support
i'm beginner in android programmation on android-studio and when i run my app i've got : "Error java.LangNullPointerExeption attempt to invoke virtual method 'java.lang.String java.lang.Object.toString()' on a null object reference.

Please i spend my time to search what is this error, i'm blocked in my first project, i need your help to continue.

Thanks you so much, Waks!

i join my code:

package com.my.newproject;

import android.app.*;
import android.os.*;
import android.view.*;
import android.view.View.*;
import android.widget.*;
import android.content.*;
import android.graphics.*;
import android.media.*;
import android.net.*;
import android.text.*;
import android.util.*;
import android.webkit.*;
import android.animation.*;
import android.view.animation.*;
import java.util.*;
import java.text.*;
import android.support.v7.app.AppCompatActivity;
import android.widget.LinearLayout;
import android.widget.Button;
import java.util.Timer;
import java.util.TimerTask;
import android.content.Intent;
import android.net.Uri;
import android.animation.ObjectAnimator;
import android.view.animation.LinearInterpolator;
import android.view.animation.AccelerateInterpolator;
import android.view.animation.DecelerateInterpolator;
import android.view.animation.AccelerateDecelerateInterpolator;
import android.view.animation.BounceInterpolator;
import android.view.View;

public class MainActivity extends AppCompatActivity {

private Timer _timer = new Timer();

private double rotation = 0;
private double click = 0;
private double xbk = 0;

private LinearLayout linear1;
private LinearLayout linear2;
private Button menu;
private LinearLayout linear3;
private LinearLayout linear4;
private Button button8;
private Button button2;
private Button button3;
private Button button4;
private Button button5;
private Button button6;

private TimerTask timer;
private Intent intent = new Intent();
private ObjectAnimator ani = new ObjectAnimator();
private Intent show = new Intent();
@Override
protected void onCreate(Bundle _savedInstanceState) {
super.onCreate(_savedInstanceState);
setContentView(R.layout.main);
initialize(_savedInstanceState);
initializeLogic();
}

private void initialize(Bundle _savedInstanceState) {

linear1 = (LinearLayout) findViewById(R.id.linear1);
linear2 = (LinearLayout) findViewById(R.id.linear2);
menu = (Button) findViewById(R.id.menu);
linear3 = (LinearLayout) findViewById(R.id.linear3);
linear4 = (LinearLayout) findViewById(R.id.linear4);
button8 = (Button) findViewById(R.id.button8);
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);

menu.setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View _view) {
click++;
if (click == 1) {
ani.setTarget(linear4);
ani.setPropertyName("translationX");
ani.setFloatValues((float)(SketchwareUtil.getDip(getApplicationContext(), (int)(-200)) - SketchwareUtil.getDisplayWidthPixels(getApplicationContext())), (float)(0 - SketchwareUtil.getDisplayWidthPixels(getApplicationContext())));
ani.setDuration((int)(500));
ani.setRepeatMode(ValueAnimator.REVERSE);
ani.setRepeatCount((int)(0));
ani.setInterpolator(new AccelerateInterpolator());
ani.start();
}
else {
if (click == 2) {
ani.setTarget(linear4);
ani.setFloatValues((float)(0 - SketchwareUtil.getDisplayWidthPixels(getApplicationContext())), (float)(SketchwareUtil.getDip(getApplicationContext(), (int)(-200)) - SketchwareUtil.getDisplayWidthPixels(getApplicationContext())));
ani.start();
click = 0;
}
}
}
});

button8.setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View _view) {

}
});

button2.setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View _view) {
intent.setClass(getApplicationContext(), DonneesActivity.class);
startActivity(intent);
}
});

button3.setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View _view) {
intent.setClass(getApplicationContext(), ClientsActivity.class);
startActivity(intent);
}
});

button4.setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View _view) {
intent.setClass(getApplicationContext(), ProduitsActivity.class);
startActivity(intent);
}
});

button5.setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View _view) {
intent.setClass(getApplicationContext(), EditionfactdevActivity.class);
startActivity(intent);
}
});

button6.setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View _view) {
intent.setClass(getApplicationContext(), VisuelfactdevActivity.class);
startActivity(intent);
}
});
}
private void initializeLogic() {
click = 0;
}

@Override
protected void onActivityResult(int _requestCode, int _resultCode, Intent _data) {
super.onActivityResult(_requestCode, _resultCode, _data);

switch (_requestCode) {

default:
break;
}
}

@Override
public void onBackPressed() {
xbk++;
if (xbk == 2) {
xbk = 2;
finish();
}
else {
SketchwareUtil.showMessage(getApplicationContext(), "Presser 2 fois pour quitter !");
}
}
@Deprecated
public void showMessage(String _s) {
Toast.makeText(getApplicationContext(), _s, Toast.LENGTH_SHORT).show();
}

@Deprecated
public int getLocationX(View _v) {
int _location[] = new int[2];
_v.getLocationInWindow(_location);
return _location[0];
}

@Deprecated
public int getLocationY(View _v) {
int _location[] = new int[2];
_v.getLocationInWindow(_location);
return _location[1];
}

@Deprecated
public int getRandom(int _min, int _max) {
Random random = new Random();
return random.nextInt(_max - _min + 1) + _min;
}

@Deprecated
public ArrayList<Double> getCheckedItemPositionsToArray(ListView _list) {
ArrayList<Double> _result = new ArrayList<Double>();
SparseBooleanArray _arr = _list.getCheckedItemPositions();
for (int _iIdx = 0; _iIdx < _arr.size(); _iIdx++) {
if (_arr.valueAt(_iIdx))
_result.add((double)_arr.keyAt(_iIdx));
}
return _result;
}

@Deprecated
public float getDip(int _input){
return TypedValue.applyDimension(TypedValue.COMPLEX_UNIT_DIP, _input, getResources().getDisplayMetrics());
}

@Deprecated
public int getDisplayWidthPixels(){
return getResources().getDisplayMetrics().widthPixels;
}

@Deprecated
public int getDisplayHeightPixels(){
return getResources().getDisplayMetrics().heightPixels;
}

}