这个简单的计算器应用程序有一个奇怪的问题。 添加/减去/乘法和除法工作，但是： 1.当数字乘以十进制值（一切都是双打）时，我的结果乘以10。 例如：7 * 7给我49.0 2.当乘以数字时，我有时得到一个近乎好的结果（只乘以10，但是后面跟着很多零，最后是1） 示例：1.1 * 1.1 = 12.100000000000001
package org.example.paweljezierski.calculator;
import android.os.Bundle;
import android.support.v7.app.AppCompatActivity;
import android.support.v7.widget.Toolbar;
import android.view.Menu;
import android.view.MenuItem;
import android.view.View;
import android.widget.Button;
import android.widget.TextView;
public class MainActivity extends AppCompatActivity {
//I'm declaring every button so I'm able to use it
//I could probably do it in one line, but it's cleaner this way
Button buttonplus;
Button buttonminus;
Button buttonmultiply;
Button buttonpower;
Button buttondivide;
Button buttonequals;
Button buttondot;
Button buttonclear;
Button button1;
Button button2;
Button button3;
Button button4;
Button button5;
Button button6;
Button button7;
Button button8;
Button button9;
Button button0;
//I'm declaring every TextView
TextView textresult;
TextView textinput;
//value1, value2 are two values that we'll do math on
double value1 = 0, value2 = 0, result = 0;
//mathoperation will be set to [1;4] by operation button to know what math to do later
int mathoperation = 0;
//for holding information
String a, a2, aa, n;
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
Toolbar toolbar = (Toolbar) findViewById(R.id.toolbar);
setSupportActionBar(toolbar);
// Initialize both text fields
textresult = (TextView)findViewById(R.id.textresult);
textinput = (TextView)findViewById(R.id.textinput);
//I initialize every button
buttonplus =(Button)findViewById(R.id.buttonplus);
buttonminus =(Button)findViewById(R.id.buttonminus);
buttonmultiply =(Button)findViewById(R.id.buttonmultiply);
buttondivide =(Button)findViewById(R.id.buttondivide);
buttonpower =(Button)findViewById(R.id.buttonpower);
buttondivide =(Button)findViewById(R.id.buttondivide);
buttonequals =(Button)findViewById(R.id.buttonequals);
buttondot =(Button)findViewById(R.id.buttondot);
buttonclear=(Button) findViewById(R.id.buttonclear);
button1 =(Button)findViewById(R.id.button1);
button2 =(Button)findViewById(R.id.button2);
button3 =(Button)findViewById(R.id.button3);
button4 =(Button)findViewById(R.id.button4);
button5 =(Button)findViewById(R.id.button5);
button6 =(Button)findViewById(R.id.button6);
button7 =(Button)findViewById(R.id.button7);
button8 =(Button)findViewById(R.id.button8);
button9 =(Button)findViewById(R.id.button9);
button0 =(Button)findViewById(R.id.button0);
button1.setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View v) {
a=textinput.getText().toString();
a=a+"1";
a2=a2+"1";
textinput.setText(a);
}
});
button2.setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View v) {
a=textinput.getText().toString();
a=a+"2";
a2=a2+"2";
textinput.setText(a);
}
});
button3.setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View v) {
a=textinput.getText().toString();
a=a+"3";
a2=a2+"3";
textinput.setText(a);
}
});
button4.setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View v) {
a=textinput.getText().toString();
a=a+"4";
a2=a2+"4";
textinput.setText(a);
}
});
button5.setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View v) {
a=textinput.getText().toString();
a=a+"5";
a2=a2+"5";
textinput.setText(a);
}
});
button6.setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View v) {
a=textinput.getText().toString();
a=a+"6";
a2=a2+"6";
textinput.setText(a);
}
});
button7.setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View v) {
a=textinput.getText().toString();
a=a+"7";
a2=a2+"7";
textinput.setText(a);
}
});
button8.setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View v) {
a=textinput.getText().toString();
a=a+"8";
a2=a2+"8";
textinput.setText(a);
}
});
button9.setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View v) {
a=textinput.getText().toString();
a=a+"9";
a2=a2+"9";
textinput.setText(a);
}
});
button0.setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View v) {
a=textinput.getText().toString();
a=a+"0";
a2=a2+"0";
textinput.setText(a);
}
});
buttondot.setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View v) {
a=textinput.getText().toString();
a=a+".";
textinput.setText(a);
}
});
buttonplus.setOnClickListener(new View.OnClickListener()
{
public void onClick(View v) {
if (mathoperation == 0)
{
aa=a;
mathoperation=1;
a=a+" + ";
textinput.setText(a);
a2 = "0";
}
}
});
buttonminus.setOnClickListener(new View.OnClickListener()
{
public void onClick(View v) {
if (mathoperation == 0)
{
aa=a;
mathoperation=2;
a=a+" - ";
textinput.setText(a);
a2 = "0";
}
}
});
buttonmultiply.setOnClickListener(new View.OnClickListener()
{
public void onClick(View v) {
if (mathoperation == 0)
{
aa=a;
mathoperation=3;
a=a+" * ";
textinput.setText(a);
a2 = "0";
}
}
});
buttondivide.setOnClickListener(new View.OnClickListener() {
public void onClick(View v) {
if (mathoperation == 0) {
aa = a;
mathoperation = 4;
a=a+" / ";
textinput.setText(a);
a2 = "0";
}
}
});
buttonclear.setOnClickListener(new View.OnClickListener()
{
public void onClick(View v) {
aa = "";
a = "0";
mathoperation = 0;
result = 0;
textinput.setText("");
textresult.setText("");
}
});
buttonequals.setOnClickListener(new View.OnClickListener()
{
public void onClick(View v) {
if(mathoperation==1){
value1=Double.parseDouble(aa);
value2=Double.parseDouble(a2);
result = value1 + value2;
}
else
if(mathoperation==2){
value1=Double.parseDouble(aa);
value2=Double.parseDouble(a2);
result = value1 - value2;
}else
if(mathoperation==3){
value1=Double.parseDouble(aa);
value2=Double.parseDouble(a2);
result = value1 * value2;
}
else
if(mathoperation==4){
value1=Double.parseDouble(aa);
value2=Double.parseDouble(a2);
result = value1 / value2;
}
n = Double.toString(result);
textresult.setText(n);
aa = "";
a = "0";
mathoperation = 0;
result = 0;
}
});
// FloatingActionButton fab = (FloatingActionButton) findViewById(R.id.fab);
// fab.setOnClickListener(new View.OnClickListener() {
// @Override
// public void onClick(View view) {
// Snackbar.make(view, "Replace with your own action", Snackbar.LENGTH_LONG)
// .setAction("Action", null).show();
// }
// });
}
@Override
public boolean onCreateOptionsMenu(Menu menu) {
// Inflate the menu; this adds items to the action bar if it is present.
getMenuInflater().inflate(R.menu.menu_main, menu);
return true;
}
@Override
public boolean onOptionsItemSelected(MenuItem item) {
// Handle action bar item clicks here. The action bar will
// automatically handle clicks on the Home/Up button, so long
// as you specify a parent activity in AndroidManifest.xml.
int id = item.getItemId();
//noinspection SimplifiableIfStatement
if (id == R.id.action_settings) {
return true;
}
return super.onOptionsItemSelected(item);
}
}
编辑：如果在它们之后没有任何值与零不同，我想隐藏零。 假设我计算7 * 0.7并且仅显示6个值。 它会给我4.900000 我想要隐藏五个零。 怎么做？
答案 0 :(得分：0)
以下是您的工作：
Set-Location当您点击buttondot时，您还需要执行a2 = a2 +＆＃34;。＆＃34;
换句话说：
click Button1
a=1
a2=1
click Button.
a=1.
// add "a2=1."
click Button1
a=1.1
a2=11 <---
click ButtonMultiply
operation=3
aa=1.1
a=1.1*
a2=0
click Button1
a=1.1*1
a2=1
click Button.
a=1.1*1.
// add "a2=1."
click Button1
a=1.1*1.1
a2=11 <-----
click Buttonresult
value1 = 1.1
value2 = 11
// value2 = 1.1
result = 12.10000000000000000000001
// result = 1.210000000000000001
用于格式化之后：Round a double to 2 decimal places
PS：欢迎使用Stackoverflow !!