基本上我正在尝试更换“？”按任何键盘按钮。例如，如果问题显示为“0 + 1 =？”，我想要“1”来替换问号。
我的Java代码是：
package org.example.question;
import java.util.Random;
import android.app.Activity;
import android.os.Bundle;
import android.util.Log;
import android.view.View;
import android.widget.Button;
import android.widget.TextView;
public class QuestionActivity extends Activity implements View.OnClickListener {
/** Called when the activity is first created. */
//variable for different questions
int fnum0, snum0,fnum1, snum1,fnum2, snum2,fnum3, snum3,
fnum4, snum4,fnum5, snum5,fnum6, snum6,fnum7, snum7,
fnum8, snum8,fnum9, snum9, answer;
//variable and type declaration for buttons and text
Button keyOne;
Button keyTwo;
Button keyThree;
Button keyFour;
Button keyFive;
Button keySix;
Button keySeven;
Button keyEight;
Button keyNine;
Button keyDel;
Button keyZero;
Button keyHash;
Button keySubtract;
TextView display;
TextView display1;
TextView answer0;
int question=0;
boolean q;
@Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.main);
//display text on screen
display1 = (TextView)findViewById(R.id.Guess);
display = (TextView)findViewById(R.id.Title);
answer0 = (TextView)findViewById(R.id.Answer);
///Code for correct and incorrect
//assigning names to each keypad
keyOne= (Button) findViewById(R.id.keypad_1);
keyTwo= (Button) findViewById(R.id.keypad_2);
keyThree= (Button) findViewById(R.id.keypad_3);
keyFour= (Button) findViewById(R.id.keypad_4);
keyFive = (Button) findViewById(R.id.keypad_5);
keySix= (Button) findViewById(R.id.keypad_6);
keySeven = (Button) findViewById(R.id.keypad_7);
keyEight = (Button) findViewById(R.id.keypad_8);
keyNine = (Button) findViewById(R.id.keypad_9);
keyZero = (Button) findViewById(R.id.keypad_0);
keySubtract = (Button) findViewById(R.id.keypad_subtract);
keyHash = (Button) findViewById(R.id.keypad_hash);
keyDel = (Button) findViewById(R.id.delete);
//setting button to produce an event when each button is pressed
keyOne.setOnClickListener(this); keyTwo.setOnClickListener(this); keyThree.setOnClickListener(this);
keyFour.setOnClickListener(this); keyFive.setOnClickListener(this); keySix.setOnClickListener(this);
keySeven.setOnClickListener(this); keyEight.setOnClickListener(this); keyNine.setOnClickListener(this);
keySubtract.setOnClickListener(this); keyHash.setOnClickListener(this); keyDel.setOnClickListener(this);
}
public void onClick(View arg0) {
switch(arg0.getId()){
case R.id.keypad_hash:
//Generates random numbers
fnum0 = (int) ((double) ((Math.random() * 10)));
snum0 = (int) ((double) ((Math.random() * 10)));
String str = "";
//genrates random number between 0 to 9
int operation = (int) ((double) ((Math.random() * 10)));
Log.d("debug", "operation value: " + operation);
if(operation == 0)
str = fnum0+ "+" + snum0+ "="+ "??";
else if(operation == 1)
str = fnum0 + "-" + snum0+ "="+ "??";
else if(operation == 2)
str = fnum0 + "*" + snum0+ "="+ "??" ;
else
str = fnum0 + "/" + snum0+ "="+ "??";
display.setText(str);
break;
case R.id.keypad_1:
if(q="?" )
{
display.setText("1");
}
else
{
return;
}
break;
case R.id.keypad_2:
display.setText("2");
break;
case R.id.keypad_3:
display.setText("3");
break;
case R.id.keypad_4:
display.setText("4");
break;
case R.id.keypad_5:
display.setText("5");
break;
case R.id.keypad_6:
display.setText("6");
break;
case R.id.keypad_7:
display.setText("7");
break;
case R.id.keypad_8:
display.setText("8");
break;
case R.id.keypad_9:
display.setText("9");
break;
case R.id.delete:
display.setText("");
break;
case R.id.keypad_0:
display.setText("0");
break;
case R.id.keypad_subtract:
display.setText("-");
break;
}
}
public void requestFocus() {
// TODO Auto-generated method stub
}
}
然而，此时它显示的问题是“0 + 1 =”但是当我按下它时它会移除问题并在屏幕上自行显示“1”。
更新错误
case R.id.keypad_1:
public void onClick(View arg0) {
String str=null;
switch(arg0.getId()){
case R.id.keypad_hash:
//Generates random numbers
fnum0 = (int) ((double) ((Math.random() * 10)));
snum0 = (int) ((double) ((Math.random() * 10)));
//genrates random number between 0 to 9
int operation = (int) ((double) ((Math.random() * 10)));
Log.d("debug", "operation value: " + operation);
if(operation == 0)
str = fnum0+ "+" + snum0+ "="+ "??";
else if(operation == 1)
str = fnum0 + "-" + snum0+ "="+ "??";
else if(operation == 2)
str = fnum0 + "*" + snum0+ "="+ "??" ;
else
str = fnum0 + "/" + snum0+ "="+ "??";
display.setText(str);
break;
case R.id.keypad_1:
if(str.equals("??"))
{
String str1 = display.getText().toString();
display.setText(str1.replace("??", "1"));
}
else
{
return;
}
break;
应用程序正在崩溃.....
答案 0 :(得分：1)
而不是
display.setText("1");
写
display.setText(str.replace("??", "1"));
替换方法表示替换“??” str字符串上带有“1”文本的文本，因此搜索“??”文本并将其替换为此字符串上的“1”文本。
比较字符串应使用equals方法，例如代替str==?，写：
str.equals("?");
替换keys_1案例的代码（删除if）：
case R.id.keypad_1:
String str1 = display.getText().toString();
display.setText(str1.replace("??", "1"));
break;
希望它有所帮助。
答案 1 :(得分：0)
我不确定所需的确切方法调用（已经有一段时间了），但您要做的是从显示中获取当前文本，修改它并重新显示它。我相信这会奏效：
String str = display.getText().toString();
display.setText(str.replace("??", "1"));