.length(); z++){
//For loop to check each character against values in vowels array
for (int i = 0; i <= 9; i++){
//Check if each character is equal to any value in the array value
if (x.charAt(z) == vowels[i]){
//If it is the first vowel found do not add a space before adding to output
if(output.equals("")){
//Set first value of output
output = "[" + z + "]";
}
else{
//Add each position of the vowels to the output string
values = " [" + z + "]";
//Set new value of outputs to old value plus the value of values
output = output + values;
}
}
}
}
//Return the location of the vowels
return "Vowels are located at the following indexes:" + output;
}
@Override
public void onClick(View v) {
// TODO Auto-generated method stub
inputText = input.getText().toString();
switch(v.getId()){
case R.id.finduppercase:
outputText = findUpperCase(inputText);
break;
case R.id.everyother:
outputText = everyOther(inputText);
break;
case R.id.vcount:
outputText=Integer.toString(vowelCount(inputText));
break;
case R.id.vpos:
outputText = vowelPositions(inputText);
break;
case R.id.vreplace:
outputText = vowelReplace(inputText);
break;
}
}
}
package com.example.firstapp；
导入android.app.Activity；
导入android.os.Bundle；
导入android.view.view；
导入android.view.view.OnClickListener；
导入android.widget.Button；
导入android.widget.EditText；
导入android.widget.TextView；
公共类TextChange扩展活动实现OnClickListener{
按钮FindPerCase、everyOther、元音替换、元音计数；
编辑文本输入；
文本视图输出；
字符串inputText，outputText；
@凌驾
创建时受保护的void（Bundle savedInstanceState）{
//TODO自动生成的方法存根
super.onCreate（savedInstanceState）；
setContentView（R.layout.textchanger）；
initializeVar（）；
output.setText（outputText）；
}
public void initializeVar（）{
findUpperCase=（按钮）findviewbyd（R.id.findUpperCase）；
everyOther=（按钮）findViewById（R.id.everyOther）；
元音替换=（按钮）findViewById（R.id.vreplace）；
元音计数=（按钮）findViewById（R.id.vcount）；
输入=（EditText）findViewById（R.id.stringinput）；
输出=（TextView）findViewById（R.id.output）；
}
公共静态字符串findUpperCase（字符串x）{
//初始化输出值
字符串输出=”；
//For循环遍历字符串的每个字符
对于（int i=0；i
有人知道我做错了什么吗
package com.example.firstapp;
import android.app.Activity;
import android.os.Bundle;
import android.view.View;
import android.view.View.OnClickListener;
import android.widget.Button;
import android.widget.EditText;
import android.widget.TextView;
public class TextChange extends Activity implements OnClickListener{
Button findUpperCase, everyOther, vowelReplace, vowelCount;
EditText input;
TextView output;
String inputText, outputText;
@Override
protected void onCreate(Bundle savedInstanceState) {
// TODO Auto-generated method stub
super.onCreate(savedInstanceState);
setContentView(R.layout.textchanger);
initializeVar();
output.setText(outputText);
}
public void initializeVar(){
findUpperCase = (Button) findViewById(R.id.finduppercase);
everyOther = (Button) findViewById(R.id.everyother);
vowelReplace = (Button) findViewById(R.id.vreplace);
vowelCount = (Button) findViewById(R.id.vcount);
input = (EditText) findViewById(R.id.stringinput);
output = (TextView) findViewById(R.id.output);
}
public static String findUpperCase(String x){
//Initialize output value
String output = "";
//For loop to loop through each character of the string
for (int i = 0; i <= x.length()-1; i++)
{
//Convert letter to char value and compare it to the ASCII values for capital letters
if (Character.isUpperCase(x.charAt(i)))
{
//Add each capital letter to the output string
output += x.substring(i, i+1) + " ";
}
}
//If not uppercase letters tell user
if (output.equals("")){
output = "No upper case characters";
}
//Return the capital letters or message to user and exit method
return output;
}
//Method used to get every other letter
public static String everyOther(String x){
//Set initial value of output
String output = "";
//Use for loop to get every other character by incrementing i by 2 each time
for(int i=0; i<=x.length() - 1; i+=2){
//Set letter equal to a temperary holder
char temp = x.charAt(i);
//If it is the first letter add to output without a space preceeding it
if (i == 0){
//New output is set as the old output plus the temp value without a space
output = output + temp;
}
//If it is not the first letter do this
else{
//New output is set as the old output plus the temp value with a space
output = output + " " + temp;
}
}
//Return the output
return output;
}
//Method to replace the vowel with "_"
public static String vowelReplace(String x){
//Search each string for vowels and ignore the case, when found replace with a "_"
String output = x.replaceAll("(?i)[aeiou]","_");
//Return the output
return output;
}
//Method to count the vowels
public static int vowelCount(String x){
//Set a counter
int count = 0;
//Set an array of char characters containing all the letters
char vowels[] = {'a','e','i','o','u','A','E','I','O','U'};
//For loop to check each letter for vowels
for (int i = 0; i <= x.length() - 1; i++){
//For loop to check each character against values in vowels array
for(int z = 0; z <= 9; z++){
//If a vowel is found increment the count
if (x.charAt(i) == vowels[z]){
//Increment the count
count++;
}
}
}
//Return the number of vowels
return count;
}
//Method to identify the vowel positions
public static String vowelPositions(String x){
//Initialize an output variable
String output = "";
//Set a temp string variable
String values = "";
//Set an array of char characters containing all the letters
char vowels[] = {'a','e','i','o','u','A','E','I','O','U'};
//For loop to check each letter for vowels
for(int z = 0; z < x.length(); z++){
//For loop to check each character against values in vowels array
for (int i = 0; i <= 9; i++){
//Check if each character is equal to any value in the array value
if (x.charAt(z) == vowels[i]){
//If it is the first vowel found do not add a space before adding to output
if(output.equals("")){
//Set first value of output
output = "[" + z + "]";
}
else{
//Add each position of the vowels to the output string
values = " [" + z + "]";
//Set new value of outputs to old value plus the value of values
output = output + values;
}
}
}
}
//Return the location of the vowels
return "Vowels are located at the following indexes:" + output;
}
@Override
public void onClick(View v) {
// TODO Auto-generated method stub
inputText = input.getText().toString();
switch(v.getId()){
case R.id.finduppercase:
outputText = findUpperCase(inputText);
break;
case R.id.everyother:
outputText = everyOther(inputText);
break;
case R.id.vcount:
outputText=Integer.toString(vowelCount(inputText));
break;
case R.id.vpos:
outputText = vowelPositions(inputText);
break;
case R.id.vreplace:
outputText = vowelReplace(inputText);
break;
}
}
}
在onCreate（）
中，您正在TextView
上调用setText（）
，但您传递的参数是null
，因为您尚未初始化输出
代码中没有其他地方可以调用setText（）
首先，在Onclick
方法中没有调用setText
，其次，没有将侦听器设置为按钮
1） 将onClickListners设置为您的按钮
public void initializeVar(){
findUpperCase = (Button) findViewById(R.id.finduppercase);
everyOther = (Button) findViewById(R.id.everyother);
vowelReplace = (Button) findViewById(R.id.vreplace);
vowelCount = (Button) findViewById(R.id.vcount);
findUpperCase.setOnClickListener(this);
everyOther.setOnClickListener(this);
vowelReplace.setOnClickListener(this);
vowelCount.setOnClickListener(this);
}
2） 在onClick方法中的setText：
@Override
public void onClick(View v) {
// TODO Auto-generated method stub
inputText = input.getText().toString();
switch(v.getId()){
case R.id.finduppercase:
outputText = findUpperCase(inputText);
output.setText(outputText);
break;
case R.id.everyother:
outputText = everyOther(inputText);
output.setText(outputText);
break;
case R.id.vcount:
outputText=Integer.toString(vowelCount(inputText));
output.setText(outputText);
break;
case R.id.vpos:
outputText = vowelPositions(inputText);
output.setText(outputText);
break;
case R.id.vreplace:
outputText = vowelReplace(inputText);
output.setText(outputText);
break;
}
}
您是否检查了TextView是否实际可见？如果您在TextView上调用getText，是否能够打印回文本？在onClick中调用setText据我所知，您只能在onCreate（）
中调用setText（）
一次。